Joe,
I googled "Tektronix 7J20" and a posting appeared on which you asked a
question about this unit. I know that it was 8 years ago, but do you still
have your 7J20? Is it for sale?
I repaired one of these for a friend and would like to get one for myself.
Regards,
Erick Steinberg
Mill Valley, CA
Date: Thu, 24 Apr 2008 15:47:39 -0500
From: Jules Richardson
> Hmm, maybe the designers were sensible, and any critical timings are
> solely on the device response side - i.e. the host can take as long as it
> wants to process things, but the device must respond within a certain time
> period (and then just happily sits there until the host acknowledges).
QIC-02 is buffered via drive-local RAM, so it's not really fussy on
the host-side timing. These tapes are streamers, however, so you
want to keep the tape moving; otherwise, it's back-up-a-piece-and-
take-a-running-start-at-reading-the-next-block. Really slow--and
hard on the tape.
> Of course none of this probably helps Chuck, who quite possibly doesn't
> want to be messing with designing hardware and writing driver software :-)
> It's just nice to speculate that it could be done once QIC interface
> boards are unobtainable...
Oh, Chuck has both QIC-36 and QIC-02 ISA inteface boards. He just
wants the convenience of not dealing with buggy NetBSD drivers (the
Linux QIC-02 drivers don't work at all anymore) and not having to
look for spare DMA and IRQs for the boards. A QIC-02 host interface
board is scarcely more complicated than an IDE interface. OTOH, a
QIC-36 interface is usually a full-length board, packed with a data
separator, CPU, RAM and other logic. From the CPU side, both appear
as pretty much the same thing.
Cheers,
Chuck
A local (Switzerland) auction site lists an IBM system 32 for a very moderate 50 CHF ( 50 USD)
I'd take it if my time & infrastructe budget would have had any room.
Jos
Does anyone recall what the maximum memory was for an original IBM 5150 PC at
launch time?
The way I recall it, IBM only offered 64KB expansion cards back in the day
(256KB ones came later) and the 5150 would only take four of them (wasn't the
fifth expansion slot wired differently or something)?
That still gives a maximum of 320KB of memory though (4 x 64KB, plus 64Kb on
the motherboard) - yet I was remembering the maximum total memory as being 256KB.
Maybe just bit-rot on my part. Or did the motherboard memory somehow get
disabled if memory expansion boards were in use? Or was there some kind of
maximum limit dictated by the 5150's BIOS?
I'm sure other things could be done later on via third-party boards of course
(or via the 256KB expansion boards), but in the context of the thread that I
found myself involved in, the question was what the maximum memory config in a
5150 at launch time was...
cheers
Jules
Date: Thu, 24 Apr 2008 08:38:36 -0500
From: Jules Richardson
> Does anyone recall what the maximum memory was for an original IBM 5150 PC
> at launch time?
Vividly. 64K of 4116-type DRAM chips. The first row was soldered
in, the remainder were in sockets. It was possible to purchase a
really-stripped-down 5150 through various sources (probably gray-
market as I doubt that IBM sold them that way) with no cards or disk
drives and only the first 16K installed on the planar. I believe
that the San Jose Computerland offered that deal fairly early on. I
was never able to determine if they purchased the boxes that way or
canibalized the RAM for other machines. There was a DRAM shortage on
at the time.
Cheers,
Chuck
Hello My name is Leti Meyer and teach Moderately Mentally Impaired
folks in Chandler AZ. During the 80's a Company named Edmark made a
great functional reading series for the Apple II. I have the soft
ware - I have and apple IIgs computer and I have an Echo II card and
speaker. What I don't have is drivers to install the echo II device
and no clue what slot to put in the computer and how to get it to
work. Can you help me??? I would be very grateful. I have 3.5
drive and 5 floppy drives but no way to get the appleIIgs on the web
to download the drivers. I will send a picture of my students using
it if someone helps me :)
I received a Digilog 800 protocol analyser a while ago. It's essentially a
portable/luggable (50 lbs(!)) multibus-based computer from 1985 with:
- built-in 10" colour monitor
- flip-down keyboard
- ST-2<something> hard-disk (ST-225?)
- 3.5" floppy
- 6-slot multibus backplane
- three(!) 80186 CPUs along with an AMD 29116 and an 8085.
The multibus boards all appear to be of proprietary design, rather than
some off-the-shelf boards.
I don't know why there are so many 80186's. I suppose one might construe
it as an unintended comment on the computing power of the '186.
A little googling finds some period marketing info:
"the model 800 operates at 256 kb/s, is equipped with a 10-Mb Winchester disk
and has nine soft-function keys and a 10.5-inch color CRT."
and refers to it as a "4th generation protocol analyser".
Powered up it goes though a couple of self-tests, fails on a Winchester boot
problem, requests a system floppy be inserted (which of course I don't have)
and hangs, and of course I received no manuals.
On the one hand it was pretty good stuff for it's time, might be an
interesting architecture, and speaks to a particular time and need in networking
development.
On the other hand, the lack of docs, complexity, and limited and outdated target
application leave me with difficulty coming up with a compelling reason not
to scrap it.
Anyone know anything more about it, or have any interest in it?
(location is Vancouver, B.C. area)
Someone on this list is buying an S100 chassis from me and had me remove
the 18-pound transformer to save on shipping. This transformer is now
available to anyone on this list for $10 plus shipping. Since it's small
enough to fit in a flat-rate US Priority box, I presume shipping will be
$8 to $10. Because it has two bobbins and was the only one in the
chassis, I presume it outputs both 12 and 8 volts.
And you, the buyer of the chassis, I've finally gotten to the bottom of
the messes that were in the way of proceeding. More info is in your email
spool.
--
David Griffith
dgriffi at cs.csubak.edu
Date: Thu, 24 Apr 2008 21:05:12 +0100 (BST)
From: (Tony Duell)
> I would be suprised if the QIC02 specificiation isn't avaiable
> somewhere...
Oddly, it's not on the http://www.qic.org site, but you can find both
it and the QIC-36 signal descriptions in the Wangtek PC-02 and PC-36
tech manuals on bitsavers.
Cheers,
Chuck
