test-drb

test-drb@ccmp.vtda.org

101090 discussions

by allisonp＠world.std.com

<These I/O ports are all 8 bit, right? < <Now, an S100 frontpanel would have 16 toggle switches (at least - to <load a memory address). So why can't you either You could they didn't and they board was chockfull of crap and a little more would have made a mess of it. In 1974 the altair was an "ok" design at best. It was one set of engineers vision and at that point their best shot. They did it that way. Allison

28 years, 3 months

front panels

by allisonp＠world.std.com

<Was the latter really considered a problem in those days? Or was it <just that as a result it wasn't real useful to have the front panel do <that? (Or was it just the additional cost of having the front panel <do that?) Fancy way is, cost benefit ratio. It cost a lot! Another was, it's easier to not do that. Actually it was rare I needed the ability. Allison

28 years, 3 months

front panels

by allisonp＠world.std.com

<But what does an instruction do? It just generates bus cycles, right? <The bus doesn't care whether those cycles come from the CPU or something <else (unless there's bus mastering and arbitration, which I doubt). In theory your correct. <The difference between generating a memory cycle and and I/O cycle on an <Intel CPU is simply a matter of clocking a different value onto the <"control bus" (which might be a multiplexed bus, I don't know the 8080 <that well). Reducing that to practice and at a low cost on S100 bus with an 8080 is a different matter. To understand that you need to know both as S100 was not a bidirectional data bus(seperate data in and data out paths) and all the bus control signals were RAW 8080 status/controls making it a royal pain to do DMA on the bus. To make a point to do a memory write on the bus you have to output SWO/, PWR/, MWRITE, SMEMR, SOUT, SINP, PDBIN and all of them must be in the correct state (some are active high!). S100 was a poorly designed bus in that respect. I may add that Altair 8800(a) and Imsai were not bus masters, they were more CPU control. The best way to descrive this is if the CPU was Not there the front panel was an ornament. Allison

28 years, 3 months

Photo of Smithsonian microcomputer exhibit

by higginbo＠netpath.net

At 06:34 PM 2/24/98 PST, you wrote: >A friend of mine was recently in D.C. and took this >photo of the Microcomputer exhibit in the Smithsonian >Museum. I recognize the Altair and the Sol but what >is the Apple prototype sitting on the table? Here is the >link to the photo... Looks like an Apple I to me, but then again I've never seen an actual model in person.

28 years, 3 months

hamfest finds

by rigdonj＠intellistar.net

Hi, I just got back from a hamfest. Found two brand new in the box full height Tandon floppy drives for the IBM PC. Rich, do you want one? I also bought two AT&T 3B1 computers without keyboards or monitors. Does anyone know if the keyboard and monitor from a AT&T 6300 will work on them? Or where I can find a monitor and keyboard? Also need any advice about how to get these up and running. What are all the ports for? etc Joe

28 years, 3 months

HP2100

by MAKelller＠swbell.net

Gentlemen, If this computer is still available, we still use them to run a couple of our milling machines. MAKeller Northrop Grumman Aerospace

28 years, 3 months

North Star Horizon

by jthiemann＠castleton.com

While I don't have experience with the Horizon, I think it is similar (software-wise) to the Advantage (though the Advantage is NOT S100). I have some software, some for CP/M and some for the NS-DOS. Note that the floppy disks are hard sectored, impossible to find nowadays and just as hard to read/write on anything else... (AFAIK - if someone has a program to do this please speak up!) Joachim (I usually sign "Joe" but I think that would cause confusion...) > Joe, > > I don't know if software is available but will ask. Does the NS > horizon use a S-100 bus? I was told the unit I'm (hopefully) about to > > acquire has an internal 10MB hard drive. i'm going to go eyeball the > unit within the next few days. > > Marty > > > ______________________________ Reply Separator > _________________________________ > Subject: Re: North Star Horizon > Author: classiccmp(a)u.washington.edu at internet > Date: 2/24/98 1:00 PM > > > Marty, > > I have some manuals for the NS Horizon; disk controller, DOS, > BASIC, > Pascal. I'm looking for the software. > > Joe > > At 12:36 PM 2/24/98 -0500, you wrote: > > Does anybody have any information on a North Star Horizon? I may be > > > acquiring one of these soon but don't know much about it except > that > > it has wooden side panels and used to support a half-dozen > terminals. > > Is it a S-100 bus? > > > > Thanks for any help- > > > > Marty Mintzell > > > > > > > ------ Message Header Follows ------ > Received: from lists3.u.washington.edu by smtp.itgonline.com > (PostalUnion/SMTP(tm) v2.1.9i(b5) for Windows NT(tm)) > id AA-1998Feb24.130031.1767.28490; Tue, 24 Feb 1998 13:00:34 -0500 > Received: from host (lists.u.washington.edu [140.142.56.13]) > by lists3.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.05) with > SMTP > id JAA14977; Tue, 24 Feb 1998 09:53:52 -0800 > Received: from mxu2.u.washington.edu (mxu2.u.washington.edu > [140.142.32.9]) > by lists.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.05) with > ESMTP > id JAA53378 for <classiccmp(a)lists.u.washington.edu>; Tue, 24 Feb > 1998 > 09:53:44 -0800 > Received: from star1.intellistar.net (star1.intellistar.net > [206.105.64.2]) > by mxu2.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.09) with > ESMTP > id JAA05718 for <classiccmp(a)u.washington.edu>; Tue, 24 Feb 1998 > 09:53:43 > > -0800 > Received: from lizard ([206.105.68.41]) by star1.intellistar.net > (Post.Office MTA v3.1 release PO203a ID# 0-41809U2500L250S0) > with SMTP id AAA22727 for <classiccmp(a)u.washington.edu>; > Tue, 24 Feb 1998 12:53:39 -0500 > Message-Id: <3.0.1.16.19980224125410.0877b306(a)intellistar.net> > Date: Tue, 24 Feb 1998 12:54:10 > Reply-To: classiccmp(a)u.washington.edu > Sender: CLASSICCMP-owner(a)u.washington.edu > Precedence: bulk > From: Joe <rigdonj(a)intellistar.net> > To: "Discussion re-collecting of classic computers" > <classiccmp(a)u.washington.edu> > Subject: Re: North Star Horizon > In-Reply-To: <1998Feb24.123503.1767.83436(a)smtp.itgonline.com> > Mime-Version: 1.0 > Content-Type: text/plain; charset="us-ascii" > X-Sender: rigdonj(a)intellistar.net > X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN

28 years, 3 months

North Star Horizon

by peacock＠simconv.com

Joe wrote about a Northstar Horizon: > I think it uses the S-100 bus. According to their manual, North Star >used the same disk controller in the Horizon that they sold for the S-100 >systems. I have a NS S-100 controller. They are the same electricaly and >software wise but maybe physically different. I did some software work on a Horizon many years ago. As I recall, it had two full height 5.25" bays, a good sized power supply behind the bays (on the right side) and a shorty S-100 card cage on the left, 8 card slots? But the NS motherboard also had some logic on the motherboard, at the rear. I believe there were one or two 8251 serial ports, a baud rate generator, maybe a parallel port or interrupt controller (look for an Intel 8214 or a 28-pin AMD IC)?

28 years, 3 months

front panels

by peacock＠simconv.com

Tony wrote: >> >> >> <But surely this is a limitation of the front panel not the processor. >> <I/O bus cycles can (easily) be generated from an appropriately designed >> <front panel. >> >> Processor. The 8080 CPU does I/O To/From the accumulator which is > >I beg to differ. > >All you have to do is to put the CPU into a wait state, tri-state the >bus buffers and directly drive the address, data and control lines from >hardware on the frontpanel controller. You can access memory or I/O ports >that way. > In other words, make the front panel do a DMA access, either to memory or an I/O port? That way it doesn't affect the CPU state at all, except the CPU has to be running in order to handle the DMA grant.

28 years, 3 months

KNOXM5 RSTS Rides Again!

by DSEAGRAV＠toad.xkl.com

I finally got the **** thing to boot every time without falling over sideways! This is a step! The only problem is, it's still single-user - I still can't get a DZ-11 to work. I don't think I ever will - I was told you have to kill a 12-pack to get one to work, and I'm not old enough to buy beer. :) Anyway, I found an interesting goody in the spare 44 - It's a hex-height board I recognised from the VAX 750 manual I have. It has 2 50-pin cables going off to a 16-port EIA distribution panel. It appears to be a DMA peripheral, it has CA1 and CB1 going off into logic, so I made a DMA slot for it after the UDA50 in the 2nd BA-11. So, I bring up RSTS - And here's the result: Option: HARDWR LIST Name Address Vector Comments TT0: 177560 060 RU0: 172150 310 Units: 0(RA81) KL0: 176510 300 <<< What is that? KW11L 177546 100 SR 177570 Volatile DR 177570 Hertz = 60. Other: FPU, 22-Bit Addressing, Data Space, Cache -------------------- AFTER THE INSERTION OF THE MODULE ------------------- Option: HARDWR LIST Name Address Vector Comments TT0: 177560 060 RU0: 172510 310 Units: 0(RA81) KL0: 176510 300 DM0: 170500 440 DH0 KW11L 177546 100 SR 177570 Volatile DR 177570 Herts = 60. Other: FPU, 22-Bit Addressing, Data Space, Cache ----------------------------- But when I say START: KB9:KB24 disabled - no DH0: controller Does that mean it's broken, or is the Monitor need rebuilt? Oh, and Tim: The tape drives appear to handle 1600 BPI, but the controllers don't. I'm gonna dig out my Emulex stuff and see if any of them will handle this tape. And wasn't DM0: a disk controller? Am I supposed to reset the CSRs to this? -------

28 years, 3 months

Fire in the Valley

by mallison＠konnections.com

I just lucked onto a second copy of "Fire in the Valley" Anyone _NEED_ this? -Mike

28 years, 3 months

old SCSI controller

by peacock＠simconv.com

-John Rollins typed: > >>OK, does anyone know what this card came from? Anyone know what uses and 86 >>pin bus? This is from vague memory, but if the card is roughly the same size as an S-100 card (5 x 10 inches) and has an 86 pin bus connector, I think it might be an old Motorola bus. I don't remember what they called it, never used Motorola development systems, but it was Motorola's answer to Intel's Multibus.

28 years, 3 months

North Star Horizon

by Marty＠itgonline.com

Joe, I don't know if software is available but will ask. Does the NS horizon use a S-100 bus? I was told the unit I'm (hopefully) about to acquire has an internal 10MB hard drive. i'm going to go eyeball the unit within the next few days. Marty ______________________________ Reply Separator _________________________________ Subject: Re: North Star Horizon Author: classiccmp(a)u.washington.edu at internet Date: 2/24/98 1:00 PM Marty, I have some manuals for the NS Horizon; disk controller, DOS, BASIC, Pascal. I'm looking for the software. Joe At 12:36 PM 2/24/98 -0500, you wrote: > Does anybody have any information on a North Star Horizon? I may be > acquiring one of these soon but don't know much about it except that > it has wooden side panels and used to support a half-dozen terminals. > Is it a S-100 bus? > > Thanks for any help- > > Marty Mintzell > > ------ Message Header Follows ------ Received: from lists3.u.washington.edu by smtp.itgonline.com (PostalUnion/SMTP(tm) v2.1.9i(b5) for Windows NT(tm)) id AA-1998Feb24.130031.1767.28490; Tue, 24 Feb 1998 13:00:34 -0500 Received: from host (lists.u.washington.edu [140.142.56.13]) by lists3.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.05) with SMTP id JAA14977; Tue, 24 Feb 1998 09:53:52 -0800 Received: from mxu2.u.washington.edu (mxu2.u.washington.edu [140.142.32.9]) by lists.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.05) with ESMTP id JAA53378 for <classiccmp(a)lists.u.washington.edu>; Tue, 24 Feb 1998 09:53:44 -0800 Received: from star1.intellistar.net (star1.intellistar.net [206.105.64.2]) by mxu2.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.09) with ESMTP id JAA05718 for <classiccmp(a)u.washington.edu>; Tue, 24 Feb 1998 09:53:43 -0800 Received: from lizard ([206.105.68.41]) by star1.intellistar.net (Post.Office MTA v3.1 release PO203a ID# 0-41809U2500L250S0) with SMTP id AAA22727 for <classiccmp(a)u.washington.edu>; Tue, 24 Feb 1998 12:53:39 -0500 Message-Id: <3.0.1.16.19980224125410.0877b306(a)intellistar.net> Date: Tue, 24 Feb 1998 12:54:10 Reply-To: classiccmp(a)u.washington.edu Sender: CLASSICCMP-owner(a)u.washington.edu Precedence: bulk From: Joe <rigdonj(a)intellistar.net> To: "Discussion re-collecting of classic computers" <classiccmp(a)u.washington.edu> Subject: Re: North Star Horizon In-Reply-To: <1998Feb24.123503.1767.83436(a)smtp.itgonline.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Sender: rigdonj(a)intellistar.net X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN

28 years, 3 months

North Star Horizon

by Marty＠itgonline.com

Joe, Thanks for the information. I'm located in northern Virginia just outside Washington, D.C. Marty ______________________________ Reply Separator _________________________________ Subject: Re: Re[2]: North Star Horizon Author: classiccmp(a)u.washington.edu at internet Date: 2/24/98 5:07 PM Marty, I think it uses the S-100 bus. According to their manual, North Star used the same disk controller in the Horizon that they sold for the S-100 systems. I have a NS S-100 controller. They are the same electricaly and software wise but maybe physically different. Sounds like a neat system, I've never heard of one having a hard drive. Keep me posted. BTW where are you? I'm in Orlando, Florida. Joe At 01:10 PM 2/24/98 -0500, you wrote: > Joe, > > I don't know if software is available but will ask. Does the NS > horizon use a S-100 bus? I was told the unit I'm (hopefully) about to > acquire has an internal 10MB hard drive. i'm going to go eyeball the > unit within the next few days. > > Marty > > >______________________________ Reply Separator >_________________________________ >Subject: Re: North Star Horizon >Author: classiccmp(a)u.washington.edu at internet >Date: 2/24/98 1:00 PM > > > Marty, > > I have some manuals for the NS Horizon; disk controller, DOS, BASIC, > Pascal. I'm looking for the software. > > Joe > > At 12:36 PM 2/24/98 -0500, you wrote: > > Does anybody have any information on a North Star Horizon? I may be > > acquiring one of these soon but don't know much about it except that > > it has wooden side panels and used to support a half-dozen terminals. > > Is it a S-100 bus? > > > > Thanks for any help- > > > > Marty Mintzell > > > > > > > ------ Message Header Follows ------ > Received: from lists3.u.washington.edu by smtp.itgonline.com > (PostalUnion/SMTP(tm) v2.1.9i(b5) for Windows NT(tm)) > id AA-1998Feb24.130031.1767.28490; Tue, 24 Feb 1998 13:00:34 -0500 > Received: from host (lists.u.washington.edu [140.142.56.13]) > by lists3.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.05) with SMTP > id JAA14977; Tue, 24 Feb 1998 09:53:52 -0800 > Received: from mxu2.u.washington.edu (mxu2.u.washington.edu [140.142.32.9]) > by lists.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.05) with ESMTP > id JAA53378 for <classiccmp(a)lists.u.washington.edu>; Tue, 24 Feb 1998 > 09:53:44 -0800 > Received: from star1.intellistar.net (star1.intellistar.net [206.105.64.2]) > by mxu2.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.09) with ESMTP > id JAA05718 for <classiccmp(a)u.washington.edu>; Tue, 24 Feb 1998 09:53:43 > > -0800 > Received: from lizard ([206.105.68.41]) by star1.intellistar.net > (Post.Office MTA v3.1 release PO203a ID# 0-41809U2500L250S0) > with SMTP id AAA22727 for <classiccmp(a)u.washington.edu>; > Tue, 24 Feb 1998 12:53:39 -0500 > Message-Id: <3.0.1.16.19980224125410.0877b306(a)intellistar.net> > Date: Tue, 24 Feb 1998 12:54:10 > Reply-To: classiccmp(a)u.washington.edu > Sender: CLASSICCMP-owner(a)u.washington.edu > Precedence: bulk > From: Joe <rigdonj(a)intellistar.net> > To: "Discussion re-collecting of classic computers" > <classiccmp(a)u.washington.edu> > Subject: Re: North Star Horizon > In-Reply-To: <1998Feb24.123503.1767.83436(a)smtp.itgonline.com> > Mime-Version: 1.0 > Content-Type: text/plain; charset="us-ascii" > X-Sender: rigdonj(a)intellistar.net > X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN > > ------ Message Header Follows ------ Received: from lists3.u.washington.edu by smtp.itgonline.com (PostalUnion/SMTP(tm) v2.1.9i(b5) for Windows NT(tm)) id AA-1998Feb24.170757.1767.28555; Tue, 24 Feb 1998 17:07:58 -0500 Received: from host (lists.u.washington.edu [140.142.56.13]) by lists3.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.05) with SMTP id OAA07336; Tue, 24 Feb 1998 14:01:10 -0800 Received: from mxu1.u.washington.edu (mxu1.u.washington.edu [140.142.32.8]) by lists.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.05) with ESMTP id OAA35550 for <classiccmp(a)lists.u.washington.edu>; Tue, 24 Feb 1998 14:01:03 -0800 Received: from star1.intellistar.net (star1.intellistar.net [206.105.64.2]) by mxu1.u.washington.edu (8.8.4+UW97.07/8.8.4+UW97.09) with ESMTP id OAA11194 for <classiccmp(a)u.washington.edu>; Tue, 24 Feb 1998 14:01:02 -0800 Received: from lizard ([206.105.66.22]) by star1.intellistar.net (Post.Office MTA v3.1 release PO203a ID# 0-41809U2500L250S0) with SMTP id AAA26712 for <classiccmp(a)u.washington.edu>; Tue, 24 Feb 1998 17:00:54 -0500 Message-Id: <3.0.1.16.19980224170000.376726fc(a)intellistar.net> Date: Tue, 24 Feb 1998 17:00:00 Reply-To: classiccmp(a)u.washington.edu Sender: CLASSICCMP-owner(a)u.washington.edu Precedence: bulk From: Joe <rigdonj(a)intellistar.net> To: "Discussion re-collecting of classic computers" <classiccmp(a)u.washington.edu> Subject: Re: Re[2]: North Star Horizon In-Reply-To: <1998Feb24.130843.1767.83458(a)smtp.itgonline.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Sender: rigdonj(a)intellistar.net X-Listprocessor-Version: 8.1 beta -- ListProcessor(tm) by CREN

28 years, 3 months

front panels

by allisonp＠world.std.com

<But surely this is a limitation of the front panel not the processor. <I/O bus cycles can (easily) be generated from an appropriately designed <front panel. Processor. The 8080 CPU does I/O To/From the accumulator which is inaccessable from the front pannel being an internal register. An altair did things by forcing a jump(C3h, xx, zz) the address switches were used as zzxx forcing the PC to take the set value. Data at a given MEMORY address was displayed as a result of the current address and stopping before the next instructing fetch. Writing to MEMORY was simply gating the data switches and forcing a write pulse (no cpu execution). Its design was to allow insetion of code into memory and examination of memory as those were direct. IO however while it would be nice to interogate or write to devices could leave the cpu "out of sync" since all IO is done from the accumulator. To do that you really need a soft front panel and once you do that, displaying or altering the Acc, BC, DE, HL and SP registers and associated flags are possible. Did my fair share of 8080/8085/z80 designs in the '70s. Allison

28 years, 3 months

Slow But OK

by jrkeys＠concentric.net

Again things have slowed down but a few goodies were found: A Rockwell AIM65 4k computer inside what looks like a large calculator case that is black and grey in color, has a onboard thermal printer using calculator size paper, not tested yet, free; also got 6 R6500 mb's some are marked as being bad all free; a Mac IIcx missing HD and memory simms for free; a working Mac SE/30 without KB and mouse for $15; a Victor 386sx/20 laptop broken screen with power adapter for free. Other manuals gotten at thrift stores and some software that's been the week. Keep Computing - John

28 years, 3 months

BBC Model B - video help

by Philip.Belben＠powertech.co.uk

Tony Duell quoted me as having written: >> On the subject of BBC video problems, it occurs to me that the BBC micro >> does scrolling by moving the pointer to the start of the screen (under >> some conditions?). If you can get it to do this, and see how the >> display behaves, you may be able to determine easily if it's an >> addressing problem. > > Is this going to tell you very much? > > The BBC _does_ use hardware scrolling (it changes the start-of-memory > register in the 6845), but as the screen is a contiguous array of bytes, > all that a scroll does is effectively increment that pointer by the > number of bytes/line of characters (= 640 bytes in mode 0, etc) and then > clear the new bytes displayed on the bottom line. > > So the new line 0 will be the old line 1, etc, but there are no other > changes. A given byte on the screen is displayed in the same relative > position to other given bytes on the screen. In mode 0, &3281 is still the > second dot row of a character in the far left column. Of course if the > text goes all over the place on a hardware scroll then you can be > virtually certain that the 6845 is playing up. What I meant was that addressing problem _external_ to 6845 generally means that the fault will occur at the same _memory_ address. So that type of scrolling means the fault will scroll up the screen, appearing at the same place in the _text_ every time. Won't it? If the screen line length were an integer power of two, a fault in the bottom few address lines would appear at the same place on every line. Fortunately the BBC micro is 80 characters per line, so you will see things recurring on a slant. This slanted line of fault should move up the screen as it scrolls. Something to try, anyway. I am a firm believer in non-invasive tests! Philip.

28 years, 3 months

Weekend Additions

by fmc＠reanimators.org

Sam Ismail <dastar(a)wco.com> wrote: > First stop: Computer Recycling Center [list elided] Hmph. I stopped by weekend before last (14 Feb) and it looked like they'd been cleaned out. Even the bookshelves were mostly empty. Probably for the best though, given how far behind I am with other stuff that needs doing. > Corvus Systems Hard Drive unit - I believe this goes with the rest of the > Corvus Concepts computer. It has several connectors on the back labeled > "Processor", "Drive"...it also has one labeled "VCR" and a video IN and > OUT jack. McFrank, this is so you can backup to a VCR right? Yep, that's what it's for (although the hard drive could have been used with about a half-dozen different kinds of systems, not just the Concept). I'm not sure whether the jacks imply the presence of whatever you actually need to do the backup or whether there is additional hardware or software required (this is one of those things that I know I need to figure out some day when I get all those manuals in front of me at once). -Frank McConnell

28 years, 3 months

front panels

by allisonp＠world.std.com

<> The Intellec MCS8i and the PDP11 (obviously, since all I/O is memory <> mapped) do allow you to access I/O devices directly from the panel. < <...and the front panel on the Altair 8800b. The 8008 does not have memory mapped IO, there are distinct IO instructions. It's not to say MM/io is not done. The PDP-11 memory and devices are the same things and there are no specialized IO instructions. The altair...(8800 and 8800a) from the front pannel there is no way to interrogate an port mapped IO device or write to it. You must do it with a little code. Allison

28 years, 3 months

PDP diagnostic card (was Found a decent use for a PC...)

by rcini＠email.msn.com

On Mon, 23 Feb 1998 20:14:09 +0000 (GMT), Tony Duell <ard(a)p850ug1.demon.co.uk> wrote: >>I have a text file somewhere explaining how to make a functional copy of >>this unit using more modern parts (LEDs and ULN2803 driver chips, I >>think) if anybody wants it. If you can put your hands on that text file, I'd be interested in it. Thanks! ------------------------------------------------- Rich Cini/WUGNET <nospam_rcini(a)msn.com> (remove nospam_ to use) - ClubWin Charter Member (6) - MCP Windows 95/Windows Networking

28 years, 3 months

a brain... my kingdom for a brain?

by adavie＠mad.scientist.com

Tony's comment, below... about the only equipment needed to repair... was helpful. So, as I have an Altair, a BBC, a KIM, a Sorcerer and various other beasties awaiting ressurection, and having little (well, OK... no) electronics experience, starting at square 1... a) What should I be looking for in a logic probe. Any recommended models (say, <$100) b) Ditto for multimeter. c) Where can I find a brain? :) Actually, the Altair will be my first task. I'm thinking of #1 taking out all the boards. Good idea? I have it firing up and basically behaving, but some LEDs don't light when they should, but are definitely able to light when they want to. A >Hmm... I've yet to find a classic computer fault that could not be >tracked down using 3 things - a logic probe, a multimeter (DMM/VOM) and >a _brain_. On the grounds that my brain isn't that good, I sometimes have >to use other test equipment, but when I finally do track down the >problem, I generally realise that the symptoms were obvious from the >start if only I'd realised what they meant.

28 years, 3 months

front panels

by fmc＠reanimators.org

allisonp(a)world.std.com (Allison J Parent) wrote: > [....] IO however while it would be nice to > interogate or write to devices could leave the cpu "out of sync" since > all IO is done from the accumulator. You say that like there's something wrong with it. Well, there could be, I suppose, if your hardware is such that reading its registers changes them, and the operator doesn't realize this. Was the latter really considered a problem in those days? Or was it just that as a result it wasn't real useful to have the front panel do that? (Or was it just the additional cost of having the front panel do that?) -Frank McConnell

28 years, 3 months

old SCSI controller

by allisonp＠world.std.com

<The only things I know about this board is that it's a SCSI controller, a <it's BIG. It's about 10"x12", has an 86-pin edge connectr on the bottom, <two 50-pin edge connectors on the top, and uses eight 2651 SCSI chips. It <labeled "DATASTREAM ASSY 100716 REV A". Does anyone have any idea what <this is for? <TIA Sounds more like an 8 port serial board! The 2651 is a USART type device. The 50 pin connectors might be board to pannel connector cabling. Allison

28 years, 3 months

Things are getting bad

by dcoward＠pressstart.com

Anthony Clifton - Wirehead said: >I see this problem alot at hamfests. You can't blame them. They want >to bring what will sell and they're most likely to not have to carry >back home. They perceive no value to ancient computers so they assume >nobody else will either. I have 2' x 3' white board taped to the little rolling cart I take with me. On the board, I write down all the stuff I'm looking for that day. ========================================= Doug Coward dcoward(a)pressstart.com Senior Software Engineer Press Start Inc. Sunnyvale,CA Curator Museum of Personal Computing Machinery http://www.best.com/~dcoward/museum =========================================

28 years, 3 months

North Star Horizon

by Marty＠itgonline.com

Does anybody have any information on a North Star Horizon? I may be acquiring one of these soon but don't know much about it except that it has wooden side panels and used to support a half-dozen terminals. Is it a S-100 bus? Thanks for any help- Marty Mintzell

28 years, 3 months

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