test-drb

test-drb@ccmp.vtda.org

101090 discussions

by jos.mar＠bluewin.ch

Is there a way to coldboot an apple III, if you do not have the SOS disks ? On the apple II you can do it via the serial interface and the Basic ROM, but the apple iii lacks these ROM's Jos DReesen

18 years, 5 months

Babbage Calculating Machine Article 1833

by billdeg＠degnanco.com

New York Weekly Messenger 2-13-1833 Babbage Calculating Machine Article 1833 On the back page of this newspaper is an article that describes in some detail the eye-witness account of a *working* machine: "...the greater part of the calculating machine is already constructed....I have had the advantage of seeing it actually calculate, and of studying its construction with Mr. Babbage himself..." Does this account describe a working computer? To help make this determination I would want to learn more about the error checking capability of this machine, which I assume was used for calculation of significant digits. A described, Babbage's calculating machine could be described as "computer-like" at least. I believe that this article reports the closest Babbage got to a actual working computer. Or just an elaborate calculator. There are no references in the article to what we today would identify as punch cards or programming. Download the PDF http://www.vintagecomputer.net/babbage/charles_babbage_2-13-1833.pdf ...and read for yourself. The article describes error checking and how results are viewed and how log tables could be calculated accurately, for use in astronomy. The article noted that regarding the printer "..less progress was made...". In the 1830's news from Europe would take a few weeks to reach New York, as boat was the only cross-Atlantic communications. Most articles in the paper refer to end of December 1832 events, including the account of the Calculating Machine. Overall there was a lack of contemporary articles about Babbage's calculating machine in 1832-35. I was able to find just the one often quoted article by D Lardner: "Babbage's Calculating Engines" from the Edinburgh Review 59 (1834) pg 263-327. The New York Weekly Messenger article above was printed a year prior, making it among the first known articles about Babbage's calculating machine. The apparent lack favorable press and the loss of funding in 1834 obscured the fact that the machine had a working visual "display" and was probably more complete than people realize. Was the calculating machine programmable? Maybe. Most writings about the Babbage projects were published a generation after the project was cancelled and I don't think that it's possible to discount the notion entirely.

18 years, 5 months

*updating* 8088's

by dkelvey＠hotmail.com

> From: rdawson16 at hotmail.com > > >> Date: Mon, 26 Nov 2007 13:15:02 -0500> From: ray at arachelian.com> To:> Subject: Re: *updating* 8088's>> Roy J. Tellason wrote:>> On Friday 23 November 2007 19:05, dwight elvey wrote:>>>>>> From: rtellason at verizon.net>>>>>>>> I notice that even those guys that are building relay computers "cheat">>>> and use a single small solid-state chip for RAM. :-)>>>>>>> Hi>>> I've been thinking about how one could make a reasonable>>> memory, using small reed relays. If one puts a magnet close>>> to one end, it will cause the reed to close. Move it back>>> some and it will hold until the field is too weak.>>>> ..>>>> Dunno if they still sell them or not, but Radio Shack used to sell a pack of>> 20 reed switches for only a couple of bucks...>>>>>> Hmm... Wonder if it's possible to build a relay without a spring on the> switch. That is, you have to send current with one polarity to set the> switch to a 1 and reverse polarity to set a zero - sort of what core> memory does with rings... I suppose this could instead be done by> attaching a magnet to the switch, or using magnet as the thing inside> the switch body, or better yet maybe a relay with a ball with a set of> contacts as the switch and two magnets, one on each opposite side...> you'd energize one coil for a "1" and the other for a "0">> Hmm, could even be done with a solenoid and use the mechanical part of> it to touch a wire for output. :-) Wouldn't really be a relay, but> pretty close.>> > > > Teledyne makes a 'non volitale' relay. its tradename is Maglatch. Hi Randy I used to use these or similar in equipment while I was in the service. They were not real reliable and expensive. They were in a state machine control for a reel to real multi track tape. Every now and then we'd take the control board out and smack it several times onto the work bench. It would work fine for a few weeks and then need another smack. I assumed that it was related to the armatures needing to be demagnetize every now and then. They used a bias magnet similar to what I've been suggesting to work with reed relays. One thing I learned about reed relays is to not use a weller iron with the magnetic heater switch. The reed relay would not open. I'd use that method if it was more controllable. Dwight _________________________________________________________________ Put your friends on the big screen with Windows Vista? + Windows Live?. http://www.microsoft.com/windows/shop/specialoffers.mspx?ocid=TXT_TAGLM_CPC…

18 years, 5 months

*updating* 8088's

by ajp166＠bellatlantic.net

> >Subject: Re: *updating* 8088's > From: Dave McGuire <mcguire at neurotica.com> > Date: Tue, 20 Nov 2007 11:43:02 -0500 > To: "General Discussion: On-Topic Posts Only" <cctech at classiccmp.org> > >On Nov 19, 2007, at 11:03 PM, Allison wrote: >> I build with 6 and 10mhz z80s and 12mhz 8085s I have and theres >> little problem with finding static rams and Eprom (and EEprom) >> that can keep up. > > Did you say 12MHz 8085? Holy cow! Tell me more? I meant 6MHz, 12mhz crystal. However, even at 6 its fast. FYI I tried overclocking a 80C856mhz part and it was still doing well at 8mhz but I was seeing memory timing issues. You don't see the 6mhz parts too often. The usual is the 3 and 5mhz and usually the -5 (5mhz) will overclock to 6 with no real issues. At those speeds it's intereating as old 8080 software is now at 3X! Though a 10mhz Z80 is also a nice thing but the 85nS memory need is something to aware of. That short M1 read cycle preally beats up ram. Z180 is better and Z84S180s can be found as fast as 33mhz. Allison > > -Dave > >-- >Dave McGuire >Port Charlotte, FL >Farewell Ophelia, 9/22/1991 - 7/25/2007 > >

18 years, 5 months

Northstar Dimension

by chrism3667＠yahoo.com

Not exactly my Holy Grail, but a unit I hold in high regard. Anyone have one (or more) surplus to their needs (working or not). I actually have a line on one already, but the guy is taking his time. Don't want to bug him that much. ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs

18 years, 5 months

2708 EPROM progreammer - old magazines designs

by dm561＠torfree.net

-----------------Original Message: Date: Thu, 29 Mar 2007 07:48:55 +1000 From: Doug Jackson <doug at stillhq.com> Subject: Re: 2708 EPROM progreammer - old magazines designs John S wrote: > > As 2708s are obsolete few moern programmers support them, apart from a few > > that cost many $100s. So I thought why not try and build one? I've found > > references to the following classic magazines, and I would be willing to pay > > a small fee for photocopies or scans of the articles: > > > > Program your next EROM in BASIC. Schematic for a 2708 erasable read only > > memory reader and programmer which uses parallel IO ports to set data and > > address. The software to drive the programmer is written in BASIC. > > Byte - March 1978 page 84 on (main article) > > Byte - April 1978 page 62 (Byte Bugs) > I have a programmer designed by Steve Ciarcia from BYTE - It uses an 8051AH-Basic (The 8051 with basic embedded) as the controller - and still works a treat - to this day. - Standalone board, interface via serial. It was fun to see peoples faces when you shipped a ^C down the serial line, and dropped through to a READY prompt. I can find the doco for yo, but it is a high end solution to a simple problem. Alternately, I'm more than happy to read an eprom for you, and email contents - I'm in Oz though. Perhaps there is somebody in the US who could do the same. Doug -----------------Reply: I have one of those as well; alas, it does NOT do 2708's. To the OP: I can scan the KB article for you, but the 2708 programmer is intended to work with a Motorola MEK6800-D2, and consists of nothing more than 3 transistors to switch the 27V (and a couple of switches and a socket for the EPROM). It's all done in software. mike

18 years, 5 months

Sega YENO

by chrism3667＠yahoo.com

Anyone got one? ____________________________________________________________________________________ Be a better sports nut! Let your teams follow you with Yahoo Mobile. Try it now. http://mobile.yahoo.com/sports;_ylt=At9_qDKvtAbMuh1G1SQtBI7ntAcJ

18 years, 5 months

strange request (Sharp PC-7000)

by chrism3667＠yahoo.com

Does anyone have a NOS screen for one of these things? I turned mine on today and I like it, but it's a bit worn out. Strange request it may seem, but I actually have a brand new screen and k/b for IBM's first laptop (I can't believe the name escapes me). ____________________________________________________________________________________ Be a better pen pal. Text or chat with friends inside Yahoo! Mail. See how. http://overview.mail.yahoo.com/

18 years, 5 months

*updating* 8088's

by ajp166＠bellatlantic.net

> >Subject: Re: *updating* 8088's > From: Ray Arachelian <ray at arachelian.com> > Date: Mon, 26 Nov 2007 13:15:02 -0500 > To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> > >Roy J. Tellason wrote: >> On Friday 23 November 2007 19:05, dwight elvey wrote: >> >>>> From: rtellason at verizon.net >>>> >>>> I notice that even those guys that are building relay computers "cheat" >>>> and use a single small solid-state chip for RAM. :-) >>>> >>> Hi >>> I've been thinking about how one could make a reasonable >>> memory, using small reed relays. If one puts a magnet close >>> to one end, it will cause the reed to close. Move it back >>> some and it will hold until the field is too weak. >>> >... >> >> Dunno if they still sell them or not, but Radio Shack used to sell a pack of >> 20 reed switches for only a couple of bucks... >> >> > >Hmm... Wonder if it's possible to build a relay without a spring on the >switch. That is, you have to send current with one polarity to set the >switch to a 1 and reverse polarity to set a zero - sort of what core >memory does with rings... I suppose this could instead be done by >attaching a magnet to the switch, or using magnet as the thing inside >the switch body, or better yet maybe a relay with a ball with a set of >contacts as the switch and two magnets, one on each opposite side... >you'd energize one coil for a "1" and the other for a "0" > >Hmm, could even be done with a solenoid and use the mechanical part of >it to touch a wire for output. :-) Wouldn't really be a relay, but >pretty close. Telco stepping switches. I have a few. Also you can get small relays that are dual coil, one to set and one to reset. Widely used in automatic antenna tuners to select L and C as needed to resonate an antenna for most any frequency. The idea of a latching relay is once set no more power is needed. Allison Allison

18 years, 5 months

OT : CRT replacement

by cctech＠retro.co.za

Hi all Apologies for the off-topic, but I'm pretty sure someone here knows the answer to this one. A friend has a Motorola Communications Analyser model number R 2001 B. The CRT is blown. I don't even know if it's vector or raster, I'd suspect vector? Picture at http://www.econ2way.com/cgi-bin/service_monitor_display.cgi?site-images/Mot… Any idea where I can scrounge a replacement CRT, anyone? Thanks W

18 years, 5 months

Cold booting an Apple III ?

by jos.dreesen＠bluewin.ch

Is there a way to coldboot an apple III, if you do not have the SOS disks ? On the apple II you can do it via the serial interface and the Basic ROM, but the apple iii lacks these ROM's Jos DReesen

18 years, 5 months

Classic Computer Stuff Auction - More Items & Pictures Added

by ggama＠coakleytech.com

Do you still have the Trace 5 5 1/4" duplicator? Thanks, George

18 years, 5 months

PCKeybaord keytops

by cclist＠sydex.com

Last week, someone pointed me to Ergonomics Resources a source for decent PC keyboards, such as their version of the old Northgate unit. I voiced a concern about a pet peeve of mine--that the keytops would be the everyday surface-marked ones, rather than the old double-shot ones (which have legends that are almost impossible to wear away). Here's the response I received: "Thanks you for visiting our web site. The Stellar is in most ways like the Northgate keyboard you used many years ago. But they too have gone the way of Laser engraved key tops." "We do still have some (new in the box) Northgate Evolution Keyboards (split keyboards) that have the double injected keycaps if you're interested. " http://www.ergonomicsmadeeasy.com/index.asp?PageAction=VIEWPROD&ProdID =12 I guess I'll stick with my Model M. Cheers, Chuck

18 years, 5 months

IBM 4019 Laser Printer

by rtellason＠verizon.net

I have one of these, and it seems to be a real workhorse, as is evidenced by the status page it kicks out on powerup, which lists somewhere close to a quarter million pages having been printed out... That status page is a part of the problem. When I got it I was told that "a postscript board" was in it, and it indeed does seem to speak postscript just fine, but as long as I have that emulation enabled (as opposed to LJ or whatever, I think there were three or four choices altogether) it kicks out that page every single time you power it up. Is there any way to defeat this? Also, since I switched to using this LJ5 I acquired fairly recently, on pulling the paper out of the IBM it seems that a roller that sits on the top of the stack of paper is in the process of turning to goo, like those capstan rollers I see mentioned in here from time to time. Is there a rebuild kit or are replacement parts for this thing available out there anywhere? -- Member of the toughest, meanest, deadliest, most unrelenting -- and ablest -- form of life in this section of space, ?a critter that can be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters" - Information is more dangerous than cannon to a society ruled by lies. --James M Dakin

18 years, 5 months

PDP-11 comm stuff (and more) from a haul available

by henk.gooijen＠hotmail.com

Hi all,Last week I hired a truck to pick up a "few" things ...- H960 rack with PDP-11/45 and a Cypher 100 tape drive ("not working" sticker attached to the Cypher)- H960 rack with PDP-11/55 with 28k fast memory (according to the post-it attached to it)- H960 rack with TU45 ("seems complete" says the post-it)- H960 rack with TU16 (capstan rooler is goo)- H960 rack with communications stuff (see below)- two RK07 disk drives- RM03 disk drive- RM03P disk pack with diagnostics- two DECprinter I- DECwriter II- cabinet with SYSTIME SYSTAPE II unit (capstan also goo)- a few boxes, one contains a complete RH11-AB- RT-11 V5.4 SRC micro fiche (#1 - #86) in two envelopes complete with the Bill of Material!- complete RT-11 V4 manual set in blue binders- complete RT-11 V5 manual set in orange bindersNeedless to say that my wife was not so glad when I got home :-)I took pictures while unloading, and they will be on my website,probably a good moment to do that are the Xmas holidays ...I plan to get rid of most of this, and use parts to get otherunits in my collection restored into working order. The 11/45will go to Edward, the 11/55 is a great addition to my UNIBUSmachines collection.Most of the stuff will probably be too heavy to ship ...I disassembled the BA-11F with the comm stuff. The completepower harnass is for whom it wants/needs. I can take pictures.The BA11 contained two DR11-B 4-slot backplanes, populated withM7219, M208 (2x) M7821, M796, M205, M^11 (2x) M112, M113, M239and an M9680 DR11-B test connector board, power 'paddle' board,and connector board M9760 with two cables attached to it withon the other end one connector board (single height) M908?That single height connector board went into a small rack-mountunit with a 2-row backplane containing the folowing boards:M5950 (8x), M3020 (3x), M205 (5x), M111, M112, M306, M611 andone onit has M113 (3x) and the other unit has M113 (1x) andM1131 (2x). One unit was marked "RX", the other was marked "TX".On the side of the backplane is a label with this text:DIGITAL CSS P/N 2M-C121A S/N NU00001 DX40AB.The other unit has the same lable, but S/N is NU00002!Each unit has its own power supply, H716A.I elaborated a bit more about the comm stuff, because I reallydon't have a use for it, unless dismantling it. So, if somebodywants this (DR11-B or DX40 or everything), let me know.I have no idea what the things weigh, so neither do I know whatthe shipping costs would be. Free pick up in The Netherlands :-) allthough recovering some money from hiring the truck would be nice.I am also looking for two buttons of the TU45. They are damaged.It's the lower two on the control panel, "FILE PROT" and "1600BPI".thanks,Henk

18 years, 5 months

OT : CRT replacement

by dm561＠torfree.net

Date: Mon, 26 Nov 2007 11:43:08 +0200 From: Wouter <cctech at retro.co.za> Subject: OT : CRT replacement >A friend has a Motorola Communications Analyser model number R 2001 B. The >CRT is blown. >I don't even know if it's vector or raster, I'd suspect vector? >Picture at >http://www.econ2way.com/cgi-bin/service_monitor_display.cgi?site-images/Mot… >Any idea where I can scrounge a replacement CRT, anyone? >Thanks >W -------------------- If your friend is sure it's the CRT he/she must have had it apart; what's the number, size, etc.? m

18 years, 5 months

Documentation for the AT&T Sceptre Videotex terminal

by dm561＠torfree.net

-----------------Original Messages: Message: 29 Date: Wed, 21 Nov 2007 07:15:37 -0800 (PST) From: Cameron Kaiser <spectre at floodgap.com> Subject: Re: Documentation for the AT&T Sceptre Videotex terminal > But see, it HAS to be bad if Microsoft does it. One little key, and > the keyboard universe falls apart. I believe the objection was its placement, not the presence of a Windows-specific key. I've certainly had trouble adjusting to a Windows keyboard after being used to not having anything between Ctrl and Alt. Even Macs don't disturb that. Command is to the side of that group, not splitting it up. ------------------------------Reply: Well, yes, obviously the location is the issue, but it is still just another tedious MS-bash; I've got an APL keyboard here, and I think every "classic" terminal or computer keyboard I have here is different in some "improved" way but I don't hear complaints about that, or all the different PC layouts, especially the enter, backspace and \ keys. I find the WIN keys quite handy, and since they're control-type keys the location actually makes sense to me; just part of the DOS>WIN adjustment. Don't you also have trouble switching from a C64 to a Mac? m

18 years, 5 months

Teaching kids about computers...

by dm561＠torfree.net

--------------Original Messages: Date: Fri, 23 Nov 2007 12:58:17 -0500 From: "Roy J. Tellason" <rtellason at verizon.net> Subject: Re: Teaching kids about computers... On Thursday 22 November 2007 18:48, Chuck Guzis wrote: > Good point. There is the concept of "depth" of understanding. Many > people who regard themselves as programming professionals would be > lost without an operating system. Some would be lost without an > assembler. And, sad to say, some would be lost without some sort of > Java facility. This reminds me of folks I used to run into back in the day that considered themselves "programmers" -- in dbase! > For some, that's not sufficient. Understanding how a disk drive > works or what goes on over a TCP/IP connection is essential to them. Some of us actually enjoy that sort of thing and some just want to be able to use the end result, or maybe tweak it a bit. ------------Reply: Well, you've just insulted several thousand professional dBase programmers, myself included, with your elitist snobbery. I would guess that a competent dBase programmer would probably have the average small database program completed and delivered in the time it would take just to lay out, code and debug the necessary file- and screen-handling routines in most of the other comparable languages of the day, at least until you'd built up a decent and relevant library. Tools are developed to make a job easier and do it better; in my opinion taking advantage of those tools and doing things "the easy way" makes you more professional, not less. A programming professional's job is to deliver a product that meets the client's needs, is well documented and easily maintained, and is delivered on time and within budget. Knowing or caring about the arcane details of a disk drive or being able to program an OS-less computer in binary may matter if you're working on an embedded controller but it's pretty irrelevant if the project is a client accounting system for a large financial institution. What is important is good communication and organizational skills, the ability to conceptualize, proficiency in the use of whatever tools are appropriate to the job at hand, and enough humility to give the client what he/she really wants instead of what he/she *should have*, qualities often lacking in the "hacker" mentality. The same applies to the original topic: among the many replies suggesting how a child *should* learn about computers, I didn't see many suggestions that the child him/herself might be the best judge and perhaps the best approach might be to explore what his/her interests are (instead of what yours were), and provide whatever resources are appropriate and relevant to those interests. m

18 years, 5 months

Ebay item: Apple III

by oldcpu2＠rogerwilco.org

While I may have cut my teeth on an original Apple II (still in working condition!), but I think I'll pass on this. Looks like just the hardware...no doc or software. But for those that are interested... 150187810446 150187813983 - Jared (I have no connection with the seller).

18 years, 5 months

available Fw: vax equipment... (vax, teletype, tektronix, TI980 mini)

by jwest＠classiccmp.org

Here is a deal that I may want a part of, interested parties contact me off-list please.... Jay West > VAX 11/730 (with Bravo 3 CAD software) > The VAX also has a separate magnetic tape drive in another cabinet > A spare parts VAX > 2 spare hard drives > a couple teletype style terminals > 3 or 4 Tektronix terminals (with stylii for cad work) > a plotter > a couple paper tape punches > a large number of the large disc catridges > TI-980 w/ an ST-1 terminal

18 years, 5 months

Access to IOPAGE Registers using PDP-11 Opearting Systems

by bqt＠softjar.se

"Jerome H. Fine" <jhfinedp3k at compsys.to> skrev: > > >Johnny Billquist wrote: > >>> ons 2007-11-21 klockan 12:00 -0600 skrev "John A. Dundas III" >> dundas at caltech.edu>: >> >>> Jerome, >>> >>> I can speak for RSTS with some authority, RSX with somewhat less authority. >>> >>> At 9:17 PM -0500 11/20/07, Jerome H. Fine wrote: >>> >>> >>>> I doubt that RSX-11 or RSTS/E allow a user access to the IOPAGE >>>> even via PREVIOUS DATA space. Can anyone confirm this assumption? >>>> >>>> >>> Address space in the I/O page for RSTS jobs (processes) was not >>> directly available. The APRs are always controlled by the OS. It >>> MIGHT be possible for a privileged job to use PEEK/POKE SYS calls to >>> access the I/O page in the way you suggest but it would be >>> particularly difficult. >>> >>> >> I thought RSTS/E had some way of remapping the address space as well. >> Can't you remap parts of your memory to some shared region, for example? >> >> > Jerome Fine replies: > > I am replying to Johnny's response, but I had also read the other > replies as well. > Thank you all for your help. > > The first point is that using a PEEK/POKE SYSTEM (EMT? - RT-11 has such > a call) > is so high in overhead that it becomes almost useless. In fact, the key > point about the > use of the EMEM.DLL under RT-11 is the efficiency. While it is possible > to access > normal "emulated PDP-11" memory (using E11 on a 750 MHz Pentium III) in > about > 0.3 micro-seconds, it takes about 1.2 micro-seconds to reference an > IOPAGE address > in some sort of way - including the PSW or the EMEM.DLL values or about > 4 times > as long. Since this is a huge improvement over using a PEEK/POKE, it is > even worth > giving up 8192 bytes of address space to a dedicated APR (of the IOPAGE) > for that > purpose. True. From an efficiency point of view, using system calls to read/write memory is very inefficient. > On the other hand, with RT-11, it is possible and easy to set the > PREVIOUS DATA > space in the PSW to KERNEL even when VBGEXE is used - more to the point, > it is actually unnecessary since that is the default for a so-called > privileged job (which > all programs are by default). This allows the instruction: > Mov @#BaseReg,R0 ;Get the current value from PC memory > to be replaced by: > MTPD @#BaseReg ;Get the current value > Mov (SP)+,R0 ; from PC memory > with almost the same time for execution. It also avoids losing that > 8192 bytes for APR7 > being available just for the IOPAGE registers. That's not possible with OSes that maintain any kind of protection between processes, along with virtual memory. The PSW as such, is not possible to manipulate. If you could, you can also change your mode to kernel even though it's currently something else. Actually, you must be in kernel mode in order to modify the PSW with any other instructions than SEx and CLx. > Obviously, a SYSTEM request avoids all of the problems at a heavy cost > in overhead > estimated at between 50 and 500 times the above two examples. > > That was sort of what I was thinking about when I asked if there was an > "fast method > (only a few instructions)" to access an IOPAGE register. Well, in RSX, you have a rather high overhead to set up the mappping to the I/O page, unless it's already mapped in when the task starts. But from there on, there is no overhead at all. It's located somewhere in your 16-bit address space. (Note that you really don't have to map the I/O page at APR7 in RSX. You can get it mapped anywhere if you use the CRAW$/MAP$ or TKB options.) However, with normal privileged programs, the I/O page is always present at APR7 even if you don't do anything. >>> RSX had a bit more flexibility (opportunity) in this regard. I >>> believe you can set up a CRAW$ (create address window) directive in >>> either Macro or Fortran to achieve the desired result. >>> >> Yes with reservation. CRAW$ (create address window) is as a part of >> doing dynamic remapping of your address space. >> However, CRAW$ always required a named memory partition. You cannot >> create an address window to an arbitrary memory address. >> Also, the memory partitions have protections and ownership associated >> with them. >> >> On most systems, CRAW$ cannot get you access to the I/O page, simply >> because normally you don't have an address space and a partition >> associated with the I/O page. >> >> But if such a partition is created, then CRAW$, in combination with MAP$ >> would allow you to access the I/O page. >> >> The same thing can also be achieved even without CRAW$/MAP$, since you >> can specify mapping that your task should have already at task build >> time, with the COMMON and RESCOM options to TKB. >> >> > This seems to be the answer if it is allowed. Obviously it does require > giving up > that 8192 bytes the have APR7 mapped to user space. Correct. > There is also another option with E11 that I will make use of when I > have finished > with the HD(X).SYS device driver for RT-11. It turns out that if the > memory is > being accessed sequentially, the average time to reference a single 16 > bit value > in the file under: > MOUNT HD: FOOBAR.DSK > is actually less than the time to get/store a single value under > EMEM.DLL when as > few as 8 blocks (2048 words at a time) are being referenced. > Consequently, setting > up a small 4096 byte buffer and the associated code to handle to calls > to the HD: > device driver (all standard calls to .ReadF and .WritF in RT-11) is > actually more > efficient since after the values are in the buffer inside the program, > the values can > be referenced and modified at "emulated PDP-11" memory speeds. You mean that using a device driver, and a device that can access the "normal" memory instead is better. Well, I'm not surprised. What this essentially turns into, is that you're emulating DMA. > Of course, the above solution for sequential references does not work > when the > references are random or when references are at regular but very large > intervals > (thousands and even millions of successive values). For this latter > situation, it > may be possible to modify EMEM.DLL so that a single reference to the IOPAGE > register modifies all of the specified values (over a range of up to > many billions of > values). Can't comment much, since I don't know exactly what you're trying to do. But speedwise, if you really want something to act like fast disk, writing something that behaves like proper DMA is the best. You give the device a memory address, a length, and a destination address on the device, and let it process the data as fast as it can, without involving the PDP-11 after that point. > Of course, the result would no longer really be a PDP-11 except for the > controlling > code which would still be 99% of the required code since the EMEM.DLL > changes > are really quite trivial, yet consume 99% of the time to execute. In > case anyone > does not appreciate what I refer to, it is back to my other addiction - > sieving for > prime numbers. I realize that I should probably switch to native > Pentium code, > but is seems more of a challenge and much more fun to run as if a PDP-11 > is being > used with a few GB of memory somewhere out there that can be easily > fiddled with > as if there is a very fast additional CPU similar to those that used to > be available for > special math applications - anyone remember SKYMNK for FFTs? Hmm, are you just creating a sieve for primes? Ok, then you need large memory somehow. Several ways of doing that. For your specific needs, a simple device in the I/O-page with a command register, an address register and a data register would probably be just about the best. 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

18 years, 5 months

possibly OT: Styli

by chrism3667＠yahoo.com

did I spell styli correctly? Anyway does anyone know what's inside these things? That is the "radio frequency" type. I ordered a *bare* Stylistic 1000 and if I want to play etch_a_sketch on the screen I'm going to have to build one. No way I'm pay $40-75 for one seeing the unit cost $30! The Hacker Ethic says "how hard could it be to build my own stylus?". God made the whole Universe in 6 days, so... ____________________________________________________________________________________ Get easy, one-click access to your favorites. Make Yahoo! your homepage. http://www.yahoo.com/r/hs

18 years, 5 months

Programming skills (was: Teaching kids about

by dm561＠torfree.net

--------Original Message: Date: Sun, 25 Nov 2007 17:09:36 -0500 (EST) From: der Mouse <mouse at Rodents.Montreal.QC.CA> Subject: Re: Programming skills (was: Teaching kids about computers...) >> Although some people apparently disagree, dBase is not an application >> program; it's very similar to BASIC (and grew and matured just like >> BASIC did) but with fairly extensive file-handling and >> screen-handling capabilities. >How does that make it "not an application program"? >I suppose this really amounts to "just what do you understand an >`application program' to be?". Certainly my own understanding of the >term leaves room for something like dBase (or a Lisp engine, possibly >even with a text editor attached...or for a C compiler...or for that >matter for a BASIC engine). ---------Reply: You're absolutely correct of course; *any* piece of software written to make a computer do a certain task, including compilers, assemblers etc. is an "application program" and I thank you for pointing out that there is no distinction to be made between an accounting package or an MP3 player or the software controlling a car's engine and a computer "language" with defined words and symbols, rules of grammar and syntax etc. designed and used specifically to "program" some of those very applications (and which I mis-understood to be something distinct from an "application program")... And of course there's no categorical difference either between a hammer and saw and the chest of drawers one might build with them; both items intended for a specific "application." I've learned an important lesson (mainly: to as of right now try *very hard* to stop wasting time with these picayune "discussions") and I thank you again. m

18 years, 5 months

Commodore Watches (was Commodore PET first shipemnt in mid October 1977.

by dm561＠torfree.net

Date: Fri, 23 Nov 2007 17:12:44 -0500 (EST) From: bpope at wordstock.com (Bryan Pope) Subject: Re: Commodore PET first shipemnt in mid October 1977. >> Does anyone collect Commodore wristwatches? Do any working ones >> survive? >> >I know TPUG (http://www.tpug.ca) was selling a bunch of NOS C= >wristwatches a few years back... >Cheers, >Bryan --------- They're still (again?) available, although you'd have to be quick with your order; contact: Ben Kayfitz - downtownben at hotmail.com m

18 years, 5 months

classiccmp / cctalk / cctech (fwd)

by ard＠p850ug1.demon.co.uk

I have been asked to forward this to the list, since for some reaon the original poster is having problems doing so. -tony > The classiccmp moderation system is out of action. This mainly affects > the cctech list, but there are a few subscribers who post from an > address different to the one they are subscribed with and their postings > must be manually moderated through to cctalk. Sorry! > > Thanks, > -- > Lawrence Wilkinson lawrence at ljw.me.uk > Ph +44(0)1869-811059 http://www.ljw.me.uk > >

18 years, 5 months

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