test-drb

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101090 discussions

2716 with 100 nS access time - Lessons learnt by a Trainee Technical Officer in the dim, distant past...

by doug＠stillhq.com

Jos, You have sparked a funny (now) memory from my long distant past. In my youth, I had a Rockwell 65F11 SBC board, with a FDC, that was a small scale Forth development system. I spent many many hours writing code on it. One day, I decided that it needed a memory upgrade, and I designed a card to sit on top of the entire PCB that had buckets of ram (48K from memory??). As a trainee, I thought that I would be clever, an instead of laying out all of that tedious memory decode logic, I would use a 2732, and simply write a big decode matrix. (It worked beautifully for a traffic light controller state machine I did a little earlier...) So, I created an awesome memory upgrade PCB (with tape on film - 2 sided) - Photo reduce - expose - etch - drill - populate, etc, etc......All to discover that it didn't work.. After hours of trying to find the problem, I sheepishly approached one of the Senior Technical Officers, who suggested with a smile, that I connect a logic analyser to see what was happening... Low and behold - the CS* signal never got around to appearing before the memory was read. That day, I truly found out what 450nS access time actually meant. All to try to avoid mucking around with those pesky single use proms... Interestingly enough, a year or so later, I fitted one of those massive 62256 to get all of the memory I needed. Wo hoo. I hope you find a solution. BTW, does anybody remember the wierd diode logic decode that the TRS-80 model 1 used.... I tried that once as well, and discovered that you couldn't use silicon, and that only germanium worked. -- Doug Jackson, I-RAP, MAIPM, MIEEE Principal Information Security Consultant EWA-AUSTRALIA PO Box 6308 O'Connor ACT 2602 Level 1, 214 Northbourne Ave, Braddon ACT 2612 Tel: +61 (0)2 6230 6833 Fax: +61 (0)2 6230 5833 Mob: +61 (0)414 986 878 http://www.ewa-australia.com ============================================ IMPORTANT: This email remains the property of Electronic Warfare Associates - Australia. If you have received this email in error, you are requested to contact doug.jackson at ewa-australia.com or Ph +61 2 62306833 and delete the email. This message is not to be copied or distributed to other parties without the express permission of the author. Any personal information in this email must be handled in accordance with the Privacy Act 1988 (Cth). ============================================

18 years, 2 months

"CP/M compatible" vs. "MS-DOS Compatible" machines?

by ajp166＠bellatlantic.net

> >Subject: Re: "CP/M compatible" vs. "MS-DOS Compatible" machines? > From: Dave McGuire <mcguire at neurotica.com> > Date: Wed, 30 Jan 2008 13:27:25 -0500 > To: "General Discussion: On-Topic Posts Only" <cctech at classiccmp.org> > >On Jan 29, 2008, at 4:33 PM, Joshua Alexander Dersch wrote: >>> In the early-mid 80's a program was "well behaved" if it did it's >>> I/O thru DOS calls. Those programs would run on just about anything. >> >> Were there similar problems in the CP/M world? That is, was it >> commonplace for there to be CP/M programs that bypassed CP/M BDOS >> calls and wrote directly to a specific machine's hardware? Seems >> like CP/M developers were more disciplined in this fashion, but >> maybe it's just because in the CP/M arena there were so many >> different pieces of hardware it was the only way to do it? >> (Whereas with IBM, the PC was seen as more of a reference standard, >> even if it wasn't really that way in the beginning?) >> I'd be interested to hear opinions from people who were there at >> the time, since it was a little before my time. > > I was there; I was a CP/M weenie for many years. I still use it >from time to time; it's lots of fun. > > The CP/M BIOS definition doesn't provide for all the things a user >might want his/her hardware to do. Accessing serial ports >efficiently is one thing...Some popular CP/M communications programs, >such as the MODEM7 family, used the concept of "overlays" (not the >kind that we use in the PDP-11 world!), which are assembly language >modules which are written for your specific hardware that present a >unified (BIOS-like!) interface to the rest of the MODEM7 code. It >was intended that end users would write these routines for their >specific hardware. (in a day when end users were typically highly >technical people) > > Formatting floppy disks is another example. The CP/M BIOS has no >provision for floppy disk formatting, so a formatter program had to >be written for each floppy controller, and it accessed the >controller's registers directly to perform the formatting (and >sometimes verification) function. > > Other than specialized hardware (lab I/O, speech synthesizers, >real-time clocks) there weren't many instances of programs directly >accessing I/O in my experience. Another way to say that is if the application used BDOS calls there was a near 100% assurance of proper operation. If it did BIOS calls corectly that was near 100% as well. If it played with hardware direct all bets were off. Generally the hardware was simple enough that was a minor issue. The most common case was extra serial IO (modems and the like). Even then there is a YABUT.. If the system was IO interrupt driven and also fully implemented IObyte then doing modem IO was a easy task. The problem with that is CP/M didn't REQUIRE it but would certainly be nicer to use if you had it. Therein lies the statement: Most BIOS were minimal implmentations. It was the Ampro's, Kaypros, DEC vt180 and many others that were more than minimal BIOS and those you could actually count on more things as the bios did the lifting. Allison > -Dave > >-- >Dave McGuire >Port Charlotte, FL >

18 years, 2 months

got 80251 microcontroller PLCC 44 pin?

by jpero＠sympatico.ca

I was working on a monitor, this is romless version but I can take other type as long as I can jumper it to disable the internal programming. I'm fixing a monitor with a flaky 80251. Seems to have many pins output low clocked pulses/noies laid on the signals. The main filters are good, the linear regulators are clean and quiet. Got this microcontroller to spare? Cheers, Wizard

18 years, 2 months

ps2 to ascii keyboard converter

by elazzerini＠interfree.it

Hi at all, i'm working to make alive my bigboard 1. It has input for a parallel keyboard so I'd like to build or to know where to find an interface to convert a ps2 keyboard in parallel way. Well here <http://www.rasmicro.com/FTP/an434.pdf> http://www.rasmicro.com/FTP/an434.pdf there is a schematic to convert ps2 to IIC way. What I asking for is: 1) Is there anyone who know the way to modify the assembly to make the 8xc751 working on its p1.0 to p1.7 output to generate a parallel ascii code corresponding to the key pressed on the ps2 keyboard? 2) What could be the programmer to save the program onto the 8xc751? Thanks Enrico

18 years, 2 months

YouTube videos of vintage PDP-11/40, ASR-33, VT05, etc

by wacarder＠earthlink.net

Somebody recently was asking about wanting to see videos of some vintage equipment in action. I have uploaded some videos to YouTube. These were taken some time back in 2007 one day when I was playing around with my system. The videos are not anything high quality, but do show the PDP-11/40 front panel with the lights blinking, the RL01, RL02, and RK05 drives as they are running, and an ASR-33 teletype, a VT05 terminal, a VT52 DecScope, an LA36 DecWriter II, and an LA120 DecWriterIII as the terminals run the system status program $SYSTAT. Take a look at some live vintage equipment in actions! The URL at YouTube is under the user "WoffordWitch" at: http://www.youtube.com/profile_videos?user=WoffordWitch&p=r If there's anything in particular anyone would like me to video and upload, just reply here or email me at wacarder at usit.net, and I'll fire up the old system and try to accomodate you. Thanks, Ashley Carder http://www.woffordwitch.com

18 years, 2 months

some free DEC boxes in boston area - pickup only

by josecvalle＠gmail.com

Zane.. Hello, from Computer Museum Brazil. I am curator of Museu do Computador , my name Jose Carlos Valle, I will apreciatte to pick up. Please could you send photo of that material? I would like to get it to my Museum here in Brazil. But, I have a friend mine in Dallas, TX, Richard, he will get it and will send to me. Thanks Jose Carlos Valle http://computermuseumbrazil.blogspot.com www.museudocomputador.com.br 2008/1/30, Zane H. Healy <healyzh at aracnet.com>: > > At 1:09 PM -0500 1/30/08, Brad Parker wrote: > >- working BA123 cabinet (with wheels!); no disks, no floppy, no boards, > > no front panel. I think I have the sides, no guarantee. But the p/s > > works fine. Great if you need an open qbus chassis. Plus makes a > nice > > coffee table. > > If you've got all the sides and intact wheels, this is well worth > saving. Even if it is for a VAX, nothing says someone can't > "upgrade" it to a PDP-11. I'd classify it more of an end-table > personally, and I actually used one that way for a few years. > > With a little effort you can also keep a VT420 and LA75 on top of it > and use both. > > Zane > > > -- > | Zane H. Healy | UNIX Systems Administrator | > | healyzh at aracnet.com (primary) | OpenVMS Enthusiast | > | MONK::HEALYZH (DECnet) | Classic Computer Collector | > +----------------------------------+----------------------------+ > | Empire of the Petal Throne and Traveller Role Playing, | > | PDP-10 Emulation and Zane's Computer Museum. | > | http://www.aracnet.com/~healyzh/ | > -- Jose Carlos Valle Museu do Computador & Futuro da Tecnologia tel:+5511-8609-7410 Brazil

18 years, 2 months

How compatible were "MS-DOS Compatible" machines?

by cclist＠sydex.com

> Date: Wed, 30 Jan 2008 11:07:38 -0600 > From: Jim Leonard > > In the early days, it was possible to call BASIC subroutines. But, I > > don't think that they kept the same addresses for long. > > Wow -- while that's cool, what was a useful application for that? > Borrowing the use of the floating-point routines, perhaps? ROM has a > faster access time than RAM, but would it have been all that much faster > than doing it yourself, or would it have just been merely convenient? Any IBM system with BASIC-in-ROM kept the same addresses for subroutines throughout the life of that feature. That's why you can run PC-DOS BASICA only on those machines having the ROM BASIC. For generic MS-DOS, MS supplied GWBASIC as an option (which I still use on my XP-equipped machine when I need to do some quick figuring). Several very early games required BASIC-in-ROM--the basic 5150 shipped with 48K of DRAM, so memory was at a premium. I don't think any productivity tools made use of the ROM BASIC, however. Do any of the IBM diagnostics use it? Cheers, Chuck

18 years, 2 months

some free DEC boxes in boston area - pickup only

by brad＠heeltoe.com

Hi, I don't need the following DEC equipment anymore. Since I got them for free I figured I'd pass them on if anyone wants them: - working BA123 cabinet (with wheels!); no disks, no floppy, no boards, no front panel. I think I have the sides, no guarantee. But the p/s works fine. Great if you need an open qbus chassis. Plus makes a nice coffee table. - MV4000; has cpu & some disks (2 or 3?) it booted vms once and may still. I may have some s cards also laying around (nothing exciting). Worked fine last time I powered it up. Marginal as a coffee table; perhaps an end table. - MV3100 + associated scsi disk box. Last ran netbsd and worked fine. No idea what is on the disks. I think I have one scsi cable also. Not tall enough to be a coffee table. too heavy to server as paper weight. I can't ship these. If you want them you need to pick them up. I'm in Arlington Mass (USA) 02476. You can pick them up most any time. (I can't get at my 14" disks right now and those need to be spun up :-) -brad

18 years, 2 months

Z80 Divide by 10

by cclist＠sydex.com

On 25 Jan 2008 at 12:00, cctalk-request at classiccmp.org wrote: > I figure that one might do part of the multiplication and then > right shift the result some since were are going to truncate the > LSBs anyway. The first result is expected to error some. With > the correct value for the multiply, the error will always be on > the low side, keeping the error calculation simple. The largest > error seems to grow linearly so even with some truncation, > one should be able to hit 10K or so with only 1 or2 conditionals, > using a large fractional munber to multiply. > I don't think I'd ever use this but it was fun to think about. I suspected that this is what you might be doing (that ADD HL,H really had me wondering), but I wonder if your method will hold together for accuracy or be faster than a simple unrolled 10 bit divide. Remember that without the need for an iteration test you can use BC to hold the scaled +10 and use a DAD instead of an SBC, shaving a byte from the loop. Cheers, Chuck

18 years, 2 months

DEC Highnote P8x

by steve51158＠hotmail.com

Hi sorry to bother you,I came across a CCtalk archive from Nov 2003 regarding power supply pin out connections for a DEC Highnote notebook.I have recently aquired one of these but have the same problem,no power supply,I have an old non working DELL adapter which looks to have the same connector so if you still have the info on the connections that would be a big help,thank you. _________________________________________________________________ Share what Santa brought you https://www.mycooluncool.com

18 years, 2 months

.. 1973... Intertechnique Multi 8 / Microdata 800-1600

by pichotjm＠free.fr

Hi, Thanks for information. I have added your comment on my http://pichotjm.free.fr/Multi8/Multi8.html page. Do you accept that? I have found 2 more photos showing me working with another Multi 8 configuration, but i have to restore them (many scratches, white dots...)! May be from 1972. I was debugging one of these applications: http://pichotjm.free.fr/Techno73/Applis/Applis.html Electronic contains the first microprocessor 4004. Unfortunatly, i have no document about this. JMP

18 years, 2 months

Help needed on a DEC LA180 printer

by RodSmallwood＠mail.ediconsulting.co.uk

On switch on the printer will seek the margin. If there's a problem with the position encoder or photocell the motor will not stop. With the printer off make sure the head carriage is free to move and the bar it slides on is not bent. You can put a little oil on the head slider bar. As with above if the head jams before it gets to the rest position. The stall current from the motor will trip the alarm. Rod Smallwood DEC Terminals Product Line 1975 - 1978 -----Original Message----- From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org] On Behalf Of Harten Sent: 29 January 2008 20:25 To: cctech at classiccmp.org Subject: Help needed on a DEC LA180 printer Hi! I'm a Computer collector from Germany and the last 3 years i spend a lot of time in reconstructing and repairing my PDP11/05 along with its peripheral devices (2x RK05,RX02,BA11ES). Noe that these things are working im trying to repair my LA180-PD printer, that was in no good condition. With a copy of the logic-prints i was able to find some faulty IC's on th logic board- but there must be at least one more. On Power-Up the carriage starts to move back to left edge but stopps before reaching the left end then the bell is turned on permanently. There is no reaction on any button pressed or switched over. Unfortunately i have no Maintenance Manual or Logic description, maybe there is a person out on this list who can help me with a copy of the documents. Regards Axel Harten.

18 years, 2 months

old ncr laptop

by jwest＠classiccmp.org

I was contacted by someone with an NCR 3120 laptop (1990). They want to sell it for best offer plus shipping. It's located in arizona and from the pics looks to be minty. If anyone is interested, please contact me off-list. Jay

18 years, 2 months

Has anyone ever written a standalone Commodore disk drive emulator?

by ethan.dicks＠usap.gov

Hi, Commodore folks, I have just tracked down an ISA IEEE-488 card and was thinking that it might be interesting to use it to build an older PC into a Commodore diskette drive emulator - I recall there are various projects to interface modern hardware to PETs (like the C2N232 I have with me), but the idea in this case is to allow existing apps to work as if there were a real C= drive hanging off the PET's IEEE port. Essentially, the PC would act as closely to, say a 4040, as possible. My thought was that if I had a real IEEE-488 interface, it could handle the physical-layer protocol, and the emulator would only have to handle sending and receiving command strings and data. The virtual diskettes would be, of course, image files. I'm not really as worried about RELative files - more along the lines of "direct access" files where the code running on the PET wants to read and write individual sectors, ignoring the C= DOS filesystem. That is, in fact, the major reason for trying to emulate drives in the first place - if it was just a case of loading and saving streams of data as files, the C2N232 does a fine job of that (and costs on the order of $10 to breadboard). There seem to be a number of ways to emulate C= IEC-bus devices (such as the 1541-III), but not for the IEEE-488. If anyone can point me at any existing projects, even if they are incomplete, it would be a big help. Thanks, -ethan -- Ethan Dicks, A-333-S Current South Pole Weather at 30-Jan-2008 at 02:00 Z South Pole Station PSC 468 Box 400 Temp -34.8 F (-37.1 C) Windchill -57.9 F (-50.0 C) APO AP 96598 Wind 7.9 kts Grid 45 Barometer 674.7 mb (10829 ft) Ethan.Dicks at usap.gov http://penguincentral.com/penguincentral.html

18 years, 2 months

DG10 AOS tapes

by mnusa2＠hotmail.com

I have some DG10 AOS tapes which I can not use and do not need. I have not tested these tapes or contents. 8 pcs of 45 MB QIC-2 tapes. If any interest please email. _________________________________________________________________ Windows Vista + Windows Live. Astu digitaaliseen maailmaan. http://get.live.com

18 years, 2 months

Z80 Divide by 10

by cclist＠sydex.com

> Date: Tue, 29 Jan 2008 06:45:46 -0500 > From: M H Stein > >Some people get rather upset at the lack of symmetry, and lack of certain > >instructions that might be handy, such as a load immediate into segment > >registers. > And some people just get rather upset by _anything_ that doesn't match > their view of how the world "should" be... Sigh. As long as it's possible to "get there from here", I don't much mind how an instruction set's laid out. I'll learn it and learn to work around the problem areas, such as the lack of an inclusive-OR instruction on the CP1600, or the weird setup of the RCA COSMAC, or the asymnetry of <fill in the blank>'s instruction set, or the lack of a hardware stack on a PDP/8. If you want strange and asymnetric, try working with a few samples of the current crop of microcontrollers. You can get used to anything. In a way, this line of discussion reminds me of an Inuit criticizing the Tongan language for the lack in the vocabulary for different types of snow. You work with what you've got. Cheers, Chuck

18 years, 2 months

Fast 8Kx2 ROM replacement

by cclist＠sydex.com

> Date: Mon, 28 Jan 2008 14:49:18 -0500 (EST) > From: Jeff Jonas > Why not try for a free sample of the Freescale Magnetoresistive Random > Access Memory (MRAM): it's fast and needs no power at all. The largest > seems to be P/N PR2A16AVYS35 4MBIT I was also going to suggest the Ramtron FRAM, but was looking for something close to the OP's original target of 2Kx8. The smallest parallel-access FRAM that Ramtron offers is 8Kx8, which is why I didn't suggest it. Cheers, Chuck

18 years, 2 months

8-bit micro MMU's

by cclist＠sydex.com

> Date: Tue, 29 Jan 2008 01:19:35 -0500 > From: Dave McGuire > A slight diversion here...What is wretched about the 8202? I ask > because I got ahold of a few not long ago (and some 8203s) and was > considering putting something together with them to play with. As I recall, the timing, on chip-to-chip samples was all over the place making it a headache to design a manufacturable product. The second-generation 8203 is much better in that respect. I'd recommend that you skip the 8202. If it's a one-off and you have more than one sample, it may not matter. I thought it interesting that IBM avoided the problem of a DRAM controller altogether on the PC and dedicated a channel of the 8237 DMA controller to serve as refresh generator. You'dve thought that Intel would have made them a great deal on one. Cheers, Chuck

18 years, 2 months

a tad OT: creating a bootable cflash card

by chrism3667＠yahoo.com

I'm stumped. All I have to work with is a WinXP laptop that doesn't boot off anything special in particular. The CD drive yes, but that's about it. I once was able to make bootable CD's w/early versions of Norton, but I doubt that would work for a compact flash card. I had thought I could "format/s" inside a dos box...no dice. even the "format" option arrived at by right clicking doesn't allow you to create a bootable partition. apparently "fdisk" doesn't exist in XP. I don't even have my USB floppy drive handy. Not that I would imagine DOS 6.22 would recognize a PCMCIA slot. Is there a way of running an *alien* DOS within XP. In a DOS box in other words? No, I don't imagine so. Whenever you click on a foreign command.com, you get a "wrong version" message or something. No I don't have the WinXP embedded resource kit (there's a program called bootprep that allegedly might help). I'm not trying to work with XP, just utilize it to create a DOS-bootable device. help ____________________________________________________________________________________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping

18 years, 2 months

Anybody ever find Kai Kaltenbach?

by tshoppa＠wmata.com

I was trading some stuff with Kai Kaltenbach back around 1996/1997 or so, and promised him a binder of docs when I found it. Well, I found the binder, and now I cannot track him down. Anybody have a current E-mail address for him?

18 years, 2 months

Z80 Divide by 10

by ajp166＠bellatlantic.net

> >Subject: Re: Z80 Divide by 10 > From: Sean Conner <spc at conman.org> > Date: Mon, 28 Jan 2008 19:35:52 -0500 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > >It was thus said that the Great Jim Leonard once stated: >> >> I find it amazing that there's an instruction set even more annoying >> >> than >> >>the 8086 (segments and all). I was amazed at the lopsidedness of the >> >>instruction set. I'm beginning to think I was lucky in skipping this >> >>particular chip (my first 8-bit was the 6809, so I think I got spoiled). >> >> Other than the goofy segment layout, what did you find "annoying" about >> the 8086 instruction set? > > Me? I didn't find it all that odd (at least, once I realized it was >better to look at the opcode map in octal instead of hex), but I do recall >reading various rants against the x86 on USENET in the early to mid 90s. I >did *a lot* of 8086 programming in the late 80s/early 90s, and still like >revisiting it from time to time (well, assembly in general, not specifically >the 8086). > > -spc (Man, I think I'd prefer the 6502 over the Z80 any day, and I hate > the 6502 ... ) ;) Having programmed a lot of the 8bitters and a fair number of 16 bitters my favorites are: PDP11, z80, 8085 and 804x(and 805x) I happen to hate Zilog neumonics for z80 though as it hides the fact that thre are hole in the instruction set. It also took me a long time to to switch from octal to hex as octal made the instruction set clear rather than hiding the holes. But I'm used to them especially the 8085, z80 and 804x. Others I find interesting are 6502, 1802, 6809 and TI9900 but I have to pay atttention as they require a different programming approach than would z80 or for that fact PDP11. Not better or worse just different. My all time favorite is PDP-8. Likely the most minimal instruction set that does enough. It has all the lacks XYZ of most every cpu and you can still code effectively with it. Also after PDP-8 everything looks good. ;) The 1802 also falls in that catagory, odd little machine with not much there but functional programs that are fast for the CPU speed manage to happen. There are few micros that do decent math, ti9900 and 6809 are ok at it but none were designed to be a primary number cruncher. Most code math routines effectively enough and thats what counts. If theres a comment here each cpu has something going for it or PDP8, PDP-11, z80 and 6502 would not have been amoung the longest lived cpus going. Yet despite that I still loathe the 8088/6 and later as the worst 8080 enhancement with a bag on the side. Just my .02$ Allison

18 years, 2 months

8-bit micro MMU's

by ajp166＠bellatlantic.net

> >Subject: Re: 8-bit micro MMU's > From: Dave McGuire <mcguire at neurotica.com> > Date: Tue, 29 Jan 2008 01:19:35 -0500 > To: "General Discussion: On-Topic Posts Only" <cctech at classiccmp.org> > >On Jan 28, 2008, at 3:02 PM, Chuck Guzis wrote: >> With the slow memory chips back then, making things work with the >> wretched 8202 DRAM controller was a real chore. I seem to recall >> that if you ran worst-case numbers, you could wind up with the >> requirement of a negative access time for the DRAM for a 5MHz 8085. >> Adding bank-mapping hardware in the address path didn't improve >> things any. > > A slight diversion here...What is wretched about the 8202? I ask >because I got ahold of a few not long ago (and some 8203s) and was >considering putting something together with them to play with. Nothing save for the 8202 was optimized for 16k drams and the 8080 cpu (at 2mhz!). It was the older part. if your going to do Dram larger than 64k that the 8203 is the part of choise and pretty decent though not fantastically fast. the latter was because early Dram didn't do cas/ before ras/ refresh and other tricks to interleve the refresh cycle and the early parts were slow. > I worked with the 8207 DRAM controller extensively on the Navier- >Stokes Supercomputer Project at Princeton in the mid-late 1980s...We >had lots of problems with the memory arrays at first, but they were >eventually all traced to power...both nasty spikes on Vdd and ground >bounce. Big arrays are tough in the power gridding and bypass. The 8207 was a more involved part to use. Allison > > -Dave > >-- >Dave McGuire >Port Charlotte, FL >

18 years, 2 months

Z80 Divide by 10

by dm561＠torfree.net

Date: Mon, 28 Jan 2008 15:11:42 -0800 (PST) From: Fred Cisin <cisin at xenosoft.com> Subject: Re: Z80 Divide by 10 >>> Can we just shoot the designers of the 8086 and just leave it that. !? On Mon, 28 Jan 2008, Jim Leonard wrote: >> But seriously -- why? I didn't find it all that horrible -- in fact, I >> missed the string handling (REP MOVSW/STOSW/SCASW/etc.) on all the other >> platforms I mentioned. If they truly deserve to be shot, I want to know >> why :-) >Some people get rather upset at the lack of symmetry, and lack of certain >instructions that might be handy, such as a load immediate into segment >registers. ---- And some people just get rather upset by _anything_ that doesn't match their view of how the world "should" be... m

18 years, 2 months

non-existence of printer collectors...proven wrong

by Arno_1983＠gmx.de

Sat, 26 Jan 2008, "Chuck Guzis" <cclist at sydex.com> wrote: > Okay, so who wants a working Diablo Hitype II? Spare wheels and >(probably dried-out) ribbons. Free for pickup, or for the cost of > shipping. Probably in America and thus out of my reach, unless somebody coming to the upcoming VCFe in Munich offered to bring it along. "Ed" <listmailgoeshere at gmail.com> wrote: > Back in 1995 I used an IBM 3262 belt printer which was attached to an > AS/400. I don't know what its native interface was, but the company I > was working for had got hold of a third-party interface box that was > mounted on the side of said printer and connected it to the AS/400 via > twinax. Funny thing was, there was also a Centronics socket on the > base of said interface unit... > That unit would do 600LPM, so I was told. It was about a 1m x 1m x 1m > cube, and it was *loud*. Ah, I totally forgot about telling that I at one time also was involved with the rescue of such a setup (3262 and interface box) from a big mailorder store in Germany, which was passed to Hans Franke for possible future use with his/our 4331. The print server or how it's to be called boots from a floppy disk on power-up. The printer had been transported to my school in the Janitor's van and stored there for some weeks. When we came to pick it up in with our station wagon, it showed that the unfortunate piece of equipment was a tiny bit too large to fit through the hatch although there would have been ample space inside. We solved the problem by rolling the printer to our garage on it's own casters (one block from the school) and taking off the outer panels there so we could deliver it to Munich the following weekend. In my list, I forgot to mention my only GPIB-enabled printer, a CBM 8023 (9 needles, IIRC). At the risk of leaving the classic definition of "printers", I also have to brag about last week's great find, an Agfa PCR II film recorder, unfortunately missing the camera body that belongs to it - a modified Nikon N6000, according to internet sources. So long, Arno -- Arno Kletzander Student Assistant // Studentische Hilfskraft Informatik Sammlung Erlangen www.iser.uni-erlangen.de GMX FreeMail: 1 GB Postfach, 5 E-Mail-Adressen, 10 Free SMS. Alle Infos und kostenlose Anmeldung: http://www.gmx.net/de/go/freemail

18 years, 2 months

8-bit micro MMU's

by cclist＠sydex.com

> From: Alexis > Subject: 8-bit micro MMU's > Maybe someone can use this? I haven't looked deeply into the MP/M II > XIOS requirements so I may have left something out that it needs so is > anyone familiar with the XIOS? (Raises hand) For MP/M and CP/M Plus, this is probably far too elaborate. It's my experience that MP/M appears to be designed around the idea of a 16K bank size. So, for 256K, you need only to be able to select 16 banks of 16K. A fairly common 74LS670 should do the trick. A 74LS610 or 612 should be more than adequate for most large-scale MP/M applications, but I understand that they're getting hard to come by. They can sometimes be found on early 286 motherboards as the DMA bank select register. (PC XTs and ATs have to perform bank-selection for DMA, as they use an 8237 DMA controller model, which is limited to 64K addressability). I made the mistake of (just before the '610 came out) designing a bank-select circuit for an 8085 product. It used a Fairchild 64x9 bipolar RAM (power-hungry and expensive) to give granularity of 1K pages. With MP/M, this was overkill. 16K would have done just fine and saved time and money. With the slow memory chips back then, making things work with the wretched 8202 DRAM controller was a real chore. I seem to recall that if you ran worst-case numbers, you could wind up with the requirement of a negative access time for the DRAM for a 5MHz 8085. Adding bank-mapping hardware in the address path didn't improve things any. The comment about separating data and address space is worth considering, but be aware that, because of deficiencies in the instruction set and for performance and space needs, 8080 self- modifying code is not uncommon. For example, consider the problem of I/O to a variable port number. SHLD-ing into the operand field of an LXI instruction to save a few cycles and bytes is also common in my experience. For what it's worth. Cheers, Chuck

18 years, 2 months

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