test-drb

test-drb@ccmp.vtda.org

101090 discussions

by saltmabr＠boat.bt.com

Hello All, Can anyone help. I currently build my software on Intel Series III and NRM machines, problem is they are getting old and un-reliable. Does anyone know of a simulator which can be used to build ISIS environment software on a PC. I have tried ISIM, but that is limited to Series II (8085) applications. Regards Barry Saltmarsh

28 years, 4 months

Listserv?

by Zeus334＠aol.com

What is the e-mail address of the server for this list? I need to subscribe with a different address.

28 years, 4 months

C= PC Clone?

by gmast＠polymail.cpunix.calpoly.edu

I never knew Commodore made PC clones. There's one at the Goodwill. And a couple Aquarius keyboards. Never seen one of those either although I've heard about them plenty of times. GM

28 years, 4 months

Finds today

by jrkeys＠concentric.net

Well the last few days have slow again Holidays I guess. Picked up a Alpha Micro model AM1051-12 AM-410 SN 2517. It's a heavy unit and I have not powered it up yet. Anyone have any info on it. A TRS-80 RS232 Interface selector not tested. A AST-2000 Subsystem model MAC-200, anyone know what this unit is ? Four Mac IIci cases for parts only the guy let me have them for free. A Ultimate model 25 by ADDS with one aux port and EIA current loop port. That's it so far for the week. As far as prices no unit cost over $6.

28 years, 4 months

TRS-80 (Enrico, Bill, and anyone else that cares)

by SUPRDAVE＠aol.com

In a message dated 97-11-25 21:12:49 EST, Cord Coslor put forth: > This has got to be the most ridiculous thing I have ever heard: Cord <- vs -> Enrico argument deleted: I thought this was friendly discussion of old computer collecting, not alt.flame! put it in private, this is more off topic than complaining about the 10 year rule.

28 years, 4 months

MITS/Pertec/Sperry??

by rcini＠email.msn.com

Found the following on alt.folklore.computers: >>Pertec got bought by Sperry in the early '80s. So you'd probably >>want to check with Unisys (if anyone can still find the stuff >>after all those moves). Can anyone verify this? Maybe we should contact Unisys? Rich Cini/WUGNET <nospam_rcini(a)msn.com> (remove nospam_ to use) ClubWin! Charter Member (6) MCP Windows 95/Windows Networking ============================================

28 years, 4 months

TRS-80 (Enrico, Bill, and anyone else that cares)

by coslor＠pscosf.peru.edu

Enrico: This has got to be the most ridiculous thing I have ever heard. After being out of town for _Thanksgiving_ (I am a full-time college student and am now with family for a short break) I decided I might telnet back in and check my e-mail. Boy, am I glad I did. I wouldn't have wanted to miss you telling me that I was purposely trying to avoid you. You say in the second message from you, "I see that you are playing hard to get AGAIN." Yes, you're right, Enrico, I am scared of you (not really). Anyway, I will respond to both of your e-mails... one dated Nov 24 the other Nov 25. Boy, I certainly shouldn't have missed a day of checking my e-mail.... I'd hate to anger you for not checking the first e-mail from you immediately. In response to the e-mail dated Nov 24: you say you are unhappy with a transaction that took months to progress. You sent me an MSX (from UK), I sent you a TRS-80 Model 1. To tell you the truth, I am very unhappy with the transaction as well. First, it has been a huge pain in the rear-end >from the beginning. All I have heard from you is far-fetched reason for bitching... just another damn ploy to stir up a little trouble? Second, a point I have never even said to you before because I figured it might have happened in shipping, etc., is the fact the damn MSX doesn't even work. I'm not going to sue you though Enrico. Next, we have you saying you are unhappy with the transaction because the computer I sent isn't the one we agreed upon. Frankly, that's a big bunch of BS. You say in this letter that I told you and the list I would send one without the numeric keyboard. If I remember correctly you asked if I could send you the first TRS-80, this is true. Then in future discussion I asked you specifically what you wanted. You said you didn't even know what you wanted, just a model 1. I sent you the damn model 1. Enrico, you know something.... I don't even have a TRS-80 Model 1 without the numeric keyboard on the right hand side. Now tell me this, why the hell would I promise to ship one to you if _I_ didn't even have one?? Common sense (which you seem to lack quite a bit of) would tell you that I wouldn't do that. Next you _claim_ the computer is cracked or some damn thing like that. Well, I can promise that when I sent it is was just fine. No cracks, screws floating around nothing. And I can also promise the thing worked just great. You know how? Because I was using it up until the time I shipped it. You sure as hell didn't even send me something that was working. How do _I_ know... because if you knew it was working you would have powered it up and it still hadn't even had a power cable hooked to it. I put the correct voltage through it, I get power, but then it dies. Again, I won't sue you, Enrito. Then you say that I didn't send the power supply and the instructions. Then you say, quote, "(yes I know I told you that I was not interested in the power supply...I did send you the instructions.) Well, you answered your own darn complaint, Enrico. You didn't want the power supply. If you say, as you did, that we were swapping the exact same thing, you didn't send me a seperate power supply. :-) You did send me a xeroxed copy of the instructions, which I appreciate... I grant you that there. But, I honestly did not realise I was supposed to send you any manuals. I certainly can copy some off I guess. Or, you might even be able to check any number of web sites that contain much, much more information that any manual I would send you contains. Next, you talk about the fact that my machine to you was sent months after I said it did. It was, and I notified you the parcel was returned to me, at my expense. I even sent you an e-mail telling yuo about this, and that I even was going to re-use your box and packing as it would not be as quite a fit as what I had previously sent it in. Plus the original boxed was stamped and labeled throughout. I didn't think it'd cause a lawsuit. Then you say for me to just put everything right and it would be forgotten. Well, I don't have anything to put right... especially not at my expense. I will agree to send you POS MSX back to you, if you'll return my Model 1. How's that? LETTER # 2 - Nov. 25 Already replied to your comments about me playign ahrd to get. Then you say I should send you the model 1 with no numeric key-pad. You say they are hard to find in the UK, but worth 2 pennies here. Well, Enrico, I don't have one, so maybe someone else on this list will gladly ship you one of those. I'm sure they'd be happy to pick up where I refuse to continue to go. You say by me doing this, that any $$$ expense I incure will certainly be worth in terms of respectibility. You threaten me by saying that, "I will expose the whole lot in public on the list and in my site, and I will also write to the major Internet zines and news sites." Well guess what, Enrico, I personally don't care. As a matter of fact, I didn't even care enough to let your shitty side of the deal bother me. I guess I'm just not a hot-headed trouble maker looking for problems. Then you say, if necessary, you will ask a judge to put this right. Go for it, buddy. I didn't do anything wrong. If anyone did anything wrong, it was you. You didn;t even have a clue as to TRS-80s or what you wanted, and that seems to be the only thing I could have (if I even had one!) made different.... you would have had complete info. on what you wanted. Enrico, I can't even express how much this whole deal is a giant crock of $%!^. It is completely unrational statements by you that make this out to be something is not. I in no way intended to make this difficult, or trick you into sending you the 'wrong' machine or anything else. I know you didn't intend that either. But, should I just run around saying you had everything to do with the problems, etc., etc.? No. I don't beleive it was anyone else fault by _our own_. That's right, I don't think it was mine, and I don't think it was yours. What comes out of this will be two little kids fighting back and forth. Frankly, I have better things to do with my time. If you don't have better things to do, well, go ahead and slander my name wherever you want to. I don't care. No one has every had any problems with me, nor have I had with them. I sit back, read the newsgroups and listservs I get, trying to add to my collection and learn. I've already learned enough from doing this that I don't want to be part of these squables that go on for months at a time. So, I say, pay our own expenses, trade back, and it'll be over. Then you can find someone else who will ship you a Model 1 with _no_ numeric keyboard and I won't have to bother with you. When I first got into contact with you about a deal like this, it was just after a huge debate between you and others. "others" were saying it was hard to do these transactions over-seas. You responded on a whole thread of messages that those people that thought it was hard to do, were nuts, and made it into some type of international war. You know what, just because of that thread, I thought I would try transcting with you just to prove all my fellow Americans wrong. I had never done it before over-seas, and thought it would be a good learning experience. I guess I wasn't able to prove my fellow Americans wrong, but I did prove it to you. And I certainly proved it to myself. Love Always, Enrico. CORD G. COSLOR P.S. has anyone else out there ever thought I was 'playing hard to get?' Didn't think so. Oh, for all you judges, internet zines, newsgroups, listservs, web sites, executioners, and anyone else that's going to hate me because of this: please, please understand I am innocent. I don't want you all to hate me, and Mr. Judge, please don't make me pay the $18 to reimburse Enrico for silly reasons.. Please, please, please.... (the above is very synical, and like I said-- it's all set right if we just swap back. SOund simple enough? Didn't think so, Enrico... we need to make it _much_ more difficult.) :-) :-) <-- those are smiley faces. Ever smile? If not, Enrico, think about it all this logically.... trust me, it will make you smile. //*=====================================================================++ || Cord G. Coslor P.O. Box 308 - 1300 3rd St. Apt "M1" -- Peru, NE || || (402) 872- 3272 coslor(a)bobcat.peru.edu 68421-0308 || || Classic computer software and hardware collector || || Autograph collector || ++=====================================================================*//

28 years, 4 months

Now it's a RSTS problem.

by dseagrav＠bsdserver.tek-star.net

Now INIT says the CSR for the booted device (The UDA50? That's what it's booted from...) is non-standard, and RU0: (WHatever that is) is not interrupting and is disabled. RU0: is not in my manual. Neither is anything about the UDA50. So, I'm stuck again! Anyway, I'm gonna go try fitting this into the racks... Anyone got any ideas before I go try figuring it out on my own?

28 years, 4 months

FW: Someone help this fellow?

by allisonp＠world.std.com

<From: kyrrin2(a)wizards.net <Subject: DEC 1 computer (circ. 1982) <problem is a disk errors when he tries to boot. I presume (as I have <yet to inspect the machine myself) the trouble to be with either the <boot disk drive (8" Shugart floppy drive) or the system disk. The <problem could be as simple as a dirty r/w head or a worn felt pad that <presses disk against the r/w head or as bad as a fried system disk. <Though as a tech I have worked on several machines of this era, I am <at a disadvantage in this case seeing that I have never seen a DEC 1 <running properly or at all for that matter. The ONLY possibility is a DEC VT180 as that is the only DEC hardware I know with shugart floppy drives (sa400l 5.25" single sided). DEC used RX01/02/03/6 which was calcomp drives. DEC-1???? need more info. could he mean a decmate-I Still used RX01/2. <a) Spare parts or a PM kit for a Shugart 8" floppy drive <b) Someone who has spare system or boot disk for a DEC 1 that they < might be willing to part with <c) someone who has a clue or any usefull insight! A better description of the system and a better description of the problem would make easier to suggest solutions. Allison

28 years, 4 months

FW: Someone help this fellow?

by kyrrin2＠wizards.net

Can anyone help this fellow out? I've never even heard of a "DEC 1" (unless he means a MicroVAX 1?) Forwarded message follows. Please respond directly to the author. Thanks! -=-=- <snip> -=-=- Xref: xyzzy comp.sys.dec:18347 Path: xyzzy!uunet!not-for-mail From: mrogers(a)capecod.net (mr) Newsgroups: comp.sys.dec Subject: DEC 1 computer (circ. 1982) Date: Tue, 25 Nov 1997 08:21:08 GMT Lines: 20 Message-ID: <347a81fe.29676018(a)newshost.capecod.net> NNTP-Posting-Host: ost55.capecod.net X-Newsreader: Forte Free Agent 1.11/32.235 Anyone out there ever see one of these beasties? A freind of mine has ask me to resusitate his beloved dinosuar, so here it goes. The problem is a disk errors when he tries to boot. I presume (as I have yet to inspect the machine myself) the trouble to be with either the boot disk drive (8" Shugart floppy drive) or the system disk. The problem could be as simple as a dirty r/w head or a worn felt pad that presses disk against the r/w head or as bad as a fried system disk. Though as a tech I have worked on several machines of this era, I am at a disadvantage in this case seeing that I have never seen a DEC 1 running properly or at all for that matter. So what I'm looking for is: a) Spare parts or a PM kit for a Shugart 8" floppy drive b) Someone who has spare system or boot disk for a DEC 1 that they might be willing to part with c) someone who has a clue or any usefull insight! Thanx for reading.

28 years, 4 months

RD51 format parameters?

by jimw＠agora.rdrop.com

I should probably know this by now, or be able to figure it out, but its been one of those weeks to far, with no signs of improvement... I need to format up an ST-212 drive as an RD51 (don't ask, I just need to) and can not for the life of me remember (or find my notes) the parameters to feed the formatter on my VS2000 to format this thing. Anyone have these parameters at hand? (Ok... I'm trying to load Micro-RSTS on one of my machines, and the distribution disk set installer demands an RD51 as the system drive) Thanks! -jim --- jimw(a)agora.rdrop.com The Computer Garage - http://www.rdrop.com/~jimw Computer Garage Fax - (503) 646-0174

28 years, 4 months

Rubbery Bits Gone Gooey

by fmc＠reanimators.org

Lately a friend has been trying to copy a tape for an HP 2645 terminal. Thus far he has discovered a problem with tape drives in two terminals. His description of the problem is that, when used, the motor capstan in the tape drive "melts". In one case he has not been able to get all the ex-capstan goo off of the belt capstan in the cartridge; fortunately that was a blank tape. My first thought was, hmm, this sounds like the problem the calculator folks have with the rubbery wheels that go gooey. I have one of these terminals too, but it's a bit buried in storage and I haven't got it out yet. (In fact, the tape contains games and he is trying to copy it because I expressed interest...of course, now I am thinking that when I dig the terminal out I need to open it up and check the capstans before I go and jam a tape in.) Instead I found the May 1976 issue of the HP Journal, which was smaller, lighter, closer to the front, and does a pretty good job of demonstrating how proud HP was of having fit tape drives to HP 264x terminals. What have I found out? The motor capstan has an aluminum core with an elastomer coating that is ground to the right size during manufacture. Said elastomer was chosen for quick recovery from the dent that forms in it when the loaded tape isn't moving (as the capstan is held against the tape cartridge's belt capstan). So now I guess I have two questions. One is just what do the calculator folks do about rubbery wheels gone gooey? And the other is, can I do something like that for these drives? Given that the object of this capstan is to press against and drive something less flexible than a magnetic card (the belt capstan in a DC100 tape cartridge) I'm not sure the same sort of material would work. And an observation: the HP 9815A desktop calculator I have sitting here seems to use a similar drive (at least the capstan looks similar when I peer in the slot), and I think the HP 85 does too. -Frank McConnell

28 years, 4 months

PET Finds

by foxnhare＠goldrush.com

From: Grant Zozman <gzozman(a)escape.ca> Subject: Re: Commodore PET finds. >Scott Walde wrote: >> >> I also got 4 'MSD Super Disk Drive' model SD-1. These look similar in >> design to the external TRS-80 drives (except they're cream coloured). >> They have two 6-pin DIN plugs and an IEEE-488(?) plug. Are these what I >> think they are? (Drives that will work on the VIC-20/C-64 and PETs) I >> don't have any 6pin cables to try these on a VIC. I haven't tried them on >> a PET yet, either. Any idea what format these would be? (2040, 8050?) >The MSD drive will definitely work with a C-64. By extension, I belive >this means it will also work with the VIC-20. Not sure about PET >compatibility, though I believe the IEEE-488 interface was provided for >PET's. And they will work on the PET too! Yes, that is an IEEE-488 interface. and I have had mine (an SD-2, pretty cool drive!) hooked to my PET (before I sold it). and it provides you with 1541/4040 compatibility. Though not EXACT, as that would have violated Commodore's copyrights. I have read you can get JiffyDOS for various 3rd party drives and I think the MSD was one of them. Larry Anderson -- -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Visit our web page at: http://www.goldrush.com/~foxnhare/ Call our BBS (Silicon Realms BBS 300-2400 baud) at: (209) 754-1363 -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-

28 years, 4 months

Intro msg: Teraks, emulators, reviving cassette data

by allisonp＠world.std.com

<Well there were -10s and then there were -10s. Ours consisted of 25 19" <style rack cupboards next to each other (so it was about 40 odd feet in <length). There were three racks for the CPU, four for memory (we had 256KW That was a big ten! But compare it to a 9020(360/60) used by the FAA. Or for that fact some of the -10s used by compuserve, they had some really huge ones and not just a few. The biggest one inside DEC was the MARKET cluster, yep four -10s clustered sharing the same disk field. But a lot of 10s were small 128kw, swapdrum, maybe four RP04s and an 8I or 8E for IO control. The whole mess was two rows 24ft long. The CPU box alone for the 360 next door was 4x the size of the KA10 cpu. that seems big but a PDP-11 of that era would be 3-4 standard racks plus drives. <There were plans for the so called Jupiter system which was due to ship Jupiter was due to ship around '84 the 780 was sold in '78! The story is this (I worked in the mill at the time) Jupiter was required to perform at 4x the last System10/20. The best the design team could accomplish was 2x (subtantial enough but below design goal). It was also competing for resources(money) to design and build the 86xx (nautalus). What wasn't known was the cutomer base was hungry for even 2x increase. The day it was canceled was a very dark one for the engineering groups. <Sitting at home I have all the necessary bits to put together an Apple II <system to run UCSD Pascal. All I need is the time and the software (the on <bit I don't have). The reason for wanting this is Carl Helmers Byte articl <so many years ago describing such a system - for me the first microcompute <that was usable rather than a "toy" to play with. The appleII was more useful than most of the other non s100 systems like trs-80s which didn't have solid hardware at that time(EI timing problems). if you had a solid trs80 you could run UCSD psystem. I was running Psystem on a Northstar horizon with three drives and it was a useful system. Allison

28 years, 4 months

Intro msg: Teraks, emulators, reviving cassette data

by jfoust＠threedee.com

Why, I thought I'd get a few replies about my Terak computer collection, as described in my intro message on 11/18. Anyone out there have any experience with these? - John www.threedee.com/jcm

28 years, 4 months

Intro msg: Teraks, emulators, reviving cassette data

by jrkeys＠concentric.net

found a small written piece talking about the Terak 8510 with a LSI-11 processor, 20k words of 16 bit memory, 256k floppy drive, came out in January of 1977, cost at the time of over $5000, had RS232 and 20mA current loop serial interfaces. Software was Basic and Fortran. Hope this helps Keep computing - John At 10:31 AM 11/24/97 -0600, you wrote: > >Why, I thought I'd get a few replies about my Terak computer >collection, as described in my intro message on 11/18. >Anyone out there have any experience with these? > >- John >www.threedee.com/jcm > > >

28 years, 4 months

PROGRESS! It booted!

by dseagrav＠bsdserver.tek-star.net

I was fiddling and I pulled the NPG from the Unibus ribbon cable and the machine will boot now! But when I try starting RSTS timesharing (START command to the bootloader [Is that INIT?]) it lists devices it disables and hangs there. I can see an LED go high on the 2nd UDA board (The one that doesn't connect to the drives), stay high for a second, then go lo, strobe, and repeat. The READY lamp on the RA81 has died, so I can't really tell what's happening... I'll go RTFM tonight, but if anyone knows for sure what's happening, it'd be nice to know!

28 years, 4 months

Talk Of Building A Computer...

by SUPRDAVE＠aol.com

In a message dated 97-11-21 06:21:27 EST, HOTZE put forth: > PS- I've been looking for this for months. Does anyone know where I can find > the latest version of Elisa (Or another good AI) on the net? Elsewhere? elisa? that program that asks you the same open ended question? i may have a similar program if there really is an interest. david

28 years, 4 months

[PDP-11/44]: OK, this has become an emergency situation!

by dseagrav＠bsdserver.tek-star.net

Here's the deal: Our landlord (at work) showed up. He was not happy with the '44, at all. It is currently in an unused room. (I have no other place to put it!) It looks quite ugly, as it's not working and all over the place. I cleaned up the best I can, but it's not enough. Since nor my business nor me can afford the spare room, I have been given orders to make it look nice. I have 3 days. After which, if the room does not meet his standards, he'll take the computer and feed it to the scrap man. I can't afford the room, I'm broke. And I can't move it anywhere else. Basically, I have 3 days to get everything back in the racks. And working if possible. Or else, whatever I can't fit in my car is property of the building owner, and then the scrap metal man. If I can make it run, I can put it in the main office (maybe). The uPDPs and such have to find another place to stay... One'll end up at my house, and the others probably in storage. I have things almost ready. The 2 BA11s power on, but there appears to be no bus continuity. The arragement has the CPU and RAM in the master BA11, and the UDA50 in the other. No DZs or anyhting yet. The lights on the UDA stobe normally, but it refuses to boot. It is in an NPG slot (I looked, the CA1 wire is cut), like it was originally. Just those MASSBUS backplanes are gone. I have NPGs in every available slot. There is one terminator, at the end of the bus. WHat am I doing wrong?

28 years, 4 months

CGA & clock speeds

by allisonp＠world.std.com

<booted but did not give a display. I could tell it was working by <entering <DOS commands. I tried then at 5.33 MHz. It booted & ran OK (as far as <and found that the CGA card depends on the 14.31818 oscilator to run <properly. <Since the processor seemed to be running OK at 8 MHz, what I want to do Simple make sure you supply 14.31818 to the ISA bus from a seperate oscillator (or put it on the CGA card and bypass the buss connection). The problem is that much of the machine is timed off that clock. it is generated either using then 8284A clock generator or or a TTL oscillator can. The 8088 is driven off the 8284A (it supplies the correct 33% duty cycle closk) so it could be done as two seperate sources. There were "upgrades" that did exactly that yo yeild turbo systems. Allison

28 years, 4 months

IBM s/36

by Philip.Belben＠powertech.co.uk

> I=B4m afraid this computer is off-topic (dated 1988). Sorry.=20 Never mind. There were system/36 machines around in 1985 and even earlier... > An IBM 5363-I has recently been given to me, but I don=B4t know anything > at all about its internal architecture or capabilities. I only own the > Central Unit; no cables, no floppies, no tapes, no manuals, no > terminals. I don't know the system/36 awfully well - I worked more on system/34s - how big is this physically? The 5362 was desk-side, the 5364 desktop (the same box as the PC/AT), but I don't know the 5363 (probably after my time if it's 1988). > * It has two 15-pin sub-d connectors in one expansion card. They seem to > be for attaching two serial terminals (syncronous? type 5250?) Dunno. Probably not 5250 - these hang in chains (pun intended) off the twinax ports. > * In another expansion board it has a 9-pin sub-d connector. > * There are too four twin-axial connectors. Four? Quite a sizeable system, then. > Can anybody help me on this subject? > > Thanks in advance. Just my tuppence worth! I'd guess you've got a fairly powerful (by 1980s standards) machine. Philip.

28 years, 4 months

Talk Of Building A Computer...

by photze＠batelco.com.bh

Hello... some time ago, there was talk of building a computer, and now I think that I've got a (bad, possibly) idea. In the earlier half of this century, transistors weren't avaible... vaccum tubes... huge ones, but now, the transistor has made small ones possible. My point: If we were to take a tubed design, and re-build it with transistors, we could probably make it a decent size. So, what da ya think? Tim D. Hotze

28 years, 4 months

Case designs (was: New Definiton REQUIRED)

by manney＠nwohio.com

>Some people (esp. on this list) may not realize it, but there are actually >hordes of people out there who go their entire lives without ever owning a >single screwdriver. Which is why I've got two in/on my laptop case, several >in my laptop "kit", and a swiss army knife with a flat sd, phillips sd, >pliers, and (8^) corkscrew. I treated myself to a Leatherman folding tool 6 months ago. It's got a very well-made #1/#2 combination phillips, plus a very nice pliers & other stuff, even a tiny screwdriver (screweler's jewdriver, as my spoonerist father would have said). $40 at Wal-Mart, and the best tool purchase I've _ever_ made. It hangs on my belt all the time -- even take it to church. I'm always ready to fix. Buy one. manney(a)nwohio.com Murphy was an optimist!

28 years, 4 months

TRS-80 Model I

by foxvideo＠wincom.net

At 05:13 PM 11/23/97 +0000, you wrote: > > >On Sun, 23 Nov 1997, Charles E. Fox wrote: Thanks, Tony, I will give it a try. Charlie > >> >> On a TRS-80 Model I, no expansion unit, I am getting the left half of the >> screen filled with graphics and the right half with scrambled text. Does >> anyone have a suggestion of where I should start looking for the solution >> to this problem? > >Well, it's been 5 years since I read the Model 1 technical reference >manual, but I can still remember some bits of it (I hope).. > >Start by opening the case, laying the 2 boards out component-side up, and >connecting power and video. If you want step-by-step instructions on how >to do that, please ask. Turn on the machine. Is it fixed? If so, suspect a >solder-ball short (these were quite common one some batches, I believe) or >a problem in the keyboard cable, which carries the Z80 bus. In fact, >checking that keyboard cable for continuity (with the machine off, of >course) wouldn't be a bad idea. > >OK, still not fixed? Check the PSU. The 0V line is the -ve side of the >largest capacitor on the board, and all the supply rails go to the DRAM >chips (-5V on pin 1, +12V on pin 8, +5v on pin 9). > >Now switch off and pull the shunt block (it looks like an IC, but has >metal shorting bars on it only). That disables all the DRAMs. Turn on >again. On a Level1 machine (and I believe a level 2 machine, but my manual >isn't that clear) you'll get a 32*16 display of colons. If that occurs, >then you've probably got RAM or RAM addressing problems. > >Switch off again, and pull the ROMs (or on a level 2 machine, pull the 24 >pin ribbon cable from the ROM socket). Turn on again. The Z80 data bus is >pulled high, so the machine executes continual RST38 instructions and >fills all of the memory with 39 00 (the return address, of course). The >display will fill with alternate '@' and '9' symbols, in 64*16 mode. If >that works, then you have ROM trouble, I think. > >If you still don't get the right display, reseat the Z80, and then use a >scope/logic probe/LogicDart to find out (a) what the Z80 is doing, (b) >what the buses are doing and (c) what the video controller is doing. > > >> >> Thanks >> Charlie Fox >> >> > >-tony > > >

28 years, 4 months

CGA & clock speeds

by defaultuser＠mail.mankato.msus.edu

Hello, I hope this mail goes to the right place as I'm not on the list; here goes: I am messing about with an 8088-based clone to see what I can do with it for cheap thrills & a good learning experience. So far, I have installed a V20 chip which decreased processing time by about 7%. I then tried to clock it at 10 MHz (the rating of the chip), but this failed to produce any results (the 'puter did not boot.) I tried at 8MHz, and the computer booted but did not give a display. I could tell it was working by entering DOS commands. I tried then at 5.33 MHz. It booted & ran OK (as far as I could tell), but the display was all messed up. I then did some research and found that the CGA card depends on the 14.31818 oscilator to run properly. Since the processor seemed to be running OK at 8 MHz, what I want to do is find a way to send a proper clock signal to the CGA card while clocking the main board at 8MHz. Or will changing to a different monitor (like VGA) make the clock speed irrelevant? Is CGA the only clock-dependant display type? Thanks in advance, Dave

28 years, 4 months

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