I'm told that some vendors shipped CP/M systems that would auto-detect
between several disk formats, e.g., 8-inch single density vs double
density, but I've never used one. Obviously the BIOS would change the
values in the disk parameter block. At what point is it safe for the BIOS
to do that? Obviously you wouldn't want to do format detection every time
the BIOS SELDSK function is called, but is it reasonable to do it whenever
READ or WRITER are called after a SELDSK of a changed drive number? Or is
there a way the BIOS can figure out specifically when the BDOS is trying to
log in a new disk?
Hi all,
I have a colleague doing a bit of restoration work and fault finding. He could really use access to engineering manuals for the StorageTek 1960 drive. Does anyone have physical or electronic copies of those?
-Colin Eby
found a few of the following:
54-14185-01 VT102 logic $50
54-14185-02 VT131 logic $50
70-19584-00 VR201 PS? $50
I should have the 101 and 132 boards here somewhere.
Shipping from around 61853. Please contact me off list if you are
interested.
Thanks, Paul
Thought I'd post this here before sending it out to the world/eBay, I
know there are a few Amiga acolytes here :).
I have a "Rejuvenator," an expansion for the original A1000, and one of
very few serious upgrades for the system. You can read more about it here:
http://www.bigbookofamigahardware.com/bboah/product.aspx?id=1775
My understanding is that these are pretty rare. It's currently
installed (and operational) in a rather beat up looking A1000 system (no
KB, Mouse, or monitor). Since installation is quite tricky (there are
approximately a million pins that need to connect to various places on
the A1000's motherboard, along with a few clips that attach in various
places) I'd prefer to include the A1000 with the Rejuvenator, since I
don't want to be responsible for detaching it :). No extra charge :).
I can post pictures if anyone's interested, please feel free to ask if
you have any specific questions.
I've really got no idea what these are worth, feel free to make me an
offer I can't refuse.
Thanks,
Josh
It's not easy being obsessive. I just can't stand it when my gear has a connector and I don't have the thing that plugs in to that connector. So, does anybody (preferably near southern California) have a DEC LP32 series printer sitting around for my VAX-11/730 to talk to?
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
>Message: 2
>Date: Wed, 11 Jun 2014 09:15:02 -0700
>From: "Rick Bensene" <rickb at bensene.com>
[cut]
>When he showed the IMSAIs to me, he said "They are yours, take them home
>with you". I was stunned, but also extremely happy and thankful.
[cut]
I really enjoyed reading this story. This is one (of the) reason(s) I really
enjoy this list. I could almost feel some of your enthusiasm when you were
offered the two IMSAIs.
Fred
The week before last, my wife and I took a trip to the Missoula, Montana
area to do some dog-related activities (my wife competes with our German
Shepherds in Canine Agility and Sheep Herding). Along with that, I had
recently re-connected with my old High School computer science teacher,
whom I hadn't seen since 1978 (I graduated in '77), who lives in the
Missoula vicinity.
When we arrived at my teacher's home, it was like we picked up right
where we left off, even though many years had passed. It was so
wonderful to see him again.
After we'd settled in and visited for a while, he took me down to his
basement, and there sitting on a table were two IMSAI 8080 computers!
Back in my junior year of high school, I pestered my teacher to purchase
a computer kit to be built by the advanced computer class as an
educational project. I researched the available 8080-based computer
kits (Altair and IMSAI) and was convinced that the IMSAI was a better
choice due to its more robust design. My teacher didn't have the money
in his budget to buy the kit, so instead, he bought it with his own
money - a clear indication of his commitment to education. He was an
amazing teacher, and I credit him for stirring up, then cultivating my
interest in computers.
We received the kit late in the school year, and got started on building
it, with the cardinal rule being that anything that was done had to be
explained and understood by our teacher. We got through building the
power supply, chassis, and front panel, but didn't complete the CPU and
memory board (ROM/1K RAM) during my junior year. The machine was
finished up early in my senior year, and with a few minor issues (LED
installed backwards, a couple of resistors that were swapped, and a few
bad solder joints) it worked. It was a great learning experience for
the team of five kids, including myself, that built it.
The school year after I graduated, a second kit was purchased, and the
same process followed to build it, as well as a some additional boards
(memory, video) purchased for the original machine to augment it.
The two machines sitting on the table were those two machines from the
school. My teacher had rescued them and took them home when he left the
school district, , and kept them all these years. The machines were
obsoleted in short order when the school district purchased a bunch of
Apple II's for a more standardized computer curriculum across the
district.
When he showed the IMSAIs to me, he said "They are yours, take them home
with you". I was stunned, but also extremely happy and thankful.
The machines were a bit hodge-podged. One was stuffed with boards, and
the other was minimalist.
The first machine, the one that I was involved with building, had a the
original CPU, ROM/RAM, Front Panel, and 3P+S I/O board, along with a
Processor Technology (PT) Video Board, PT CUTS cassette interface, a 32K
DRAM board, and two 16K RAM boards. The second machine had only the
Front Panel, original CPU board, and a 64K DRAM board.
The first machine was in nice shape, but three front panel toggles were
missing. The second machine had some scuffs on the front panel, but all
of the switch toggles were there and in good shape. Along with the
computers, there was a big stack of original documentation for them.
When I got home with these treasures, I focused on getting the machine
that I'd help build running. I first went through the power supply, and
found that even after all of these years, the big caps were still good,
and it was delivering clean unregulated voltages within specifications.
Then the front panel, CPU, and the ROM/RAM board were installed, and it
was slowly powered up with a variac. It came up properly, and after a
RESET, it was clear that there were some issues. The front panel was
"twitchy", operating erratically. Setting an address in the front panel
switches and operating EXAMINE would result in some bits being on where
the switches were off. The problems were fixed by reseating all of
the ICs on the front panel in their sockets...they were all secure, but
the sockets were not the best quality, and there was probably a little
oxidation here and there that caused some problems. A couple of the
switches were also a little flakey, which were traced to "less than
optimal" solder joints that were easily cleaned up.
After a little tinkering, I could reliably deposit data into the 1K
memory, and examine it back accurately. A little memory test program
verified that the memory was working well, and that the CPU was working
as it should. I then added more memory, first installing the 32K DRAM
board and verifying it worked, then adding another 16K board and making
sure that it worked. I then put the PT video board in, and could poke
data into the display memory from the front panel, and it too worked
great. Given that three switch toggles were missing, I tried putting
the front panel from the other machine in, but it was quite messed up,
so I just stole three of the toggles from that front panel to make the
original front panel complete.
I have yet to get the CUTS board installed and checked out, as well as
getting the 3P+S board reconfigured to use RS-232, as it was configured
to use current loop for an ASR-33 teletype that was used on the system
originally. Then, I am going to dig into the second system and see if I
can get it running, and find some kind of serial I/O board.
Needless to say, I'm really happy to have these great old machines. It
is really special to me that I'm reunited with the system that I
instigated and helped to build so many years ago.
Rick Bensene
The Old Calculator Museum (along with some old computers, too)
http://oldcalculatormuseum.com