<>On a more serious note, I looked inside and there was:
<> A Z-80 cpu card.
<> 2 cards with 512K on them and were labled Disk something.
<
<Well, then, these are your disk controller(s). The "something" that
<comes after Disk is very important in identifying them!
Likely 512k Mdrive (ramdisk) really nice and quite a speed up for cpm.
<> A wire wrapped (home-brew looking) card that looks like the 8" drive
<>interface.
<What makes you think that it's the 8" drive interface? Look for the 50-pi
<cable coming from the drive box and figure out where it's going.
Could be anything...
<
<> Another card covered with 6116 Ram chips.
<
<32 6116's gives you 64Kbytes, a comfortable amount for running CP/M-80.
<Your description matches that of the Compupro RAM17, though lots of
<of other manufacturers made similar boards that might be in your system.
Ram16, ram17 there were other vendows with comparable cards.
Allison
Bring your copy of "A History of the Personal Computer" to VCF 3.0 so
you can get it signed by Stan Veit.
Also, Jon Titus, Horst Zuse (son of Konrad Zuse), and more.
Stay tuned for details.
Sellam Alternate e-mail: dastar(a)siconic.com
------------------------------------------------------------------------------
Don't rub the lamp if you don't want the genie to come out.
Coming this October 2-3: Vintage Computer Festival 3.0!
See http://www.vintage.org/vcf for details!
[Last web site update: 05/25/99]
Sam said:
>Its a "story" (fictional) about the early days of Apple vs. Microsoft. I
>don't even want to talk about it really. Just know it was horrible in
>every way possible.
>If anyone dares to pipe up and say they actually liked it I swear to you I
>will unleash such a torrent of rage upon thee so please don't. Keep it to
>yourself for your own good.
Ligh-en up Sam! It's not the Learning Channel and it's not the History
Channel. It's Turner, and they just colorized history a little. Partly
to keep the audience interested and partly to squeeze it all into 2 hours.
I enjoyed all of the scenes that take place in Albuquerque. (MITS, the
hookers, Bill getting arrested). :)
You just have to remember that not everyone on this list lives here in
California. In other places it not considered polite to tell people what
they can't think, what they can't say. :)
--Doug
=========================================
Doug Coward
Press Start Inc.
Sunnyvale,CA
=========================================
<>There are only three voltages on the bus, +8VDC, +12VDC, and -12VDC, whic
<>in reality are usually closer to +10~12VDC, +16~18VDC, and -14~18VDC.
A good way to soft start a old powersupply that is also short safe is a
100-200W 110v (or equivalent for other countries) in SERIES with the
110v power. If the supply is shorted you will get a bright light,
if it's ok it will Dim gradually or quickly to a dull glow or less.
Works well for forming caps that arent totally gone.
It's cheap and easy to make.
Whille the lamp is in series with the source you can check the unloaded
powersupply voltages, if the look good you can use an auto 12V bulb for a
1A load or a headlight for a 5-8a load.
Allison
>I wonder if you could cast one using that stuff that classic car
>restorers use to make rubber parts [an aside : Anyone know where to get
>that in the UK?]. Making the mould would be fairly easy, I think.
I always carved new ones out of pink rubber erasers, and they seemed
to work fine for me.
Tim.
<Well, I think I'm going to have to disagree with you on that one - the
<motherboard itself was mounted on a square of sheet metal which was
<screwed into a real wood casing. Extra pieces of sheet metal were added
<to the inside of later versions of the Apple 1 to improve durability and
<lifespan, but the case itself was wood, not metal. If the Apple 1
<featured in those pics has a metal case with contact paper stuck over
<it, then it's a replica, not an original.
Many that were bought as boards and cased elsewhere. The Apple 1 was the
first of the fairly complete machines (one or multiple board). The apple
II ( or ][) was significant in the construction including the molded case.
Allison
Well, much to my amazement, at lunch today, I got
an IMSAI 8080. In beautiful condition, a few small
scratches, almost no dust. Hasn't been up in years.
I know we've done this before on this list, but...
Where should I start?
I figure:
1) pull all cards.
2) attach dummy load and check PS voltage
and amperage.
(What is an appropriate dummy load?)
3) check front panel mechanically. Use an
OHMmeter to be sure that all switches are
opening and closing correctly? I seem to
remember that some people said that front
panel disassembly/assembly is tricky.
4) install CPU and see if it "lights up"?
Thanks,
Bill Sudbrink
>Thre is no "original" Apple 1 case
Right! We had 5 of them, no cases and the thing was a kit! Oh God, why did
we get rid of them? We mounted them behind a wall with cut-outs for
monitors and a shelf for keyboards and charged kids, mostly adults, to play
breakout etc. Sold a lot of computers that way. "Hey kid, do you know that
is a computer, and you can buy one for your own?"
Symptom: Print quality degrading on the ASR-33.
Analysis: Black tar like substance coating the print head apparently
originating on the print hammer.
I didn't look closely but was part #180502 the print head formerly made of
black rubber? Seems like it.
--Chuck
I once found a handy gadget for seeking adjacent line shorts on the S-100.
It's essentially a board with the edge connector and little else, except
that the pins on one side are connected. Since the lines tend to be laid
out alternating from one side to the other, your audible squeaker will allow
you to test one side at a time with the "other" probe tide to the opposite
side. Finding shorts is really quick and easy with this. It's easy make,
though several vendors sold them at one time. Fortunately, it's built
without the part of the board which would prevent you from reversing it, so
you can do just that. An unaltered board with the connections on one side
shorted wouldn't quite work due to the mechanical offset which prevents you
>from reversing a board.
Dick
-----Original Message-----
From: James Willing <jimw(a)agora.rdrop.com>
To: Discussion re-collecting of classic computers
<classiccmp(a)u.washington.edu>
Date: Thursday, June 24, 1999 2:20 PM
Subject: Re: Just scored an IMSAI
>On Thu, 24 Jun 1999, Bill Sudbrink wrote:
>
>> Well, much to my amazement, at lunch today, I got
>> an IMSAI 8080...
>
>Congradulations!
>
>> Where should I start?
>>
>> I figure:
>>
>> 1) pull all cards.
>
>Yep... Then I frequently do a quick 'shorts' check on the S-100 backplane
>before proceeding. Take a ohmmeter on a low resistance setting and step
>across the opposing pins with the leads. Start on pin 3, pin 53, then pin
>4, pin 53, then pin 4, pin 54, and onward across the backplane. This will
>quickly catch any adjacent line shorts. You may also reverse the stepping
>sequence in case the backplane is an oddball and the lines are interleaved
>differently.
>
>Skip pins 1,2,51,52,50, and 100, since these are the power supply pins and
>will give readings back thru the power supply components.
>
>(note: pins 1/51 = +8VDC, pin 2 = +12VDC, pin 52 = -12VDC pins 50/100 =
>GND)
>
>> 2) attach dummy load and check PS voltage
>> and amperage.
>> (What is an appropriate dummy load?)
>
>Well... (and I'll probably catch some heat for this) since the IMSAI
>supply is an unregulated linear supply (regulation is done on each
>individual S-100 card), a 'dummy load' is not really necessary for a basic
>check. (switching supplies need a load or they get unhappy)
>
>There are only three voltages on the bus, +8VDC, +12VDC, and -12VDC, which
>in reality are usually closer to +10~12VDC, +16~18VDC, and -14~18VDC.
>
>With the cards out, you can check these with a voltmeter. Now, where you
>may want to load things up a bit is for a 'ripple' test. (looking for
>bad/leaky capacitors &/or bad rectifier stacks. Although a bad recifier
>will often cause the line fuse to blow)
>
>Depending on the amperage rating of the supply, (the IMSAI is a honker!) I
>have a bank of automobile lamps (headlights for high amp, taillights for
>lower). I gang these together for the appropriate voltage/amperage
>ratings and 'light it up'! (pun intended) Then you can look for odd sags
>in the voltage, and if you have a 'scope look for ripple on the suppliy
>lines.
>
>> 3) check front panel mechanically. Use an
>> OHMmeter to be sure that all switches are
>> opening and closing correctly? I seem to
>> remember that some people said that front
>> panel disassembly/assembly is tricky.
>
>Not THAT complicated, but there are LOTS of screws, spacers, etc...
>
>Usually I just do a 'click' check on the switches, (toggle them and
>listen. Bad ones will often make either a muffled sound or no sound at
>all), and then do a function test once the panel and CPU boards are
>plugged in.
>
>> 4) install CPU and see if it "lights up"?
>
>After a final 'visual' check for bad/damaged/improperly installed
>components, etc...
>
>Ever onward! YMMV!!
>
>Regards;
>-jim
>---
>jimw(a)computergarage.org
>The Computer Garage - http://www.computergarage.org
>Computer Garage Fax - (503) 646-0174
>
>>>> Coming soon to www.computergarage.org - the CBBS/NW on-line archives
>
>>>> Coming to VCF III (2-3 October 1999) - CBBS/NW live!
>
