On Sun, October 19, 2008 1:09 pm, Chuck Guzis wrote:
>> Not to mention reliability!
>
> Yeah, but it's that nice toasty brown spot on the PCB where the
> regulator is that lends a certain je ne sais quoi to the whole
> experience. :)
Yes! :)
-Dave
--
Dave McGuire
Port Charlotte, FL
SS10 top, excellent condition
SS20 top, excellent condition
SGI Indigo 2 top (Purple), some scuffs, nice condition
SGI Indigo 2 top (Teal), some scuffs, nice condition
SGI Indigo 2 teal front 'door' plastics
SGI Indy top, very nice condition
Sun 411 case top, no scuffs or digs
Make an offer, this stuff is just taking up space.
-- Curt
>
> >
>
> PL/M was my favorite language. In those days I was designing and
> programming control and data acquisition systems for automotive R&D.
>
> How do you have Intel compilers and assemblers running on the Imsai?
> You must have ISIS-II running on it. How much work was that to do?
>
> Dave
I wish! Although it isn't a bad idea, if one could find the source to
ISIS. I am running the ISIS simulator in a DOS box in WIndows XP which is
running in Parallels on my Mac Pro quad procesor. I use ZTERM on the Mac as
a dumb terminal and load programs using the 'send text' command. I wrote a
hex loader into the SCS monitor which I have in EPROM in the IMSAI so I
just send the hex output from OBJHEX to the loader through zterm. I am now
working on the floppy primitives and perhaps eventually will try to get CPM
running. ISIS would be more fun, any idea where the source is?
I did a consulting gig with an automotive diagnostic company in Kalamazoo,
MI back in 1979 when I was working at National Semtconductor. Great fun,
although I had NO idea what I was doing, being less than a year out of UC
Berkeley. Those were heady days!
Jeff E
--------Original Message(s):
----------
From: M H Stein[SMTP:dm561 at torfree.net]
Sent: Sunday, October 19, 2008 5:11 PM
To: 'cctalk at classiccmp.org'
Subject: Req: Help/Advice on Cromemco System
-------------Original Message:
Date: Sun, 19 Oct 2008 01:29:14 -0400
From: "Roy J. Tellason" <rtellason at verizon.net>
Subject: Re: Req: Help/Advice on Cromemco System
<snip>
The catch, though, is that the System 3 needs a +24V supply as well, for
the FDD. I have one, and it uses an oddball connector, too, which is one
of the reasons I haven't gotten around to fixing the drive yet (which has
problems), I need to make an extension power cable for the drive so it can
be powered up and out in front of the case.
(Snip)
----------------Reply:
Sounds like you've got one of the later System 3's with a Tandon TM848;
the older ones used dual-slot Perscis, which used 110VAC for the motor.
And of course he could also use a 5 1/4" drive instead.
m
---------Correction:
It's been a while, and memory's fading - of course the Perscis also used
24VDC, for head load etc, so yes, that's a snag unless he uses 5 1/4s.
m
-------------Original Message:
Date: Sun, 19 Oct 2008 01:29:14 -0400
From: "Roy J. Tellason" <rtellason at verizon.net>
Subject: Re: Req: Help/Advice on Cromemco System
<snip>
The catch, though, is that the System 3 needs a +24V supply as well, for
the FDD. I have one, and it uses an oddball connector, too, which is one
of the reasons I haven't gotten around to fixing the drive yet (which has
problems), I need to make an extension power cable for the drive so it can
be powered up and out in front of the case.
(Snip)
----------------Reply:
Sounds like you've got one of the later System 3's with a Tandon TM848;
the older ones used dual-slot Perscis, which used 110VAC for the motor.
And of course he could also use a 5 1/4" drive instead.
m
----------Original Message:
Message: 28
Date: Fri, 17 Oct 2008 18:01:40 -0700
From: "Chuck Guzis" <cclist at sydex.com>
Subject: Re: Req: Help/Advice on Cromemco System
On 17 Oct 2008 at 12:21, Dave McGuire wrote:
> > Since I have been unable to find any power supplies which provide
> > the +/- 8 and +/- 16 volts, I just thought of an idea the other day
> > of using a PC power supply and shorting out the on-board voltage
> > regulators to allow them to work at the +5V and +12V of the power
> > supply. In order to do that though, I would need a small (3-5
> > slot) motherboard to test a couple of cards together.
>
> I don't think it's going to be possible to short around the +5 and
> +12 regulators in a PC power supply, as they're not discrete in that
> way. Your best bet (IMO) is to surf eBay for an big open-frame
> linear power supply.
Brute-force linear is definitely the way to go.
I'd be tempted to grab a couple of filament transformers, a couple of
bridge rectifiers and some big caps. The great thing about S100
power supplies is that PSU regulation isn't important. A 6.3VAC
filament transformer hooked through a bridge rectifier and a big
electrolytic should be close enough. +/-16 could be furnished by a
small 12.6v transformer.
The real job of regulation is furnished on each board (usually
something like 78xx 79xx linear regulator ICs).
Cheers,
Chuck
--------------
-----------------Reply:
A misunderstanding, I think: he's talking about shorting out the
regulators on the *cards*, not in the PSU, and running regulated
+5 & +/-12 on the bus; should be doable with a heavy enough
bus and sufficient bypassing, in fact I think some manufacturers
did indeed do just that.
I have a Cromemco PSU BTW, but probably not worth shipping.
mike
Hello all,
This is a slightly modified version of the message that I've posted to comp.os.vms. Wanted to see if anyone here might have an idea.
I'm trying to prepare an old AlphaServer 1000a with installed video card for an installation of VMS or Tru64.
The difficulty starts when I turn it on. Sometimes the LCD on the front is active and displays the self tests and beeps once. More often than not, however, it remains blank and there is no beep.
When the LCD _does_ turn on, the blue SRM console appears _temporarily_ some moments later on the monitor. For example, I notice that the tests have been successful and the machine gives me the ">>>" prompt. Then, about 1 min later, the screen goes dark -- even if I'm in the middle of typing something!
Any ideas?
Thanks,
- Alex
I have most of the stuff to put together a System 3. I have the card cage with the 21-slot motherboard and a bunch of cards. The manuals I got with the system include the Cromix manual, I have more than 1 64-K RAM card and at least one TPU, so I believe that mine was a multi-user system. I would like to put this back to near-original, but need a case and power supply.
Since I have been unable to find any power supplies which provide the +/- 8 and +/- 16 volts, I just thought of an idea the other day of using a PC power supply and shorting out the on-board voltage regulators to allow them to work at the +5V and +12V of the power supply. In order to do that though, I would need a small (3-5 slot) motherboard to test a couple of cards together.
If anyone has any of these available, I would be interested in obtaining them. I do not have much money, but do have some other old computer stuff that I can trade: a VAX Station 2000, an old Sun workstation, many, many old PC parts and systems, lots of electronic parts, lots of microcontroller stuff including several Dev Kits.
Also if anyone has done this before please let me know how it went.
Thanks,
Art
