test-drb

test-drb@ccmp.vtda.org

101090 discussions

Some IBM Core Memory Artifact Help if possible

by thomas.gardner＠sbcglobal.net

Hi Can anyone provide: 1) The dimensions of the memory plane from the Type 738 Memory used in the IBM 704 and other computers of its generation. There is an undimensioned photo in Pugh's "Memories That Shaped An Industry" C 1984 (p.158) that makes a 4 KiB plane look to be about 14 in by 7 in. A high quality photo would be appreciated. I can send anyone a scan if they care. 2) A photo and dimensions of the M4I memory plane (that's M4eye not M4one) that was used in the System 360 M65 and M70. The Computer History Museum has an artifact identified as a, Magnetic Core Plane, IBM /360 Model 65, http://www.computerhistory.org/collections/accession/102627815, but it looks too small and too crude to be for those machines. I could be wrong so I would appreciate someone who could verify the artifact or alternatively the correct photo and dimensions. Pugh is unclear but he does imply a much larger frame. This is for a web exhibit I am preparing for the Computer History Museum Any help would be appreciated. Thanks Tom

15 years, 6 months

Wanted : Monitor Capable of TTL RGB

by williams.dan＠gmail.com

Hi, I am on the lookout for a monitor something similar to a Phillips cm3388 does anyone near London have one they would like to sell or trade, or know of anywhere I could get one. Thanks Dan

15 years, 6 months

Repairing core memories....

by jdr_use＠bluewin.ch

So I have these 2 PDP-8/L core stacks I am trying to recover: One would be perfect, if bit 3 @ adr 0 would be alive... Although this is 99.99% OK, it is of course not good enough. The other stack seems to be a total loss : 2 sense wires are open circuit, more than 20 select diodes shorted. Of course the further quality of the cores is unknown. Is there any realistic way of getting one fully functional stack out of these ? Removing a single core from the really bad stack to the almost OK stack would seems almost feasible to me, since address 0 is bound to be on a edge of a core mat. Any ideas / suggestions ? Jos

15 years, 6 months

classiccmp web site mirrors?

by tingox＠gmail.com

Hello, As I still can't reach the classiccmp web site - are there mirrors anywhere? (I have the same problem with bitsavers.org, luckily most mirrors works) HAND -- Regards, Torfinn Ingolfsen

15 years, 6 months

68K (was: Happy Birthday VAX 11/780)

by bqt＠softjar.se

On 2010-10-30 01:12, Ethan Dicks<ethan.dicks at gmail.com> wrote: > On Fri, Oct 29, 2010 at 2:26 PM, Brent Hilpert<hilpert at cs.ubc.ca> wrote: >> > On 2010 Oct 29, at 10:39 AM, Ethan Dicks wrote: >>> >> >>> >> That all depends. ?Back in the day, what we did was not demand-paged >>> >> virtual memory (something supported natively on the VAX and the 68010 >>> >> (but not effectively on the 68000)... (which is part of what >>> >> distinguishes the 68010 from the 68000 - instruction restart). >> > >> > There have been a couple of indications it was the '10 that added the >> > instruction restart, but was the implementation in the '10 bug-free? > I know it works well enough in early Sun workstations and the AT&T > Unix PC (3B1/7300), but I have no knowledge of any required > workarounds due to possible bugs. Yes, the 68010 worked fine with demand paging. The 68000 did not. Neither of them implemented instructions restarts, though. As noted below, the 68010 did instuction suspension instead. The "interesting" workarounds that I've hear of are actually 68000-related. As the 68000 could not do instruction restarts, people originally through you couldn't use it in demand paging systems. However, I think it was Apollo (but it might have been some other company) did come up with a solution. The 68000 could not restart an instruction, nor suspend them and later resume. However, you could stall the processor indefinitely. Using their own designed MMU (there were none from Motorola for the 68000), and a second CPU, Apollo made the primary CPU stall on a page fault, and the secondady CPU wake up. The secondary CPU could then do a page in. Once the page was available, the primary CPU was allowed to continue. (One alternative version of the design that I heard was that the secondary CPU would run in parallel with the primary, but slightly behind, so that it could be interrupted before starting to execute the instruction causing a page fault, and then you'd have the saved state before the page fault in the secondary CPU, but I don't think that this is a plausible design). >> > I didn't deal with the problem directly, heard about it from some friends >> > who were programming around it, and it would have been 1989, so long after >> > the 00->10 transition. My recollection about the issue was there was a bug >> > under certain conditions that was fixed in the next version, as distinct >> > from a 'new feature', but perhaps it was just the way the problem was >> > described to me or the way I understood what was being said. > I have no memory of issues with instruction restart on the '10, but I > didn't use that feature of the chip when I was doing embedded product > development 20+ years ago (we only used it for the "loop mode" > 1-instruction cache feature that allowed so-called "DBcc loops" to run > ~50% faster due to not needing fetch cycles while in the loop). > > Could what you remember be something to do with "instruction restart" > vs "instruction continuation"? (a distinction I was not making, but > now that I've read this - > http://www.easy68k.com/paulrsm/doc/dpbm68k1.htm - perhaps that's a > better way to describe it). They are two different things, yes. But they serve the same purpose. It's just different ways of dealing with what to do after a page fault (or any trap from which you want to recover). The advantage of instruction continuation, especially with the 68010, is that it didn't introduce any incompatibilities with the 68000. If you had implemented instruction restarts instead, you would have had to introduce a bunch of new registers in the CPU that kept track of partial modifications done before the trap, so that you could undo them before restarting the instruction. With instruction continuation, it's all preserved internally in the CPU without exposing the software to anything new. Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol

15 years, 6 months

manual for M9312 bootstrap module

by jack.rubin＠ameritech.net

Can anyone provide an electronic copy (or link) to the DEC publication, EK-M9312-TM-002 M9312 Bootstrap-Terminator Module Technical Manual? The previous link at http://www.computer.museum.uq.edu.au/unfinished/ no longer seems to work. Thanks, Jack

15 years, 6 months

VCFMW Pics and Shirts

by silent700＠gmail.com

It's been a week since VCFMW and now we've got some galleries to display! You can find them at vcfmw.org. I have video from the abortive uStream broadcast that I still need to chop up (it made a 2.8gb .flv file!) but will post as soon as I can. I'm not at all happy with the video or audio quality, so different methods will be employed next year. We still have a stock of shirts remaining. The design can be seen here: http://picasaweb.google.com/Silent700/VCFMW50OfficialGraphics#5512512730455… If anyone would like one, they are $15 incl. shipping in the US (talk to me if you're international.) Here are the sizes we have left (you can tell which we'll order more and less of next year :) Same yellow design on black or Navy-Blue Gildan pre-shrunk cotton shirts: Blue M: 2 Black M: 1 Black L: 11 Black XXL: 8 Blue XXL: 3 Blue XXXL: 2 Thanks and see you next year! -j

15 years, 6 months

cctalk Digest, Vol 86, Issue 71

by dm561＠torfree.net

Date: Sun, 31 Oct 2010 12:47:06 -0500 From: "MikeS" <dm561 at torfree.net> Subject: Re: cctalk Digest, Vol 86, Issue 68 ----------------- Sorry about that (sending the digest); no idea how that got sent, will make sure it doesn't happen again. Humbly apologetic, mike

15 years, 6 months

Memory mapped I/O

by bqt＠softjar.se

On 2010-10-30 23:18, Brent Hilpert<hilpert at cs.ubc.ca> wrote: > On 2010 Oct 30, at 12:34 PM, Dave McGuire wrote: > >> > On 10/30/10 1:08 PM, Chuck Guzis wrote: >>> >> Aside from expanding program storage, the large addressing space was >>> >> used to map file space (another type of "memory-mapped I/O"), so file >>> >> access was actually performed through the paging hardware/software. >>> >> That was kind of cool, as the STAR was a memory-to-memory vector >>> >> machine, so you could use vector instructions on entire files, rather >>> >> than have to issue reads and writes for pieces of a file. >> > >> > That functionality is in use all over the place today as mmap(), >> > accessing files as if they were memory, pushing the read/write burden >> > out into the VM system. It's extremely effective. > I remember in the 80's (programming primarily on BSD (and VMS)) > thinking it would nice to have that functionality, how easy it would > make a lot of file-access programming, and that it would be easy to add > on a VM system. Of course, I was in ignorance of the prior histories > such as the STAR that Chuck mentions. A few years later a friend would > tell me about the new mmap function in unix. This might very well be totally wrong, but I remember hearing about it at the time, that Sun (who I believe was the ones to first implement mmap()) bascially took the whole TOPS-20 concept and translated it to Unix. A bit surprised no TOPS-20 hackers have spoken up yet... This was around for a long time on the PDP-10 before this. Not sure how it correlates timewise to CDC and the STAR though. But no matter if Unix took it from TOPS-20 or not, there is no denying that TOPS-20 had this a long time before it came to Unix. >> > I'd not consider it to be "memory-mapped I/O" at all, though, in the >> > context of "a processor reading and writing I/O ports". Sure, file >> > I/O is a sort of I/O, and mmap() and similar techniques map that file >> > I/O into the address space, but the context of this discussion...and >> > indeed, most, it not all use of the term "memory-mapped I/O" doesn't >> > refer to this sort of thing. > Well, Chuck did say "a type of". If files are a form of abstracted disk > I/O, then mmap is a form of abstracted memory-mapped I/O. Memory mapped files are kindof neat, but it's not I/O at all in one way. After all, all you do is just leave the actual I/O to the virtual memory system instead of doing it yourself. So it's not that the I/O is done in any different way, it's just initiated by someone else. Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol

15 years, 6 months

Repairing core memories....

by gerhard.kreuzer＠liftoff.at

Hi, Please let me know any outcome of this project, I also have some stacks, 8/L and 8/e of unknown condition and would be some day in the situation to start repair. Thanks a lot, and much success!! With best regards Gerhard -----Urspr?ngliche Nachricht----- Von: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org] Im Auftrag von cctalk-request at classiccmp.org Gesendet: Sonntag, 31. Oktober 2010 19:37 An: cctalk at classiccmp.org Betreff: cctalk Digest, Vol 86, Issue 71 Send cctalk mailing list submissions to cctalk at classiccmp.org To subscribe or unsubscribe via the World Wide Web, visit http://www.classiccmp.org/mailman/listinfo/cctalk or, via email, send a message with subject or body 'help' to cctalk-request at classiccmp.org You can reach the person managing the list at cctalk-owner at classiccmp.org When replying, please edit your Subject line so it is more specific than "Re: Contents of cctalk digest..." Today's Topics: 1. Re: Need to find parts 82S23 / 74S188 (Chuck Guzis) 2. Re: [OT]? Sun Ultra 60 (Zane H. Healy) 3. Re: Large geometry MFM drive testing (Chuck Guzis) 4. Re: [OT]? Sun Ultra 60 (Dave McGuire) 5. Re: [OT]? Sun Ultra 60 (Zane H. Healy) 6. Re: [OT]? Sun Ultra 60 (Alexandre Souza - Listas) 7. Re: [OT]? Sun Ultra 60 (Alexandre Souza - Listas) 8. Re: Need to find parts 82S23 / 74S188 (Alexandre Souza - Listas) 9. Re: CDC STAR was: Happy Birthday VAX 11/780 (influence of) (Chuck Guzis) 10. Re: Need to find parts 82S23 / 74S188 (Eric Smith) 11. Re: cctalk Digest, Vol 86, Issue 68 (MikeS) 12. Re: Virtual memory (Johnny Billquist) 13. Re: Memory mapped I/O (Johnny Billquist) 14. Re: Repairing core memories.... (O. Sharp) ---------------------------------------------------------------------- Message: 1 Date: Sun, 31 Oct 2010 10:11:39 -0700 From: "Chuck Guzis" <cclist at sydex.com> Subject: Re: Need to find parts 82S23 / 74S188 To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Message-ID: <4CCD40DB.19611.F4760 at cclist.sydex.com> Content-Type: text/plain; charset=ISO-8859-1 On 31 Oct 2010 at 8:28, Glen Slick wrote: > On Sat, Oct 30, 2010 at 2:40 PM, Chuck Guzis <cclist at sydex.com> wrote: > > > The bigger problem for me would be finding a programmer for these > > things. ?I've got a mess of SN74S471s and no way to program them. > > > I have the Nat Semi DM74LS471 on the device list of my programmer, but > not the SN74S471. Any chance the programming algorithms are the same? They probably are. Somewhere in the history of TI part numbers, they changed some of the bipolar memories from the SN74xxx part number to TBPxxx. I can't recall which way my parts are labeled, but they're 471s under the hood. --Chuck ------------------------------ Message: 2 Date: Sun, 31 Oct 2010 10:12:31 -0700 From: "Zane H. Healy" <healyzh at aracnet.com> Subject: Re: [OT]? Sun Ultra 60 To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>, General Discussion: Message-ID: <p06240808c8f34f3401a1(a)[192.168.1.157]> Content-Type: text/plain; charset="us-ascii" ; format="flowed" At 12:06 PM -0400 10/31/10, Dave McGuire wrote: >On 10/31/10 6:35 AM, Alexandre Souza - Listas wrote: >>Hmmm, is an Ultra 60 offtopic? :o) > > WAY off-topic. Some of us would debate that. I personally think the Ultra 2 and the Ultra 60 as two of Sun's greatest machines. They're practical to own, and take processors that will make them fairly useful. I'm also pretty fond of Sparc 20's. My Ultra 60 has dual 450Mhz CPU's, it's far more practical than my SunBlade 1000 (to much electricity used, and heat generated). My only problem is I've never gotten a Copper GigE card. >>Just got one (eee!!!), > > Cool! Agreed! >>now what to do with that? > > Just about anything you can think of, except lots of floating point math. One comment, the older the OS the better, and OpenBSD is an option. >>I could use a keyboard and mouse from Sun, since I have none :( > > Problem solved; I'll put a set in the box I'm packing up for you. Cool! In the mean time plug in a serial terminal. The Ultra 60 is one of the few Suns I've ever used a keyboard and mouse on, though I typically used a PS/2 keyboard an mouse on mine. I have a Sun adapter that allows that, and it works with a KVM. I've not gotten any of my Sun HW set back up since we bought our house. Sun HW and a couple SGI O2's are the only real exceptions to my rule about not collecting UNIX HW. I used the Suns a lot as general purpose workstations and servers at home. Either running Solaris, or OpenBSD. Zane -- | Zane H. Healy | UNIX Systems Administrator | | healyzh at aracnet.com | OpenVMS Enthusiast | | | Photographer | +----------------------------------+----------------------------+ | My flickr Photostream | | http://www.flickr.com/photos/33848088 at N03/ | ------------------------------ Message: 3 Date: Sun, 31 Oct 2010 10:15:01 -0700 From: "Chuck Guzis" <cclist at sydex.com> Subject: Re: Large geometry MFM drive testing To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Message-ID: <4CCD41A5.8728.125D5A at cclist.sydex.com> Content-Type: text/plain; charset=US-ASCII On 30 Oct 2010 at 15:06, Steven Hirsch wrote: > All, > > I'm trying to evaluate a pile of large MFM hard drives for > functionality. I'm attaching them to a WD-1006V-MM2 controller and > running Sprinrite 4 under DOS 6.0 (using a 486 EISA motherboard). > > This works fine for drives with < 1024 cylinders, but I cannot seem to > remember (or figure out) how to surface-test drives with more > cylinders (e.g. Priam V185 with 1166). The convention when the cylinder field overflows 10 bits is to use the two high-order bits of the head field (that's why MFM, and for that matter, IDE drives max out at 64 heads when non-LBA geometry is used.). --Chuck ------------------------------ Message: 4 Date: Sun, 31 Oct 2010 13:19:35 -0400 From: Dave McGuire <mcguire at neurotica.com> Subject: Re: [OT]? Sun Ultra 60 To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> Message-ID: <4CCDA527.1050903 at neurotica.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed On 10/31/10 1:12 PM, Zane H. Healy wrote: >>> Hmmm, is an Ultra 60 offtopic? :o) >> >> WAY off-topic. > > Some of us would debate that. I personally think the Ultra 2 and the > Ultra 60 as two of Sun's greatest machines. They're practical to own, > and take processors that will make them fairly useful. I agree that they're two of their best designs. I just think that machines which are still pretty common in production environments, built around a modern architecture, are hardly "classic computers". That's all. > I'm also pretty fond of Sparc 20's. As am I. >>> now what to do with that? >> >> Just about anything you can think of, except lots of floating point math. > > One comment, the older the OS the better, and OpenBSD is an option. ...unless you want to use it for real work of course. (referencing "older", not OpenBSD) -Dave -- Dave McGuire Port Charlotte, FL ------------------------------ Message: 5 Date: Sun, 31 Oct 2010 10:24:16 -0700 From: "Zane H. Healy" <healyzh at aracnet.com> Subject: Re: [OT]? Sun Ultra 60 To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>, General Discussion: Message-ID: <p0624080bc8f35668b1fd(a)[192.168.1.157]> Content-Type: text/plain; charset="us-ascii" ; format="flowed" At 1:19 PM -0400 10/31/10, Dave McGuire wrote: >>One comment, the older the OS the better, and OpenBSD is an option. > > ...unless you want to use it for real work of course. >(referencing "older", not OpenBSD) We have a production system still running Solaris 2.6 at work. I was thinking along the lines of the older the OS, the less cruft, and the better on the older hardware. For the past few years I've typically run Solaris 8 at home, though I have Solaris 10 on the SunBlade 1000. Zane -- | Zane H. Healy | UNIX Systems Administrator | | healyzh at aracnet.com | OpenVMS Enthusiast | | | Photographer | +----------------------------------+----------------------------+ | My flickr Photostream | | http://www.flickr.com/photos/33848088 at N03/ | ------------------------------ Message: 6 Date: Sun, 31 Oct 2010 15:32:37 -0200 From: "Alexandre Souza - Listas" <pu1bzz.listas at gmail.com> Subject: Re: [OT]? Sun Ultra 60 To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Message-ID: <053701cb7924$22bebc20$6600a8c0 at portajara> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response >> Hmmm, is an Ultra 60 offtopic? :o) > WAY off-topic. Sorry you all :o( >> now what to do with that? > Just about anything you can think of, except lots of floating point > math. I always wanted to run solaris, now I have a chance :oD Internet navigation in a BIG computer :oD >> I could use a keyboard and mouse from Sun, since I have none :( > Problem solved; I'll put a set in the box I'm packing up for you. W00T! :oD Thanks a lot, Dave! :oD Since it is SO offtopic, I'll direct my other questions directly to you ------------------------------ Message: 7 Date: Sun, 31 Oct 2010 15:34:28 -0200 From: "Alexandre Souza - Listas" <pu1bzz.listas at gmail.com> Subject: Re: [OT]? Sun Ultra 60 To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Message-ID: <053801cb7924$2451b830$6600a8c0 at portajara> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response > Sun HW and a couple SGI O2's are the only real exceptions to my rule about > not collecting UNIX HW. I used the Suns a lot as general purpose > workstations and servers at home. Either running Solaris, or OpenBSD. My impossible dream is to get a SGI machine. Any of them. There is an Ozone (or something like) in a surplus seller I know, but he asks just too much money for it. Someday I'll get one :oD It is a pride and joy for me to have a SGI machine on my desk :oD ------------------------------ Message: 8 Date: Sun, 31 Oct 2010 15:37:08 -0200 From: "Alexandre Souza - Listas" <pu1bzz.listas at gmail.com> Subject: Re: Need to find parts 82S23 / 74S188 To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Message-ID: <053901cb7924$25794840$6600a8c0 at portajara> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original >I have the Nat Semi DM74LS471 on the device list of my programmer, but >not the SN74S471. Any chance the programming algorithms are the same? AFAIK the algorithm is the same, the only difference is in speed/fan out ------------------------------ Message: 9 Date: Sun, 31 Oct 2010 10:54:08 -0700 From: "Chuck Guzis" <cclist at sydex.com> Subject: Re: CDC STAR was: Happy Birthday VAX 11/780 (influence of) To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Message-ID: <4CCD4AD0.28674.362B3F at cclist.sydex.com> Content-Type: text/plain; charset=US-ASCII On 31 Oct 2010 at 8:21, Jerome H. Fine wrote: > Interesting!! I worked for CDC in Toronto from around 1972 to 1977 on > the local PL-50 program. IIRC, the PL-50 was a much slower version of > the STAR-100, but with the same instruction set. Initially, the goal > was to write an operating system. I was part of the Sunnyvale mafia and worked with quite a number of your Canadian co-workers. Anil and I later partnered up on the FORTRAN compiler for the ETA-10. You probably remember that the PL- 50/STAR-65 met an unfortunate fate at the hands of the corporate "leave nothing behind" people. I witnessed firsthand, the destruction of the two STAR-1B systems a couple of years later. It wasn't pretty--a dumpster, bolt cutters and large hammers. I saved a heatsink from the power supply--there wasn't much else left intact. I begged to be allowed to take the ROS stack from one system, but no such luck. The stations were removed and sent back to Arden Hills. -- I'm going from memory on this one, but there's some STAR literature on bitsavers if you want to check my facts. 256 registers of 64 bits; if halfword mode was selected, the lower 128 were doubled and the upper 128 were inaccessible. Many registers had special meanings, including program status, cycle timer and a few others. Internally, memory was fetched 512 bits ("Super word" or "sword"; really 544 bits with ECC included) and the vector pipes were 128 bits wide (2 single-precision results per cycle). An odd machine in that scalar operations were most decidedly RISC in attitude. For example, there were only load and store register- memory operations and one had to use 2 instructions (EX and ELEN) to enter a full 64-bit immediate constant into a register. No stack or auto-increment/decremet per se; subroutine linkage was done with a sort of S/360-style LM-STM combo "swap" instruction that simultaneously stored and loaded any number of registers. The machine architecture itself was basically 3-address, so instructions were either 32 bits or 64 bits in length. Before an ECO ("Rev. R") was installed on all systems, all registers could also be addressed as the lower 256 words of user memory address space. This hugely complicated instruction scheduling and so it was determined that it wasn't needed. I know you guys used the RED OS, but we had to use STAR-OS from LLL as our base in Sunnyvale. It was basically a message-passing OS with a controller started by the job scheduler, which could have as many controllees as desired. You could send a message up the chain, one level, or to the top or broadcast to all controllees. I recall that the termination message content was the characters "ALL DONE". Regarding paging, I saw my share of DEADBEEF codes (was the STAR OS the first to use this failure code?). At some point we went from a demand-paging algorithm to a working-set one, but the stuff that the pager had to keep track of made the code a nightmare. Jim Smith suffered a lot on that thing. It didn't help that we had to scavenge time on the customer systems at LLL or hop the "noon balloon" out of San Jose to use the system at ADL. One thing that I never got to try on the 100 was seeing how long a maximum-length packed BCD divide would take. Given that the byte instruction field lengths were 16 bits, it meant either 65K or 131K digits... One memory I have is being sent to Arden Hills in January during the OPEC oil embargo and settling in for the night in the machine room at ADL because it was warmer than my room at the Ramada. I"d love to find someone who spent time on the TI ASC to compare notes... --Chuck ------------------------------ Message: 10 Date: Sun, 31 Oct 2010 11:07:43 -0700 From: Eric Smith <eric at brouhaha.com> Subject: Re: Need to find parts 82S23 / 74S188 To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> Message-ID: <4CCDB06F.9090905 at brouhaha.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed On 10/31/2010 10:11 AM, Chuck Guzis wrote: > On 31 Oct 2010 at 8:28, Glen Slick wrote: > > >> On Sat, Oct 30, 2010 at 2:40 PM, Chuck Guzis<cclist at sydex.com> wrote: >> >>>> The bigger problem for me would be finding a programmer for these >>>> >>> things. I've got a mess of SN74S471s and no way to program them.> >>> >> I have the Nat Semi DM74LS471 on the device list of my programmer, but >> not the SN74S471. Any chance the programming algorithms are the same? >> > They probably are. Somewhere in the history of TI part numbers, they > changed some of the bipolar memories from the SN74xxx part number to > TBPxxx. I can't recall which way my parts are labeled, but they're > 471s under the hood. > True, but it has absolutely *nothing* to do with whether a National Semiconductor DM74LS471 uses the same programming algorithm and electrical parameters as the SN74S471. They might, but it was not uncommon for different vendors to have parts that did NOT program in the same way. They often did their own designs, with different types of fuses and materials, requiring different programming parameters. Eric ------------------------------ Message: 11 Date: Sun, 31 Oct 2010 12:47:06 -0500 From: "MikeS" <dm561 at torfree.net> Subject: Re: cctalk Digest, Vol 86, Issue 68 To: <cctalk at classiccmp.org> Message-ID: <8021827792C6419AB1C1B7613E954423 at vl420mt> Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original ----- Original Message ----- From: <cctalk-request at classiccmp.org> To: <cctalk at classiccmp.org> Sent: Saturday, October 30, 2010 4:18 PM Subject: cctalk Digest, Vol 86, Issue 68 > Send cctalk mailing list submissions to > cctalk at classiccmp.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://www.classiccmp.org/mailman/listinfo/cctalk > or, via email, send a message with subject or body 'help' to > cctalk-request at classiccmp.org > > You can reach the person managing the list at > cctalk-owner at classiccmp.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of cctalk digest..." > > > Today's Topics: > > 1. Re: Happy Birthday VAX 11/780 (influence of) (Chuck Guzis) > 2. Re: TTL HEX LED driver chip (Chuck Guzis) > 3. Re: TRS-80 Model II Manuals (Fred Jan Kraan) > 4. Re: DiscFerret: First working hardware, firmware and > microcode! (Philip Pemberton) > 5. Re: TRS-80 Model II Manuals (Tony Duell) > 6. Re: TRS-80 Model II Manuals (Chuck Guzis) > 7. Re: DiscFerret: First working hardware, firmware and > microcode! (Dave McGuire) > 8. Re: Happy Birthday VAX 11/780 (influence of) (Dave McGuire) > 9. Re: DiscFerret: First working hardware, firmware and > microcode! (Philip Pemberton) > 10. Re: TTL HEX LED driver chip (Brent Hilpert) > 11. Re: Happy Birthday VAX 11/780 (influence of) (Brent Hilpert) > 12. Fall cleaning, some small machines for free (Bob Rosenbloom) > 13. Re: DiscFerret: First working hardware, firmware and > microcode! (Chuck Guzis) > 14. Need to find parts 82S23 / 74S188 (alan canning) > 15. Re: Happy Birthday VAX 11/780 (influence of) (Chuck Guzis) > 16. Re: DiscFerret: First working hardware, firmware and > microcode! (Philip Pemberton) > 17. Re: TTL HEX LED driver chip (Tony Duell) > 18. Re: Nuclear Data ND 6600 (Tony Duell) > 19. Re: TRS-80 Model II Manuals (Tony Duell) > 20. Re: TTL HEX LED driver chip (Tony Duell) > 21. Re: TTL HEX LED driver chip (Tony Duell) > 22. Re: Wanted : Monitor Capable of TTL RGB (Tony Duell) > 23. Re: I/O models (was RE: Happy Birthday VAX 11/780 (influence > of)) (Tony Duell) > 24. Re: Fall cleaning, some small machines for free (Brent Hilpert) > 25. Re: Need to find parts 82S23 / 74S188 (ben) > 26. Re: TRS-80 Model II Manuals (Geoffrey Reed) > 27. Re: Need to find parts 82S23 / 74S188 (Tony Duell) > 28. Re: Need to find parts 82S23 / 74S188 (Chuck Guzis) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sat, 30 Oct 2010 10:08:19 -0700 > From: "Chuck Guzis" <cclist at sydex.com> > Subject: Re: Happy Birthday VAX 11/780 (influence of) > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Message-ID: <4CCBEE93.7369.1A49AC at cclist.sydex.com> > Content-Type: text/plain; charset=US-ASCII > > On 29 Oct 2010 at 21:14, Johnny Billquist wrote: > >> If your program vrites data to address 0, and reads it back, and get >> the same data back, and another program on the same machine, at >> roughly the same time, write to address 0, and reads the same data >> back, and that data is different than the first programs data, then >> I'd say you have virtual memory. > > So, your definition ties virtual memory into multi-user access? > That's not the way I learned it. > > Consider (again folks, I'm sorry for the reference) the CDC 6600 > (circa 1964). Every user is given a relocation address (called RA) > and field length (FL) as a way of partitioning main memory. Each > user's memory addressing space is kept isolated from every other's > and this fits your definiton because one user's location X was > different from every other user's location X and there was no way for > a user to tell what his RA was; i.e. each user was safely "boxed in". > > That's not virtual memory by any stretch of the definition. Over- > committing memory meant writing/reading the entire FL of a user to > disk ("rollout" and "rollin"). > > Now consider the STAR-100 (I think it would qualify as the first > virtual memory machine of CDC), circa 1969. Every user got an > addressing space of 48 bits, but the machine itself had only > 512Kwords (64 bit) of physical storage. For production use, most of > the time the system was run in single-user mode (kept thrashing down > with large data sets). That fits my definition of VM because the > user was fooled into thinking that there was more physical memory > than there really was. > > Aside from expanding program storage, the large addressing space was > used to map file space (another type of "memory-mapped I/O"), so file > access was actually performed through the paging hardware/software. > That was kind of cool, as the STAR was a memory-to-memory vector > machine, so you could use vector instructions on entire files, rather > than have to issue reads and writes for pieces of a file. > > So I think we differ considerably in our definitions. > > --Chuck > > > > ------------------------------ > > Message: 2 > Date: Sat, 30 Oct 2010 10:21:07 -0700 > From: "Chuck Guzis" <cclist at sydex.com> > Subject: Re: TTL HEX LED driver chip > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Message-ID: <4CCBF193.19364.2603DF at cclist.sydex.com> > Content-Type: text/plain; charset=US-ASCII > > On the same topic here, can anyone interpret the "state table" on the > second page of the National DM74LS447 7-segment decoder datasheet? > > http://pdf1.alldatasheet.com/datasheet- > pdf/view/149198/NSC/DM74LS447N.html > > I tend to think of state diagrams as belonging to things such as > counters and don't have a clue as to what to make of the one > furnished. > > --Chuck > > > > > > ------------------------------ > > Message: 3 > Date: Sat, 30 Oct 2010 20:05:06 +0200 > From: Fred Jan Kraan <fjkraan at xs4all.nl> > Subject: Re: TRS-80 Model II Manuals > To: cctech at classiccmp.org > Message-ID: <4CCC5E52.9000802 at xs4all.nl> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Thanks to the ever-useful JP Hindin, I've obtained a set of TRS-DOS >> disks and other application disks for my TRS-80 Model II system, which >> is the entire setup pictured here, plus a bit more: >> >> http://oldcomputers.net/pics/TRS-80-II_table.JPG >> >> It's been sitting, covered, pretty much since I obtained it, but now I >> can try reviving it and actually seeing what it can do. I'm going to >> tear into it and clean the drives and so forth, document what it has, >> etc. and then boot 'er up and see what we can see. >> >> I'm looking for a copy of the Technical Ref manual for it; despite >> finding scans of the covers and so forth online, I'm unable to actually >> locate one. In addition to that, if someone has a Shugart 8" Service >> Manual, that might come in damned handy for making sure those are up to >> speed as well. >> > See > http://electrickery.xs4all.nl/comp/mirror/trs-80_archives/Manuals/Hardware/M odel_II_Technical_Reference_Manual_(1980)(Radio_Shack)(pdf).zip. > The Shugart stuff should be included. > > Essential this is from a modified copy of the files that were available > from http://www.trs-80.com/ (copied without permission). >> Many thanks, >> >> Nathan >> >> > Success, > > Fred Jan > > P.S. My own adventures with the Model II: > http://www.xs4all.nl/~fjkraan/comp/trs80m2/ > > > > ------------------------------ > > Message: 4 > Date: Sat, 30 Oct 2010 19:35:32 +0100 > From: Philip Pemberton <classiccmp at philpem.me.uk> > Subject: Re: DiscFerret: First working hardware, firmware and > microcode! > To: General Discussion: On-Topic and Off-Topic Posts > <cctalk at classiccmp.org> > Message-ID: <4CCC6574.8010103 at philpem.me.uk> > Content-Type: text/plain; charset=UTF-8; format=flowed > > On 30/10/10 17:26, Al Kossow wrote: >> If it's going to be an adapter, could you add holes for SA1000-style 8" >> drives (50pin/20pin cabling)? > > I almost mistook that for a floppy drive until I looked it up on > Bitsavers...! > > I can't see any real reason why SA1000 support couldn't be added to the > bridge-board. Looks like the only changes required would be: > - An oscillator to generate the 3.6866us +/- 0.1% timing clock > (270982 to 271524Hz, nominal 271253Hz). Although I have no idea what > standard crystal frequencies could be used to generate that signal. The > FPGA's PLL might be persuaded to do it, though, I'll have to check. > - Two jumpers to disconnect the Timing Clock from the ST412/506 Data > connector when these are not in use (or maybe just a second connector?) > - A 50-pin connector for the SA1000 control cable > > The extra cost probably isn't worth worrying about... though I might > have to restrict drive selection to Drive 0 only in order to get enough > I/O pins for head selection. > > Thanks, > -- > Phil. > classiccmp at philpem.me.uk > http://www.philpem.me.uk/ > > > ------------------------------ > > Message: 5 > Date: Sat, 30 Oct 2010 19:47:54 +0100 (BST) > From: ard at p850ug1.demon.co.uk (Tony Duell) > Subject: Re: TRS-80 Model II Manuals > To: cctalk at classiccmp.org > Message-ID: <m1PCGTE-000J3xC at p850ug1> > Content-Type: text/plain > >> locate one. In addition to that, if someone has a Shugart 8" Service >> Manual, that might come in damned handy for making sure those are up to >> speed as well. > > ...And if they;'re not, it's most likelyto be the drive belt. Yes I know > 'up to speed' wasn't meant to be taken literally, but that seemed too > good to miss :-) > > More seriously, what model of Shugart8" drive? Are there not manuals for > them on bitsavers? > > -tony > > > ------------------------------ > > Message: 6 > Date: Sat, 30 Oct 2010 11:55:03 -0700 > From: "Chuck Guzis" <cclist at sydex.com> > Subject: Re: TRS-80 Model II Manuals > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Message-ID: <4CCC0797.19723.7C011E at cclist.sydex.com> > Content-Type: text/plain; charset=US-ASCII > > On 30 Oct 2010 at 19:47, Tony Duell wrote: > >> ...And if they;'re not, it's most likelyto be the drive belt. Yes I >> know 'up to speed' wasn't meant to be taken literally, but that seemed >> too good to miss :-) > > Well, he could have a 220V 50Hz model and be running it on 120V 60Hz > (the motor will develop sufficient torque to spin the disk). I've > made that mistake once. The results from the reverse would be > "interesting"... > > --Chuck > > > > ------------------------------ > > Message: 7 > Date: Sat, 30 Oct 2010 15:29:06 -0400 > From: Dave McGuire <mcguire at neurotica.com> > Subject: Re: DiscFerret: First working hardware, firmware and > microcode! > To: General Discussion: On-Topic and Off-Topic Posts > <cctalk at classiccmp.org> > Message-ID: <4CCC7202.6050705 at neurotica.com> > Content-Type: text/plain; charset=UTF-8; format=flowed > > On 10/30/10 2:35 PM, Philip Pemberton wrote: >> I can't see any real reason why SA1000 support couldn't be added to the >> bridge-board. Looks like the only changes required would be: >> - An oscillator to generate the 3.6866us +/- 0.1% timing clock (270982 >> to 271524Hz, nominal 271253Hz). Although I have no idea what standard >> crystal frequencies could be used to generate that signal. The FPGA's >> PLL might be persuaded to do it, though, I'll have to check. > > You could stick a little AD9833 (or similar) DDS chip on there. It's > overkill, but they're pretty cheap now, and you'll get the desired > frequency spot-on. > > -Dave > > -- > Dave McGuire > Port Charlotte, FL > > > ------------------------------ > > Message: 8 > Date: Sat, 30 Oct 2010 15:34:25 -0400 > From: Dave McGuire <mcguire at neurotica.com> > Subject: Re: Happy Birthday VAX 11/780 (influence of) > To: General Discussion: On-Topic and Off-Topic Posts > <cctalk at classiccmp.org> > Message-ID: <4CCC7341.1090704 at neurotica.com> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 10/30/10 1:08 PM, Chuck Guzis wrote: >> Aside from expanding program storage, the large addressing space was >> used to map file space (another type of "memory-mapped I/O"), so file >> access was actually performed through the paging hardware/software. >> That was kind of cool, as the STAR was a memory-to-memory vector >> machine, so you could use vector instructions on entire files, rather >> than have to issue reads and writes for pieces of a file. > > That functionality is in use all over the place today as mmap(), > accessing files as if they were memory, pushing the read/write burden > out into the VM system. It's extremely effective. > > I'd not consider it to be "memory-mapped I/O" at all, though, in the > context of "a processor reading and writing I/O ports". Sure, file I/O > is a sort of I/O, and mmap() and similar techniques map that file I/O > into the address space, but the context of this discussion...and indeed, > most, it not all use of the term "memory-mapped I/O" doesn't refer to > this sort of thing. > > -Dave > > -- > Dave McGuire > Port Charlotte, FL > > > ------------------------------ > > Message: 9 > Date: Sat, 30 Oct 2010 20:58:46 +0100 > From: Philip Pemberton <classiccmp at philpem.me.uk> > Subject: Re: DiscFerret: First working hardware, firmware and > microcode! > To: General Discussion: On-Topic and Off-Topic Posts > <cctalk at classiccmp.org> > Message-ID: <4CCC78F6.9040004 at philpem.me.uk> > Content-Type: text/plain; charset=UTF-8; format=flowed > > On 30/10/10 20:29, Dave McGuire wrote: >> You could stick a little AD9833 (or similar) DDS chip on there. It's >> overkill, but they're pretty cheap now, and you'll get the desired >> frequency spot-on. > > ?8.25 each with no quantity discount is *not* cheap. The FPGA only costs > a few quid more than that. > > Digikey have them for ?5.86, but that's still more than a crystal. I > wonder how the host adapters for the SA1000s generated this clock > frequency... it does seem somewhat odd. > > The other thing is, I'd be concerned about releasing hardware with > SA1000 support without testing it on an actual drive. I'm willing to bet > the chances of me finding a working SA1000 in 230V/50Hz configuration > are somewhere between 'slim' and 'nil'. > > I'll guarantee ST506 support though, given that I've got an ST277R RLL > drive and controller here. Just need an MFM controller for it, or the > RLL code tables for the Seagate ST21R or ST22R controller (which IIRC > uses an Adaptec AIC010 chip)... > > -- > Phil. > classiccmp at philpem.me.uk > http://www.philpem.me.uk/ > > > ------------------------------ > > Message: 10 > Date: Sat, 30 Oct 2010 13:23:00 -0700 > From: Brent Hilpert <hilpert at cs.ubc.ca> > Subject: Re: TTL HEX LED driver chip > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Message-ID: <8534ab06c8e0281a7fcfc54d6a70efa5 at cs.ubc.ca> > Content-Type: text/plain; charset=US-ASCII; format=flowed > > On 2010 Oct 30, at 10:21 AM, Chuck Guzis wrote: > >> On the same topic here, can anyone interpret the "state table" on the >> second page of the National DM74LS447 7-segment decoder datasheet? >> >> http://pdf1.alldatasheet.com/datasheet- >> pdf/view/149198/NSC/DM74LS447N.html >> >> I tend to think of state diagrams as belonging to things such as >> counters and don't have a clue as to what to make of the one >> furnished. > > It's obviously a state diagram for a decade counter, my guess is > someone just screwed up making the datasheet and included the state > diagram from some other device. > > > > ------------------------------ > > Message: 11 > Date: Sat, 30 Oct 2010 13:36:50 -0700 > From: Brent Hilpert <hilpert at cs.ubc.ca> > Subject: Re: Happy Birthday VAX 11/780 (influence of) > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Message-ID: <d40186fd9ded72a101d654d9516da0f5 at cs.ubc.ca> > Content-Type: text/plain; charset=US-ASCII; format=flowed > > On 2010 Oct 30, at 12:34 PM, Dave McGuire wrote: > >> On 10/30/10 1:08 PM, Chuck Guzis wrote: >>> Aside from expanding program storage, the large addressing space was >>> used to map file space (another type of "memory-mapped I/O"), so file >>> access was actually performed through the paging hardware/software. >>> That was kind of cool, as the STAR was a memory-to-memory vector >>> machine, so you could use vector instructions on entire files, rather >>> than have to issue reads and writes for pieces of a file. >> >> That functionality is in use all over the place today as mmap(), >> accessing files as if they were memory, pushing the read/write burden >> out into the VM system. It's extremely effective. > > I remember in the 80's (programming primarily on BSD (and VMS)) > thinking it would nice to have that functionality, how easy it would > make a lot of file-access programming, and that it would be easy to add > on a VM system. Of course, I was in ignorance of the prior histories > such as the STAR that Chuck mentions. A few years later a friend would > tell me about the new mmap function in unix. > > >> I'd not consider it to be "memory-mapped I/O" at all, though, in the >> context of "a processor reading and writing I/O ports". Sure, file >> I/O is a sort of I/O, and mmap() and similar techniques map that file >> I/O into the address space, but the context of this discussion...and >> indeed, most, it not all use of the term "memory-mapped I/O" doesn't >> refer to this sort of thing. > > Well, Chuck did say "a type of". If files are a form of abstracted disk > I/O, then mmap is a form of abstracted memory-mapped I/O. > > > > ------------------------------ > > Message: 12 > Date: Sat, 30 Oct 2010 13:36:53 -0700 (PDT) > From: Bob Rosenbloom <bobalan at sbcglobal.net> > Subject: Fall cleaning, some small machines for free > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Message-ID: <960487.42595.qm at web80502.mail.mud.yahoo.com> > Content-Type: text/plain; charset=us-ascii > > > Fall cleaning! > > I have a bunch of old computers and some peripherals. Most are not tested > and I expect they may need some work to become operational, though some > may work correctly as-is. Anyway, I'm hoping to find people interested in > restoring these systems. > > There are three Burroughs B25 systems, each has a processor box, disk box, > monitor, keyboard, and power supply. There is one box of docs and > diskettes and one, very dirty, printer. > http://www.anifur.com/clist/misc-b1.jpg > http://www.anifur.com/clist/misc-b2.jpg > http://www.anifur.com/clist/misc-b3.jpg > http://www.anifur.com/clist/misc-b4.jpg > > IBM convertible, an early laptop type system. > > A Computer Products portable, thermal, serial terminal. > http://www.anifur.com/clist/misc-ptr.jpg > > A Radio Shack TRS-80 model I with expansion chassis and monitor. I believe > this has a bad power supply. > http://www.anifur.com/clist/misc-rs.jpg > > A NEC Spinwriter terminal. This is like a Diablo daisywheel terminal > except the print element is a cylinder. I know this one needs work but > does power up. > http://www.anifur.com/clist/misc-spin.jpg > > Some kind of cartridge tape system. I think it's SCSI interfaced. I don't > believe this has ever been used. > http://www.anifur.com/clist/misc-tape.jpg > > A large flatbed scanner that I also believe is unused. It's SCSI > interfaced. UMAX 3000. > http://www.anifur.com/clist/misc-scanner.jpg > > Digitech RS-232 analyzer with manuals. This runs CP/M 86 but I don't have > the boot disc for it. Does power up. > http://www.anifur.com/clist/misc-anal.jpg > > Kaypro 2, powers up and ask for a system disk. > http://www.anifur.com/clist/kaypro1.jpg > > Hitachi pen plotter. This has a parallel interface. It powers up and works > from the front panel. Light weight. > http://www.anifur.com/clist/hitachi1.jpg > > Panasonic NV-A960 VCR editing unit. > http://www.anifur.com/clist/a960-1.jpg > > Nicolet Zeta 8A pen plotter. 8 pens. Also powers up and works from the > front panel. Serial interface. > > All of these are located in the Santa Cruz, CA mountains, near the Bonny > Doon airport. I can possibly bring something into Santa Clara where I > work. Best to come visit and check them out here. I really don't want to > ship anything as I just don't have the time or energy. > > Please rescue these before I scrap them, I really need the space and these > are now outside, but covered under a Quonset hut. > > Bob > > > ------------------------------ > > Message: 13 > Date: Sat, 30 Oct 2010 13:39:13 -0700 > From: "Chuck Guzis" <cclist at sydex.com> > Subject: Re: DiscFerret: First working hardware, firmware and > microcode! > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Message-ID: <4CCC2001.27472.DB6112 at cclist.sydex.com> > Content-Type: text/plain; charset=US-ASCII > > On 30 Oct 2010 at 15:29, Dave McGuire wrote: > >> On 10/30/10 2:35 PM, Philip Pemberton wrote: >> > I can't see any real reason why SA1000 support couldn't be added to >> > the bridge-board. Looks like the only changes required would be: - >> > An oscillator to generate the 3.6866us +/- 0.1% timing clock (270982 >> > to 271524Hz, nominal 271253Hz). Although I have no idea what >> > standard crystal frequencies could be used to generate that signal. >> > The FPGA's PLL might be persuaded to do it, though, I'll have to >> > check. >> >> You could stick a little AD9833 (or similar) DDS chip on there. >> It's >> overkill, but they're pretty cheap now, and you'll get the desired >> frequency spot-on. > > Also, aren't the read/write data signals on the SA1000 differential? > Or do I have them confused with the ST506 interface? > > --Chuck > > > > ------------------------------ > > Message: 14 > Date: Sat, 30 Oct 2010 13:52:12 -0700 > From: alan canning <scanning.cc at gmail.com> > Subject: Need to find parts 82S23 / 74S188 > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Message-ID: > <AANLkTinzHd-NW1yL2LFuNG1=1q7s3hKOdxe2VLr7uXLH at mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Anybody no where to score some Sig 82S23 / Nat 74S188 parts ? I've tried > all > the usual suspects ( Ebay, local parts houses, Digikey, etc. ) with no > joy. > I believe this part was used on old S100 boards. > > Part also known as ( a.k.a. ) Fu 7111, AMD 27S18, MMI 6330, TI 18SA30 and > Harris 7602. Need this part to fix an old computer controlled RF Power > amplifier. > > Thanks for any and all help. > > Best regards, Steven > > > ------------------------------ > > Message: 15 > Date: Sat, 30 Oct 2010 13:54:40 -0700 > From: "Chuck Guzis" <cclist at sydex.com> > Subject: Re: Happy Birthday VAX 11/780 (influence of) > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Message-ID: <4CCC23A0.9876.E985BD at cclist.sydex.com> > Content-Type: text/plain; charset=ISO-8859-1 > > On 30 Oct 2010 at 15:34, Dave McGuire wrote: > >> I'd not consider it to be "memory-mapped I/O" at all, though, in >> the >> context of "a processor reading and writing I/O ports". Sure, file >> I/O is a sort of I/O, and mmap() and similar techniques map that file >> I/O into the address space, but the context of this discussion...and >> indeed, most, it not all use of the term "memory-mapped I/O" doesn't >> refer to this sort of thing. > > I'm sure and I'd never seriously call it "memory-mapped I/O"--but > sometimes our world seems akin to that of Humpty-Dumpty: "When I use > a word it means just what I choose it to mean--neither more nor less" > > Uh-oh, here comes another story... > > After I left CDC and the STAR project in 1977, my past came back to > haunt me in the form of doing an optimizing FORTRAN for the ETA-10 in > about 1983. We got a leased-line linkup to ETA in St. Paul and I > asked what text editor they were using. > > Much to my surprise, it turned out to be the same editor I'd written > for a lark around 1975 when the STAR had lots of really interesting > byte string instructions and I could exploit file-mapped I/O to use > them. Mind you, this was in the day of 16-line 1200 bps terminals. > > But the ETA-10 had none of those instructions, essentially having > evolved out of the "everything but the kitchen sink CISC" state of > mind of the original architecture. Some programmer had been detailed > off to replace all of those cool vector instructions with their > scalar equivalents! > > I was stunned and opined that with that way of thinking, the software > end of the ETA project was doomed. > > --Chuck > > > > ------------------------------ > > Message: 16 > Date: Sat, 30 Oct 2010 21:58:20 +0100 > From: Philip Pemberton <classiccmp at philpem.me.uk> > Subject: Re: DiscFerret: First working hardware, firmware and > microcode! > To: General Discussion: On-Topic and Off-Topic Posts > <cctalk at classiccmp.org> > Message-ID: <4CCC86EC.8040906 at philpem.me.uk> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 30/10/10 21:39, Chuck Guzis wrote: >> Also, aren't the read/write data signals on the SA1000 differential? >> Or do I have them confused with the ST506 interface? > > They're both differential. It's just that the SA1000 expects you to feed > it a reference clock signal. It doesn't have to be locked against > write-data, it just has to be there, and be accurate to 0.1%... > > Assuming the OEM manual is accurate, of course. > > -- > Phil. > classiccmp at philpem.me.uk > http://www.philpem.me.uk/ > > > ------------------------------ > > Message: 17 > Date: Sat, 30 Oct 2010 21:23:40 +0100 (BST) > From: ard at p850ug1.demon.co.uk (Tony Duell) > Subject: Re: TTL HEX LED driver chip > To: cctalk at classiccmp.org > Message-ID: <m1PCHxn-000J3xC at p850ug1> > Content-Type: text/plain > >> >> On 29 Oct 2010 at 22:10, Tony Duell wrote: >> >> > Anyother thought I had is to use a 7447 for the lower 8 or 10 >> > patterns (as it's designed to do!) and add logic for the higher ones. >> > I don't know if that saves chips. >> >> The 7447 has a problem in that the "6" doesn't have the top crossbar, >> so that it's indistinguishable from a "b". The '247 does include the >> top segment when displaying '6', which is why I mentioned the 247 and >> not 47. > > Yes, I should have remembered that... > > >> >> This brings to mind an ancient "fix" for the 47 "6" display--a >> pulldown diode connected between segment "e" and segment "a"--in the > > Been there, done that :-) > >> display of 0-9 there is no time when segment "e" is active that >> segment "a" isn't also active. The converse, however isn't true--and >> this "fix" will mess up your display of "b" if you use the method >> described previously to display 0-F. > > Of course. For 'b' you mmed the 'e' segment without the 'a' segment. > That's what distinguishes it from '6' > > >> >> But if you allow diodes, then there's no reason not to use a 4-to-16 >> demux and a mess of diodes to do the decoding for 0-F, is there? > > while my original question didn't preclude the use of discrete > components, and while I happly ageee that the odd diodes, pull-up > resisotrs, etc can lead to interesting solutions, I do feel that such a > diode matrix is outisde the spirit of the problem. After all, you could > say it can be solved with no ICs at all, just lots of discrete > transistors, etc. :-) > > -tony > > > ------------------------------ > > Message: 18 > Date: Sat, 30 Oct 2010 21:27:54 +0100 (BST) > From: ard at p850ug1.demon.co.uk (Tony Duell) > Subject: Re: Nuclear Data ND 6600 > To: cctalk at classiccmp.org > Message-ID: <m1PCI1t-000J3yC at p850ug1> > Content-Type: text/plain > >> eons ago at a TRW a friend bought a nice box that looked much like an >> ADM3a with nice case, integrated CRT and keyboard, and gleefully gave >> the guy selling it about $40 for it. This was in the day of $700 >> terminals new prices. >> >> It was a Vector graphics console. Unfortunately he had not looked at >> the back, or thru the cracks, but it was a plastic case with a keyboard >> and CRT inside, no PS, electronics or anything else. I suspect when he > > I am suprised there wasn't the standard driver circuits for the CRT (from > composite vidoe, say). My guess is that there should have been, and they > were msising. > >> moved east some years ago it got dumpstered, but it was about the same >> sort of thing, no brains in the "terminal" but in the box. > > ICL did something similar. They had 'terminals' that consisted of encoded > keyboards and composite monitors. The case was painted a horrible orange > colour ... I think I still have one of the keyboards somewhere, but I > mangaged to give the monitor away some years ago (thankfully...) > > -tony > > > ------------------------------ > > Message: 19 > Date: Sat, 30 Oct 2010 22:07:02 +0100 (BST) > From: ard at p850ug1.demon.co.uk (Tony Duell) > Subject: Re: TRS-80 Model II Manuals > To: cctalk at classiccmp.org > Message-ID: <m1PCIdm-000J4HC at p850ug1> > Content-Type: text/plain > >> >> On 30 Oct 2010 at 19:47, Tony Duell wrote: >> >> > ...And if they;'re not, it's most likelyto be the drive belt. Yes I >> > know 'up to speed' wasn't meant to be taken literally, but that seemed >> > too good to miss :-) >> >> Well, he could have a 220V 50Hz model and be running it on 120V 60Hz >> (the motor will develop sufficient torque to spin the disk). I've >> made that mistake once. The results from the reverse would be >> "interesting"... > > Actaully, a lot of the 8" drives I have have 120V motors, but of course > the right pulleys for 50Hz mains. They are run from an > (auto)transformer, often the primary winding of the syatem mains > transformer. > > So I suppose he could have something like that :-) > > -tony > > > ------------------------------ > > Message: 20 > Date: Sat, 30 Oct 2010 21:41:27 +0100 (BST) > From: ard at p850ug1.demon.co.uk (Tony Duell) > Subject: Re: TTL HEX LED driver chip > To: cctalk at classiccmp.org > Message-ID: <m1PCIF1-000J48C at p850ug1> > Content-Type: text/plain > >> >> On 2010 Oct 29, at 2:10 PM, Tony Duell wrote: >> > >> > For those who are wondeirng, the 'trivial' solution I mentioned uses 7 >> > off 74150 16-input multiplexers, one for each segment. You tie the >> > inputs >> > high low to determine if that segment is on or off for a given set fo 4 >> > input bits. >> > >> > After posing that, I thought of other solutions that make no >> > assumptions >> > about the segment patterns -- they always work. For example 7 off >> > 74151 8 >> > input muxes and a single inverter (1/6 of a 7404) That has the >> > advantage >> > of automatically providing actrive high and active low outputs. >> >> That only gives you 8 patterns, not 16 .. ? > > Err, no. That's what the extra inverter is for. > > You know hos to use a 2^n input mux to make an arbitrary combinartorial > function of n signals. Feed the n signals to the select inputs of the > multiplexer and wire the 'data' inputs high or low as the truth table > requires. > > But you can also yuse a 2^(n-1) input mux and maybe a single inverte, you > connect n-1 of the input lines to the select inputs of the mux. And then > for each of those combinations you consider the 2 truth table lines that > apply (the last input, the one you've not used yet, of course > distinguishes between the 2 lines in each pair). There are 4 possibilites > : > a) The output of the function is 0 in both cases (it doesn't depend on > the last input at all) --> wire that input of thr mux to ground > > b) It's 1 in both cases -> wire the input to Vcc > > c) It's 0, 1 , it follows the last input in this case -> Wire that last > input signal to the appropraite input of the multiplexer > > d) It's 1,0, it's the opposite of the last input. This is when you need > that inverter. Invert the last input signal and wire the appropriate > multiplexer input to the ouptu of the inverter. > > If oyu requre several functions of the same inputs (as here), you only > need 1 ivnerter (assumeing there are no fan-out problems), since it's > always thge same singal (say the 2^0 data input) you need to invert. > > Son yes, you can use 8 input multiplexers here (and 4 input ones if you > only want to generate 6 or 8 patterns). > > Now, another silly aside... > > If you want to use a 2^(n-2) mux, you may need any or all of the 16 > possible functions of the last 2 inputs (you split up the truth table > into sets of 4 lines, and see which function of the last 2 inputs gives > the right paattern, of course). This makes it less useful :-). But it's > made me think pof a chip that AFAIK never existed... If you think of those > 16 possible functions of 2 inputs, then 4 of them are 'trivial' in the > sense that you can produce them with no logic at all. Namely 'always 0', > 'always 1', 'equal to the A input' and 'equal to the B input'. Which > leaves 12 non-rtrivial ones/ Now that means there could have been a 16 > pin IC with 2 power pins, 2 inputs and 12 outputs, the 12 non-trivial > functions of the 2 inputs. Use that witha 74150 for an arbitrary fucntion > of 6 inputs... > > -tony > > > > ------------------------------ > > Message: 21 > Date: Sat, 30 Oct 2010 21:44:22 +0100 (BST) > From: ard at p850ug1.demon.co.uk (Tony Duell) > Subject: Re: TTL HEX LED driver chip > To: cctalk at classiccmp.org > Message-ID: <m1PCIHq-000J49C at p850ug1> > Content-Type: text/plain > >> >> On 29 Oct 2010 at 16:13, Brent Hilpert wrote: >> >> > I too realised that halfway thru the exercise and went scrambling back >> > to the databook to check on the 247. >> >> Another reason to lament the passing of the hardcopy databook. I >> used to sit and read them cover-to-cover. Not really possible in > > Absolutely. Of cousre I've kept all my old paper databooks, and still > read them from time to tieme. > > Yes, it's very useful being able to get data on just about any standard > IC over the internet. But it's useful in a different way being able to > flip through a data book, see what's available, etc. I've yet to find a > manufacturer's site that lets me browse in the same way. > > -tony > > > ------------------------------ > > Message: 22 > Date: Sat, 30 Oct 2010 21:48:01 +0100 (BST) > From: ard at p850ug1.demon.co.uk (Tony Duell) > Subject: Re: Wanted : Monitor Capable of TTL RGB > To: cctalk at classiccmp.org > Message-ID: <m1PCILO-000J4AC at p850ug1> > Content-Type: text/plain > >> >> On 30/10/10 03:08, Dan Williams wrote: >> > I am on the lookout for a monitor something similar to a Phillips >> > cm3388 does anyone near London have one they would like to sell or >> > trade, or know of anywhere I could get one. >> >> Surely you mean the CM8833? >> Those were fairly extensively re-badged -- Acorn, for instance, sold a=20 >> variant of the CM8833 Mk.II as the AKF17. > > Is CM8833 a TTL-input monitor? I think it was available as an option, > but most of them take analogue RGB on the SCART socket. > > Most of the time the SCART inputs, for all they're supposed to be 1V will > stand TTL (the CM8833 ones certainly will). Or since they're terminated > to ground through a 75 ohm resistor, connect a 300 Ohm (or so) resistor > in series with each TTL signal. Done that many times :-) > > Is there any reason a TV with a SCART socket isn't suitable? Most, if not > all, LCD and plasma TVs should haev RGB inputs on the SCART socket, for > example. > > -tony > > > > ------------------------------ > > Message: 23 > Date: Sat, 30 Oct 2010 21:52:09 +0100 (BST) > From: ard at p850ug1.demon.co.uk (Tony Duell) > Subject: Re: I/O models (was RE: Happy Birthday VAX 11/780 (influence > of)) > To: cctalk at classiccmp.org > Message-ID: <m1PCIPM-000J4BC at p850ug1> > Content-Type: text/plain > >> >> OK, it's fair to say that there's nothing that precludes memory-mapped >> I/O = >> in any machine (except perhaps physical memory architecture, although I >> can= >> 't think of an example). But port-mapped I/O machines had specific >> instruc= > > The obvious problem would be if the memroy map is already totally full. > If you've got a Z80 systme with 64K of memory, it would be perverse to > try memory mapped I/O (you could have some kind of MMU, but why...). > Similarky trying to emmeroy map any kind of I/O on a 2MByte PERQ would be > an 'interesting' exercise... > > -tony > > > > ------------------------------ > > Message: 24 > Date: Sat, 30 Oct 2010 14:09:44 -0700 > From: Brent Hilpert <hilpert at cs.ubc.ca> > Subject: Re: Fall cleaning, some small machines for free > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Message-ID: <981998b8f30737dece941bd3fc38a0c1 at cs.ubc.ca> > Content-Type: text/plain; charset=US-ASCII; format=flowed > > On 2010 Oct 30, at 1:36 PM, Bob Rosenbloom wrote: >> >> Panasonic NV-A960 VCR editing unit. >> http://www.anifur.com/clist/a960-1.jpg > > I dismantled one of these a few years ago, it contained an > (NEC-branded) 8080, a whack of NEC 8255's (PIO), half-a dozen ceramic > Fujitsu MB8516's (2K*8 EPROMS, 2716-like), all socketed, for anyone > that might take an interest in such stuff. > > >> All of these are located in the Santa Cruz, CA mountains, near the >> Bonny Doon airport. I can possibly bring something into Santa Clara >> where I work. Best to come visit and check them out here. I really >> don't want to >> ship anything as I just don't have the time or energy. >> >> Please rescue these before I scrap them, I really need the space and >> these are now outside, but covered under a Quonset hut. >> >> Bob > > > > ------------------------------ > > Message: 25 > Date: Sat, 30 Oct 2010 15:11:06 -0600 > From: ben <bfranchuk at jetnet.ab.ca> > Subject: Re: Need to find parts 82S23 / 74S188 > To: General Discussion: On-Topic and Off-Topic Posts > <cctalk at classiccmp.org> > Message-ID: <4CCC89EA.1000405 at jetnet.ab.ca> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > looks for 74S188 with google > http://www.futurlec.com/Memory/74S188pr.shtml > > > ------------------------------ > > Message: 26 > Date: Sat, 30 Oct 2010 14:17:16 -0700 > From: Geoffrey Reed <geoffr at zipcon.net> > Subject: Re: TRS-80 Model II Manuals > To: cctalk <cctalk at classiccmp.org> > Message-ID: <C8F1D96C.2E65E%geoffr at zipcon.net> > Content-Type: text/plain; charset="US-ASCII" > > Y'all are making me miss my tandy model 16 and 6000. > > > > > ------------------------------ > > Message: 27 > Date: Sat, 30 Oct 2010 22:21:08 +0100 (BST) > From: ard at p850ug1.demon.co.uk (Tony Duell) > Subject: Re: Need to find parts 82S23 / 74S188 > To: cctalk at classiccmp.org > Message-ID: <m1PCIrQ-000J3xC at p850ug1> > Content-Type: text/plain > >> >> Anybody no where to score some Sig 82S23 / Nat 74S188 parts ? I've tried >> all >> the usual suspects ( Ebay, local parts houses, Digikey, etc. ) with no >> joy. >> I believe this part was used on old S100 boards. >> >> Part also known as ( a.k.a. ) Fu 7111, AMD 27S18, MMI 6330, TI 18SA30 and >> Harris 7602. Need this part to fix an old computer controlled RF Power >> amplifier. > > IIRC, this is a PROM, 32*8 I think. Do you have a copy of the data to > program into it? A blank chip is not a lot of use to you otherwise... > > Also while all the derives you've mentioned are I think compatible when > being read (that is, as they are normally used in the circuit), the > programming algorithms are different for differnet manufacturers. You need > to get one that your programmer can handle > > -tony > > > ------------------------------ > > Message: 28 > Date: Sat, 30 Oct 2010 14:18:38 -0700 > From: "Chuck Guzis" <cclist at sydex.com> > Subject: Re: Need to find parts 82S23 / 74S188 > To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> > Message-ID: <4CCC293E.2099.FF7864 at cclist.sydex.com> > Content-Type: text/plain; charset=US-ASCII > > On 30 Oct 2010 at 13:52, alan canning wrote: > >> Anybody no where to score some Sig 82S23 / Nat 74S188 parts ? I've >> tried all the usual suspects ( Ebay, local parts houses, Digikey, etc. >> ) with no joy. I believe this part was used on old S100 boards. >> >> Part also known as ( a.k.a. ) Fu 7111, AMD 27S18, MMI 6330, TI 18SA30 >> and Harris 7602. Need this part to fix an old computer controlled RF >> Power amplifier. > > If you'd like something a bit closer to home, you might try ACP-- > they're listing some IM5603s on eBay for $7.95 the each. > > --Chuck > > > > End of cctalk Digest, Vol 86, Issue 68 > ************************************** ------------------------------ Message: 12 Date: Sun, 31 Oct 2010 11:37:47 +0100 From: Johnny Billquist <bqt at softjar.se> Subject: Re: Virtual memory To: cctalk at classiccmp.org Message-ID: <4CCD46FB.6070304 at softjar.se> Content-Type: text/plain; charset=ISO-8859-1; format=flowed On 2010-10-30 23:18, "Chuck Guzis"<cclist at sydex.com> wrote: > > On 29 Oct 2010 at 21:14, Johnny Billquist wrote: > >> > If your program vrites data to address 0, and reads it back, and get >> > the same data back, and another program on the same machine, at >> > roughly the same time, write to address 0, and reads the same data >> > back, and that data is different than the first programs data, then >> > I'd say you have virtual memory. > So, your definition ties virtual memory into multi-user access? > That's not the way I learned it. No no no. You miss my point. It don't directory tie in to multiuser access. It's about presenting to you a memory which in reality does not exist as you perceive it. As a follow on benefit of this is the fact that you can have multiple instances at the same time. But that is not the definition. The definition is that you appear to have a linear space of memory that maps the whole virtual address range, and that this memory is yours alone. It is your own private memory. Just as a virtual machine is your own private machine. No matter the fact that in reality, this is not the case, and your memory (or machine) is just something running under the control of an underlying operating system, which gives you this service. > Consider (again folks, I'm sorry for the reference) the CDC 6600 > (circa 1964). Every user is given a relocation address (called RA) > and field length (FL) as a way of partitioning main memory. Each > user's memory addressing space is kept isolated from every other's > and this fits your definiton because one user's location X was > different from every other user's location X and there was no way for > a user to tell what his RA was; i.e. each user was safely "boxed in". The important question here - are the programs aware of the RA register, and can they change it? And can they address the full range of memory addresses as perceived by the program. > That's not virtual memory by any stretch of the definition. Over- > committing memory meant writing/reading the entire FL of a user to > disk ("rollout" and "rollin"). Another word for swapping in and out? Anyway, I'm not sure if this would qualify as virtual memory or not without knowing a few more details. But it might very well be virtual memory, as far as I can tell. > Now consider the STAR-100 (I think it would qualify as the first > virtual memory machine of CDC), circa 1969. Defined by whom? CDC? Or you guys? ;-) > Every user got an > addressing space of 48 bits, but the machine itself had only > 512Kwords (64 bit) of physical storage. For production use, most of > the time the system was run in single-user mode (kept thrashing down > with large data sets). That fits my definition of VM because the > user was fooled into thinking that there was more physical memory > than there really was. You know, my definition and yours don't necessarily disagree on all points. Both would define the VAX as having virtual memory (well, except for the fact that yours might not, if you have a VAX with enough physical memory). We just disagree about what when there is more physical memory than you have virtual memory space. For you, that means it can't be virtual memory. but for me it can. For me, what is relevant is whether the program is presented with his own private memory space, which contains all addresses he can address, and where all those addresses are valid and working. A memory space which he don't have to share with anyone else. That's what virtual memory is, as opposed to physical memory, which you can point at, and which all running code on a computer needs to live on. And that means that the OS is always there. And possibly other processes as well. Using the same addresses you are. If that means that you cannot have your own memory for a specific address, then it's not virtual memory. But then you probably aren't talking about virtual memory either, but physical memory. > Aside from expanding program storage, the large addressing space was > used to map file space (another type of "memory-mapped I/O"), so file > access was actually performed through the paging hardware/software. > That was kind of cool, as the STAR was a memory-to-memory vector > machine, so you could use vector instructions on entire files, rather > than have to issue reads and writes for pieces of a file. > > So I think we differ considerably in our definitions. On some parts, yes. So, do the VAX not have virtual memory? After all, I can fill a VAX with more physical memory than you can address virtually. Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol ------------------------------ Message: 13 Date: Sun, 31 Oct 2010 11:47:53 +0100 From: Johnny Billquist <bqt at softjar.se> Subject: Re: Memory mapped I/O To: cctalk at classiccmp.org Message-ID: <4CCD4959.8040105 at softjar.se> Content-Type: text/plain; charset=ISO-8859-1; format=flowed On 2010-10-30 23:18, Brent Hilpert<hilpert at cs.ubc.ca> wrote: > On 2010 Oct 30, at 12:34 PM, Dave McGuire wrote: > >> > On 10/30/10 1:08 PM, Chuck Guzis wrote: >>> >> Aside from expanding program storage, the large addressing space was >>> >> used to map file space (another type of "memory-mapped I/O"), so file >>> >> access was actually performed through the paging hardware/software. >>> >> That was kind of cool, as the STAR was a memory-to-memory vector >>> >> machine, so you could use vector instructions on entire files, rather >>> >> than have to issue reads and writes for pieces of a file. >> > >> > That functionality is in use all over the place today as mmap(), >> > accessing files as if they were memory, pushing the read/write burden >> > out into the VM system. It's extremely effective. > I remember in the 80's (programming primarily on BSD (and VMS)) > thinking it would nice to have that functionality, how easy it would > make a lot of file-access programming, and that it would be easy to add > on a VM system. Of course, I was in ignorance of the prior histories > such as the STAR that Chuck mentions. A few years later a friend would > tell me about the new mmap function in unix. This might very well be totally wrong, but I remember hearing about it at the time, that Sun (who I believe was the ones to first implement mmap()) bascially took the whole TOPS-20 concept and translated it to Unix. A bit surprised no TOPS-20 hackers have spoken up yet... This was around for a long time on the PDP-10 before this. Not sure how it correlates timewise to CDC and the STAR though. But no matter if Unix took it from TOPS-20 or not, there is no denying that TOPS-20 had this a long time before it came to Unix. >> > I'd not consider it to be "memory-mapped I/O" at all, though, in the >> > context of "a processor reading and writing I/O ports". Sure, file >> > I/O is a sort of I/O, and mmap() and similar techniques map that file >> > I/O into the address space, but the context of this discussion...and >> > indeed, most, it not all use of the term "memory-mapped I/O" doesn't >> > refer to this sort of thing. > Well, Chuck did say "a type of". If files are a form of abstracted disk > I/O, then mmap is a form of abstracted memory-mapped I/O. Memory mapped files are kindof neat, but it's not I/O at all in one way. After all, all you do is just leave the actual I/O to the virtual memory system instead of doing it yourself. So it's not that the I/O is done in any different way, it's just initiated by someone else. Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol ------------------------------ Message: 14 Date: Sun, 31 Oct 2010 14:22:35 -0400 (EDT) From: "O. Sharp" <ohh at panix.com> Subject: Re: Repairing core memories.... To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Message-ID: <Pine.NEB.4.64.1010311349420.17597 at panix3.panix.com> Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed On Sun, 31 Oct 2010, Jos Dreesen wrote: > So I have these 2 PDP-8/L core stacks I am trying to recover: > > One would be perfect, if bit 3 @ adr 0 would be alive... > Although this is 99.99% OK, it is of course not good enough. Just to mke sure I'm hearing you right: Are you saying one individual core is 100% dead, and everything else is 100% okay? If so - if it's one single, individual core which is broken - I'd suspect this is pretty much irrepairable. The options would be to A) try to form/mold/create a new ferrite core around the wires, which would be insanely difficult assuming it could be done at all, or B) to unwire that plane of the core stack, replace the broken ferrite core with a new one, and then rethread/rewire it. That's extremely nontrivial work, I have to believe. But they were originally threaded by hand, albeit by people with microscopes and _very_ good eye-hand coordination and sewing skills, so it's within the realm of possibility. If I've read you wrong, though, and the whole thing is working except address 0 bit 3 is working _some_ of the time, that would be really good news. :) You could try scoping out the sense amps and inhibit drivers for bit 3 and see if they were just borderline to specifications, something which might be just tweaky enough to affect one bit. > The other stack seems to be a total loss : > 2 sense wires are open circuit, more than 20 select diodes shorted. Of > course the further quality of the cores is unknown. Oddly enough, this one might be easier to deal with. Have you tracked down where the sense wires go open-circuit? If they're failing at a solder-joint near an outer edge, you could potentially repair them without having to open up the whole damn stack. The diode replacement would likely mean partially disassembling the stack assembly to gain access to both sides of the diode PCB, but at least you're only having to dig in one level. O'course making those repairs might simply reveal more problems at the core level. But you've gotta start somewhere, I s'pose. :) > Is there any realistic way of getting one fully functional stack out of these > ? > > Removing a single core from the really bad stack to the almost OK stack would > seems almost feasible to me, since address 0 is bound to be on a edge of a > core mat. I suspect I'm not the only one on the list who: -thinks opening up a core-stack and repairing it is theoretically possible; -also thinks it would be a hell of a daunting project; -is somewhat amazed at the dexterity and patience of the people who originally hand-wired them at manufacture; and -thinks pulling off a repair of a core-plane by rewiring it by hand would give significant bragging rights. :) -O.- End of cctalk Digest, Vol 86, Issue 71 **************************************

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