> On Sun, Jun 25, 2000 at 09:48:57AM -0400, Douglas Quebbeman wrote:
> >You can buy a brand-spanking-new IMSAI 8080 that has 1 meg
> >of bank-switched static RAM and a 20mHz Z-80 (actually Z-280?)
> >processor for under US$1000. I'd say that qualifies for an
> >excellent "old" new computer.
>
> Actually last time I checked, you could only *order* that machine, not
> buy one, as they didn't/don't exist yet (still debugging the prototype).
> And it's not an IMSAI 8080 by a long shot, it's a completely different
> machine stuck in a familiar-looking box. So it doesn't address the
> original poster's point of building a better-than-1979 machine using
> 1979 components.
Point to John: the machine offered for sale is called an
IMSAI Series Two, not an IMSAI 8080. However, its arguable
that many existing IMSAI 8080s ceased being IMSAI 8080s
when the owners stuck in a Cromemco ZPU, a TDL Z-80 CPU
board, or somesuch.
However, quoting from the main web page:
: Delivery is currently 6 to 8 weeks from the date of order.
: Please check with us for confirmation of shipping date.
:
: Assembled IMSAI products are shipped factory assembled
: and supplied with a no-hassle two-year warranty on parts
: and labor UNLESS specified otherwise. See the warranty
: details on our ORDER page.
Now, I don't have a kilobuck laying around with which to
test these statements. But as to my original statement,
clearly, people spending $1200 for an original either
have little interest in running the thing, or, at very
least, want an "original" more so that they can say it
is an "original" over and above its value as a working
system. If its value as a working system is more important,
they'll consider buying the Series Two.
And if the Series Two is still vaporware, then all I can
say is that is a _very_ old tradition in the microcomputer
field, and I think I'll have to write up my experience with
Processor Technology and the Sol as an example of this (I
still have all the "soon" letters I got from them).
regards,
doug quebbeman
"R. D. Davis" <rdd(a)smart.net> wrote:
> Well, I've made the initial tests... seems that the problem may be
> before the regulators and after the fuse. Since I didn't have a 21W,
Based on the following:
> Hooking up the VOM, I got a reading of about 3.5mV for the 5V supply
> and between that and zero for everything else. So, it's not completely
> dead, but, close to it. And, yes, the fan is spinning.
...I think you may be right. The flowchart goes on to ask: "Is >= 0.6
Volts measured from A3A6TP1 to A3A1TP1? WARNING!! Use VM with
Floating GND". If the answer to this question is no, you're supposed
to replace the preregulator board (A3A1) or the control board (A3A5).
Else, the next question is whether fuse A3A6F1 is blown or missing,
in which case you're supposed to replace the fuse, else replace
transistor A3A6Q1.
Then you go back and look for +5V CPU on the crossover board again.
How to decode some of those numbers:
Leading A3 is the power supply.
A1 is the preregulator control board, which is a vertical board
plugged into the power supply motherboard just behind the terminal
block near the front of the 1000E.
A5 is the control board; it's the vertical board all the way at the
back of the power supply.
A6 is the power supply mother board. A6F1 looks like it should
be a fuse a little bit behind A1, and A6Q1 looks like it should
be the largish transistor closest to that fuse.
> > adjustment is the +5V ADJ potentiometer that is visible on the power
>
> Does adjusting that make a difference with any of the other voltages?
I don't know. The next couple of tests that the flowchart takes you
through are simply "is <some power supply voltage>" in tolerance at
the crossover board?", and if the answer is "no" then you get to
replace a transistor on the power supply motherboard, or in one case
the power supply motherboard.
> What's the difference between M and I/O in the supply v. column?
I think M is the supply that goes to the memory bus, and I/O is
the supply that goes to the I/O bus.
> Something tells me to leave this pot alone at this point.
Yep.
> As I don't have a set of schematics, can anyone tell me what to check next?
> Meanwhile, I guess I'll go poking around and see what voltages I can find
> in various spots.
As Tony points out, there is stuff in there that can knock you on your
hindquarters or worse, and I'm guessing that's why you're supposed to
use a voltmeter with a floating ground in one of those tests above.
Be careful.
That said, sorry to take so long writing back, just haven't had time
or space between my ears to sit here with the manuals and try to
figure things out from them. The curse of gainful employment strikes
again.
-Frank McConnell
No your wrong.
I have an AMPROLB, Kaypro (with Turborom) and
a VT180 board set up that way. If you having problems
with 3.5" media, stop using recycled AOL disks and
trash out the bad drives.
Allison
-----Original Message-----
From: R. D. Davis <rdd(a)smart.net>
To: classiccmp(a)classiccmp.org <classiccmp(a)classiccmp.org>
Date: Saturday, June 24, 2000 11:12 PM
Subject: Re: Where can I find 5.25 DS/DD disks?
>On Sat, 24 Jun 2000, allisonp wrote:
>> If all else and it's possible, upgrade the drive used to a 3.5". Some
>
>Not necessarily a good idea. 3.5" floppies aren't as durable as 5-1/4"
>floppies.
>
>--
>R. D. Davis
>rdd(a)perqlogic.com
>http://www.perqlogic.com/rdd
>410-744-4900
>
At 09:06 AM 6/23/00 -0400, Steve Robertson wrote:
>> -----Original Message-----
>> From: FBA [mailto:fauradon@mn.mediaone.net]
>> Sent: Thursday, June 22, 2000 6:04 PM
>> To: classiccmp(a)classiccmp.org
>> Subject: Re: Yo
>>
>> Even though the reply had a funny touch to it how else do you
>> expect to have
>> your collection survive you?
>
>When I die, my collection is up for grabs... First one here can have it all.
>Steve Robertson <steverob(a)hotoffice.com>
That's an idea but I'm afraid that between you and Mike "DogAss" I
wouldn't live very long. :-/
Joe
--- "Charles P. Hobbs (SoCalTip)" wrote:
TI, at one time, was planning to offer additional speech words through
plug-in rom modules. (The basic Speech Synthesizer only has about 250
words in it). TI changed its mind, and offered additional words via
the "Terminal Emulator" cartridge.
--- end of quote ---
Wow -- I need to take another look. Owen said the same thing yesterday, and like I told him, I can't even see where a plug-in module would make contact with anything but plastic. Weird.
Thanks for the info!
-- MB
Just a note to the group:
Maxell still produces 5.25" DS/DD media with a "lifetime" warranty.
(Lifetime of what -- me or the diskette???)
They are available for $5 per box of ten from MCM Electronics:
www.mcmelectronics.com
or
1-800-543-4330
As Allison mentioned, the diskettes will probably outlast the drives!
Regards,
Glen
0/0
> >You can buy a brand-spanking-new IMSAI 8080 that has 1 meg
> >of bank-switched static RAM and a 20mHz Z-80 (actually Z-280?)
> >processor for under US$1000. I'd say that qualifies for an
> >excellent "old" new computer.
>
> First Z280 didn't need bank switch as it had a 24bit MMU. Second if
> it has Z280 production would be hard as Zilong endof lifed it some 6
> years ago.
>
> Likely is Z180 or Z380.
You're right, it's Z180, I wrote that part of the post before
doublechecking the web page, then didn't edit the earlier
writing.
-dq
Well finally got all of the stuff off the van and into storage, plus
picked up some other goodies at the thrift's in the last couple days.
Here the short list minus items not 10 years old or older.
1. Apple RGB monitor model A9M0308
2. Computereyes Video Digitizer B/W for the Mac
3. Box full Apple cards for the Apple II series.
4. Box of early Mac mice and cables
5. HP Thinkjet model 2225D
6. Kodak DataShow in box cat # 809-3346
7. TI Silent 700 Data Terminal with the adapter not tested yet.
8. HP Apollo model 715/50
9. IBM 3196 Display Station Problem Solving Guide
10. Another HP 9144 16 Track model 9144A
11. HPJet Direct cart
12. Epson (HX20) mod for 3M and renamed Myocare Plus Programmer model
6800 with a strange cable made by LEMO.
13. DiskDrive Exerciser by Magnetic Peripherals with the following
numbers on it; TB-118A, PN 77833135E, Series code 02. No power supply
with it and it looks to have a strange connector. Anyone know about
this unit ?
Again that's the short list due ages of other items, so it turned out to
be a good week for collecting.
John Keys
>Actually last time I checked, you could only *order* that machine, not
>buy one, as they didn't/don't exist yet (still debugging the prototype).
>And it's not an IMSAI 8080 by a long shot, it's a completely different
>machine stuck in a familiar-looking box. So it doesn't address the
>original poster's point of building a better-than-1979 machine using
>1979 components.
Amen!
>- Backplane busses could have been done a lot more carefully, e.g.
> differential signal pairs, or at the very least O.C. with terminators
> at both ends (worked well for the Unibus).
Actually the S100 was cleaned up a bit and would run nicely at 8mb/s
for split or 16mb/s for unified word mode.
But multibus and STDbus were already better standards.
>- Doing fancy timing (e.g. RAS-CAS) using RC delays, one-shots, analog
delay
> lines, lots of gates in series etc. was a Bad Idea. Using a few
flip-flops
> clocked by a fast xtal clock might require an extra chip or two, but
once
> you get it working it will keep on working.
The better boards did that, alone with 4layer etch. Dram and two layers
was at best problematic.
>- SCSI-1/SCSI-2, IDE, and probably other supposedly "modern" interfaces
> could have been done with 1979 parts. At the time, the expense of
giving
> each peripheral its own CPU (or microcontroller at least) would have
been
> prohibitive, but if money were no object it would have been nice to
have
> some more open standards catch on, since the market was pretty
fragmented
> for no good reason. Floppies were absolute hell in this regard too.
Typical system with a HD in the 79-81 timeframe liekly had two CPUs
one for the HD alone! Teletek, Konan for example. There wer floppy
cards with local cpu too to further unburden the main cpu.
>- Things might have been more stable if microcomputers had separated the
> ideas of "CPU bus" and "peripheral bus" earlier on. For the longest
time,
> the peripheral bus was always just a buffered version of the CPU bus,
depends on the bus std. Multibus and STDbus for example.
> which led to lots of timing problems and incompatibilities when you
> changed to a different or faster CPU. But having something that's
easy
> to interface and has simple timing, like what the ISA bus became
(after
> having the same problem for a while), would have been a good thing, as
ISA was multibus with broken interrupts and no bus ack handshake, same
timing and interface otherwise. More interesting formfactor though.
Allison
