>
>Subject: Re: Tarbell is making me insane
> From: Grant Stockly <grant at stockly.com>
> Date: Thu, 08 Nov 2007 11:02:00 -0900
> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>At 10:11 AM 11/8/2007, you wrote:
>>On Wednesday 07 November 2007 10:53, Allison wrote:
>> > Also sounds like oneshot problems. Check cpu timing. Even small timing
>> > errors tend to magnify bus noise issues and incompability problems.
>>(Snip)
>> > Also HEAT. That thing despite a very heafty noisy fan and cover mods
>> > didn't like heat. FYI: the timing of the oneshots drifts with heating!
>>
>>This probably explains a lot why I encounter 9602 (and the LS variant) fairly
>>often in stuff that's otherwise full of the standard 74xx (or LS) parts.
>>
>>I remember back in 1978 trying (unsuccessfully) to make an interface
>>board for
>>a dual cassette deck that we had on trial to work with the H11 system I'd
>>built for this company. The fella on the phone warned me to stay away from
>>the '123 parts for just this sort of reason...
>
>Its not the one shots... I installed a Cromenco ZPU card and it also crashes.
Some Z80 cards complicate the issue. They have diffent timing and at 4mhz
some ram MAY NOT be fast enough. Either slow the z80 to 2mhz or more wait
states from ram.
FYI: the Seals 8k [most 2102 basd cards] cards are marginal for Z80
above about 2.5mhz.
>I really wanted to get this setup working. In my experience, the
>Altair disk subsystem with a half dozen one shots is more reliable
>and predictable to the Tarbell (hehehe). And taht experience was
>with a CPU card that had one shots so out of spec according to the
>intel data sheets the 8080 should not run.
>
>Now I have a CPU card that has been tweaked to have perfect CPU clock
>timing. Nothing. : (
Also make sure the crystal osc is really running at 2mhz. Mine would
sometimes take off at 4 or 6mhz until I dumped it for 8224.
Shows how rough the bus timing and noise can be. Is that a one piece
backplane of the two sided variety or the one of the earlier Altair
4 slot chains or single sided backplane? The reason is the earlier
two styles were noisy at best and terminators didn't work well on them.
Replaced the backplne with WAMCO unit and the problem improved and
terminations worked. The front pannel still induced a lot of ringing
on the bus.
>My next guess is going to be switching the disk drive to run off of
>power from the Altair. The disk drive is getting about 5.25v from
>the AT computer power supply and the S-100 boards are regulating
>their 5v to 4.95v. I really don't think that could be a problem, but
Thats not it. Do make sure the drive and it's DC have a good common
ground.
>I'm willing to investigate anything right now. I am going to give
>the manual a close look and make sure there aren't Altair specific
>wiring instructions that were missed. I just can't figure out why it
>is going crazy! I might have to get out the oscilloscope.
You might. One thing to check. Is the raw BUS voltages at least 8V
and 16V?? I when through two sets of PS mods to get enough power
for a 48K of 8K 2102 rams, a VDM1, Altair PIO, Altair SIO plus
eventually a NS* MDS.
>I installed all of the boards in a "vintage" Altair with less luck.
Thats why mine is retired. I'd feel different if it were an 8800B.
>Grrr... This is the 3rd Tarbell card I've used trying to get
>something good. The cards are modified by someone, work PERFECT in
>his IMSAI with one of my reproduction 8080 CPU cards, and mailed to
>me. He found that he needed a terminator to make it work, so I
>installed a terminator that he sent me. The terminator only made
>things worse.
It could be the front pannel doing something to you.
Now your getting a feel for what life was like for an Altair owning
early adoptor. I still really feel that the hardware issues I fought
with delayed my developing software efforts. It was when I went to the
NS* and Netronics Explorer 8085 that I stopped chasing hardware and
started working with higher level languages and system performance.
Allison
>Grant
Date: Sun, 11 Nov 2007 09:32:20 -0800
From: Al Kossow <aek at bitsavers.org>
Subject: Re: LIST ADMIN Re: Laserdiscs (was: Video Clips)
To: classiccmp at classiccmp.org
Message-ID: <47373CA4.2070905 at bitsavers.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> > For me "classic" computers
> > are the ones created between 1977 & 1990ish & yes, this includes the early
> > IBM PC's.Until the PET thread started I was getting seriously bored with the
> > list, now it's interesting again.
>Try http://www.vintage-computer.com/vcforum/search.php?do=getdaily
>which may be more appropriate to your interests.
>You won't have to worry about people talking about anything other than consumer
>computers there.
----------------
A different population from this list to be sure, broadly speaking, but nevertheless
CP/M, DEC, Cromemco, IMSAI etc. are discussed there as well as WIN3.1, and since
it's a forum format you can pick & choose your interest.
And I agree with the OP that, certainly from a broad historical perspective of computers,
old IBM PCs, PETs etc. are just as important and 'classic' in their respective segments
as Altairs, IMSAIs and even DECs, regardless of one's personal bias.
m
Anyone on the list have IBM 1401, A User's Manual music CD? I ordered it
last week but it has not come yet. If you have it what do think about it?
John
That recent discussion on the CRC chip got me to thinking about something that
I hadn't thought of for some years now...
My Bigboard II has a bit of interesting code in the EPROM, that does a sort
of sanity check on itself. Some sort of a CRC algorithm (I'd have to dig out
the code for exact details, and have NO idea of where I'd find it at this
point).
This thing had six sockets altogether, only 24-pin, so I couldn't put any
bigger than a 2732 in them, and one of the nifty features in the code in
that one that came with it was that it'd check the _second_ socket the same
way. That way, if you had an appropriately-coded chip in there it'd just
hand off to it. Seems handy to me as a way to just get the darn thing to
boot a disk without you having to tell it to do so.
Unfortunately, I have *no* idea how one would make an eprom have the
appropriate CRC results. I suspect that one of the important details would
be the exact polynomial used to generate the CRC in the first place, and I
don't have that handy at the moment, have to figure out just where the heck
that is...
But any suggestions as to where I might research this further would be
appreciated.
For some reason, in spite of me having seen lots and lots of full-page ads in
Micro-Cornucopia and elsewhere during that time, I can find almost nothing
on the machine on the 'net these days. Which is a shame, as it's a nice
board, in a lot of ways...
--
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
All:
Now that the weather in the Northeast is cold again, I?m picking up on
some old projects, among which is the floppy system for my IMSAI.
Here?s what I want ? a 5.25? dual-disk system running CP/M 2.2 (my IMSAI
has a Z80 board in it).
Here?s what I have ? plenty of 5.25? TM100 and equivalent drives, a
CompuPro Disk 1 and an SD Sales Versafloppy (not II). The Versafloppy
specifies SA400/450, but I think other 5.25? drives will work.
Here?s what I don?t have ? a working disk image for either of the above.
Dave Dunfield has a disk image for a Disk 1A but it?s from an 8? original.
Also, the ComprPro controller seems to require modifying the IMSAI front
panel to disable it (by removing the ground on pin 20 IIRC). I really don?t
want to modify the front panel. I browsed the Versafloppy manual quickly and
it doesn?t seem to require modifications to the host machine.
Given this, does anyone have a Versafloppy image I can use?
Alternatively, I?d gladly trade what I have for a board/disk that would
work. I would even consider trading other stuff for it, including the 8?
drive system I have that is the bane of my existence.
Thanks again for any help.
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.altair32.comhttp://highgate.comm.sfu.ca/~rcini/classiccmp
Jules,
> We recently managed to (finally!) get our HP 2116 machines out of 'deep store'
> and into the light of day, and some initial cleaning work was done on the
> panels earlier.
It appears that many of the boards, especially in the 2116C, have just
been placed into arbitrary slots.
You will also need to double-check some of the part numbers on the boards
to be sure that the 2116B and 2116C boards have not been put into the
wrong chassis. For example, it may be that some of the boards in the
2116B are 2116C boards and vice versa.
I can send you a more complete list of which boards belong in which
slots, but that will be just part of the story, in order to get these
machines running.
Overall, it looks like you have close to a complete 2116C and 2116B,
though you are missing the I/O boards that would have been used
in a dual processor system.
James Markevitch
>> Another question- so far I have had two Sun-3 era machines (a
>> Carrera CPU in a CADDstation and a Sun 3/200 CPU) develop "all
>> lights on" catatonia. Is this a common problem with Sun-3s? I'm
>> wondering if I should take the time to trace out the 3/200 board
>> (preferably with hints on where to look), give it away, or junk it
>> (I have a working 3/110 system, so I won't be destitute of Sun-3s).
>>
> Not common at all...I have run literally hundreds of Sun-3 systems
> and have *never* seen that failure mode.
Check the EPROMS. Clearing the LEDs happens early in the boot process
so either the processor is totally hosed or the boot EPROMS have bit rot.
> For me "classic" computers
> are the ones created between 1977 & 1990ish & yes, this includes the early
> IBM PC's.Until the PET thread started I was getting seriously bored with the
> list, now it's interesting again.
Try http://www.vintage-computer.com/vcforum/search.php?do=getdaily
which may be more appropriate to your interests.
You won't have to worry about people talking about anything other than consumer
computers there.
Couple of questions on old Sun machines (well, parts).
On a Sun 4300 CPU board, I'm getting the
"EEPROM Write-Write-Read-Read test
error PA=0xF2000000 VA=0X00FF8000 Exp=0x0000005a Obs=0x00000000
(looping)"
error. Looking on the Web and Usenet seems to show that this has
happened a couple of times, with some reference to possibly being the
NVRAM (although the most comprehensive posing set was in German :().
This seems a bit odd, though - on my other Suns it calls the NVRAM the
NVRAM, so I'm wondering if this is something else. J1900 1-2 is
connected (4MB SIMM option), so it shouldn't be that (or is there
something else needed to be done- not sure if this is a 4/330, or if
there is any board-level reason that it couldn't use 4MB SIMMS).
Another question- so far I have had two Sun-3 era machines (a Carrera
CPU in a CADDstation and a Sun 3/200 CPU) develop "all lights on"
catatonia. Is this a common problem with Sun-3s? I'm wondering if I
should take the time to trace out the 3/200 board (preferably with
hints on where to look), give it away, or junk it (I have a working
3/110 system, so I won't be destitute of Sun-3s).
I still have 30 or 40 LD-V1000s (basically NOS) so I didn't feel too bad about
tearing one of them (that didn't work the first time) apart. What I found
interesting is that they use a Z80 as the processor. Also, most of the ones I
have gave significant picture jitter when I first checked them out. Turned out
that there is a pot inside that has a connection to where the laser is on the
disk. That pot somehow got "noisy" over the past 15 - 20 years they have been
sitting and a combination of contact cleaners made the machine operate as new
again. And the service manual is available on-line at the Dragon's-Lair-Project
website. As an aside, that website also has the diagrams to make up a centronics
plug to be able to start the laserdisk playing. *REALLY* nice for checking out a
unit! A friend of mine also has all of the alignment jigs in case I wanted to go
that far into repairing these things.
> From: Jeff Jonas <jeffj at panix.com>
>
> I pulled apart an old InfoTrac library system that used a
> Pioneer LD-V1000 since CD-ROM drives were not yet available.
> Top loader, CAV disks only. Real He-Ne laser on the sled.
> The Centronix connector was a proprietory parallel port
> controlling video playback, getting frame #
> and it allowed reading digital data if it was recorded in that format
> (video playback was still NTSC, no digital at all, not even a frame buffer).
