http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=190038705808
I'm actually quite interested in it, but it would be a bit of a trek to
pick it up. Is there anyone down there that wants this, or better still
collect it and bring it about half-way up the UK so I can meet them?
Gordon (with not enough weekends and evenings to drive the length of the
country, sadly).
On Oct 13, 2006, at 2:32 PM, woodelf wrote:
> So how many people have a working 24 bit computer on *this* list
> at home or in storage? I may end up building a 24/12 bit design
> ( the PCB layout and hardware design is my problem ) but designing
> a schematic is not.
I unfortunately don't have it (I had a chance, but didn't have a place
to put it), but in high school, the school had a 24-bit computer.
Quite an interesting machine. It used 8K-word magnetic drum memory.
There were two complete redundant CPUs, each with their own 8K drum.
There was a "shared register" between the two machines that could be
used for inter-CPU communication. The machines also shared a very
interesting
I/O system that was housed in a large cabinet. The I/O system consisted
of a Current Loop interface for an ASR-33 teletype (as well as paper
tape reader control), an interface for a wide-carriage IBM output
typewriter (individual typebars, not a Selectric-style device), and a
large number of digital input and output ports, a number of programmable
counters (to be used as interval timers), along with a bunch of A/D and
D/A channels.
There was also a BCD real-time clock which kept track of the time of day
in hours/minutes/seconds, and also toggled a bank of flip flops at
various rates which could be polled (no interrupts existed on the
machine) to track time in various increments (1/2, 1/4, 1/8 and 1/16-th
second intervals, if I remember correctly). There was also a set of
thumbwheel numeric input switches which could be read, which, if I
recall correctly, was 6 digits long, BCD encoded. The machine was all
transistorized. No ICs anywhere.
The machine was made by 3M Corp. (Minnesota Mining & Manufacturing). It
was a process control machine. Its original use was as a natural gas
pipeline pressure monitoring and control system by Northwest Natural Gas
Co. in Portland, Oregon. After it was retired, it was donated to our
high school.
When I started at the high school, one of the drums had failed, so one
CPU was inoperative. But, the other worked well.
It was a two address machine, with operand address, and next instruction
address. Addresses were of the form block/track/sector as the drum was
organized. The instruction set was pretty simple, there were five bits
in the opcode. There was an accumulator (24 bits), and a "B" register
which could be used for temporary storage. The accumulator and B
register were discrete registers, not located on the drum. Master
timing for the machine was generated by a pre-written clock track on the
drum, so all operations of the machine were synchronized with the drum
rotation. Some kind of phase locked loop or the like was used to keep
the drum rotating at a consistent speed (I think it was 3,600 RPM). The
instruction set documentation had a "for optimum programming" section
for each instruction, which provided formulas for the operand address
and next instruction address to minimize the access time for the
instruction. Typically, the operand address was the current address +
3, and the next instruction address was the current address + 6. Using
these formulas would mean that the operand would be under the head after
the instruction was fetched and decoded, and the next instruction would
be under the head when the operation was completed.
There were no index registers or base registers or anything like that.
Addressing tables and such had to be performed by instruction
modification, e.g., load an instruction into the accumulator, increment
(or add 3 for optimum programming) to the operand address, store the
accumulator back over the top of the instruction, then execute the
modified instruction. Made list processing, stacks, and the like rather
tedious.
Each CPU was in a "drawer" about 8 to 10 rack units high. The drum was
located in the center of the chassis, with circuit boards (which, IIRC,
were about 7" long, and 5" wide) plugged into a backplane in the shape
of a "U" around the drum. The two CPUs mounted in a small rack one atop
the other.
Controls for the CPU were simple. STOP, START, CLEAR, and LOAD. Clear
cleared all of the working registers, and set the program counter to
Block 0/Track 0/Sector 0, and halted the machine. Stop halted the
computer after the execution of the current instruction was completed.
START began program execution. LOAD put the machine into a hardwired
loader that would allow address/data pairs to be loaded into the drum
>from the paper tape reader on the ASR-33. The address and data were
expected in octal, with a space separating the address and the data.
These controls were momentary pushbuttons, with the START, STOP, and
LOAD buttons lit to indicate when the machine was running, halted, or in
LOAD mode. Five indicators would show the opcode of the current
instruction. I seem to recall that it was possible to
single-instruction step the machine by putting the machine into STOP
mode, then holding the STOP button down when pressing the RUN button at
the same time, but this memory could be incorrect.
There was a two-pass assembler called SOAP that could be loaded from
tape, then the source run through the paper tape reader twice, with the
resulting object code stored on the drum. SOAP was pretty big, though,
about 4K resident, which meant that you couldn't write anything much
larger than about 4K in size with the assembler.
I had spent time at the Oregon Museum of Science and Industry (OMSI) on
their "Straight 8" PDP-8 System, and had learned FOCAL. I decided to
try to write FOCAL on the 3M machine. I actually got to it to the point
where small programs could be entered, edited, and executed. It did
integer math only (24 bit), as floating point simply wouldn't have fit.
When a line of code was entered, and the RETURN key hit, it would take
about 1.5 seconds for the line to be parsed, error checked, and stored.
This machine was not very fast. I wrote quite a few programs for this
machine, including a blackjack game, tic tac toe, an alarm clock (you'd
enter the time on the thumbwheel switches, and when the time came along,
the teletype would ring the bell).
Never got the IBM output typewriter working. It had mechanical problems
(probably needed a thorough cleaning and lubrication). After I
graduated from high school, the machine didn't get much attention.
Someone tried powering it up at one point, and the drum in the still
operating CPU failed..bearings went bad, and (fixed) heads crashed. The
school eventually moved to a new building two years after I graduated,
and that's when I had the opportunity to take the machine, but I had no
place to put it, nor any way to move it. It was rather large (and
heavy).
The cabinetry was all painted a dark blue color. A white formica table
top sat on top of the two CPUs in their small rack, and on top was a
console with the real-time clock (using incandescent displays that had a
GE-47-style lamp that shined through a piece of film that had the digit
on it, which projected the digit on the a satin-finish plastic display
screen). The clock was not made by 3M, but by someone else, was about 6
rack units high, and had pushbuttons to manually advance the hours,
minutes, and seconds. It was implemented with transistor logic,
connected as ring counters for each digit. Also on this panel was the
six-digit thumbwheel numeric entry device.
The IBM typewriter sat to the right of this panel. The controls for the
CPUs were mounted on the front plate of each CPU drawer. To the left of
the CPU drawers was the large cabinet that housed all of the I/O
circuitry. It was crammed full of transistorized modules that plugged
into a massive backplane.
Each CPU had its own power supply, as well as the I/O cabinet, and the
realtime clock. Each CPU needed a 20A 110V circuit. The I/O cabinet
needed a 30A 110V circuit. The clock, IBM typewriter, and Teletype had
their own 20A 110V circuit.
I've been unable to remember the model number of this machine. I recall
that it was 4 digits long. At one time, I had a big binder which
contained a bunch of documentation for the machine, including the
instruction set information, some information about the I/O subsystem
programming, and also complete schematics for the CPU. I've searched
and searched for it, and can't find it -- so I think that it must have
been lost or accidentally tossed in one of many moves.
I've searched high and low on the web looking for any references of any
computers made by 3M, and have found nothing. My guess is that they
didn't made computers for a very long period of time. My recollection
is that the date on the documentation was 1965, but not sure of this.
Anyway, probably a whole lot more here than anyone cares about, but it
is my hope that perhaps someone out there may recall a machine like this
made by 3M.
Sure had a lot of fun playing with that machine. Learned a great deal
>from it. The mainstay computing at our highschool was an HP timeshare
system (initially, HP 2000C, advancing over the years to a 2000C',
2000F, then 2000/Access) which were accessed by dial-up ASR-33
teletypes. A "closed" BASIC environment, which was great, but no
machine-level programming. I learned a great deal about "how computers
work" from the old 3M machine.
Thanks for letting me spew out all these memories.
Rick Bensene
The Old Calculator Web Museum
http://oldcalculatormuseum.com
Hey folks. Does anyone have a Ferguson Big Board that they might
be interested in unloading? I drooled over their ads in BYTE when I
was a kid; I'd love to have one now. I have a pair of 8" drives
sitting here just waiting for one.
-Dave
--
Dave McGuire
Cape Coral, FL
I have a PDP-11/23 for sale with the following componets in three 4-
foot racks:
Pictures: http://www.schnitz.com/pdp/
Rack 1:
RL02
PDP-11/23
RL-02
The stuff sitting in front of the rack isn't related.
Rack 2:
Colorado Video Digitizer
Chroma Keyer Decoder Model 4706
Bosch unit
Another video-related piece of equipment below that
There's some wire-wrapped board sitting it the empty space below
that. I'm not sure if it's a part of the system, or if I just stuck
it there to save space. i'll pull it out tomorrow and take a look.
Rack 3:
Memory (possibly some other stuff mixed in there too, but the black
units are primarily memory)
Power Supply
Fan
Also included:
Cabinet of RL02 cartridges. I recall at least one of the tapes was
labeled "System" and something else. I can write down what they're
all labeled, if it makesa difference to anybody.)
Very large drawing tablet
The fellow I bought this from told me it was used to do computer-
generated graphics in the '70s and that it cost his company a quarter
million dollars. I think it's depreciated since then. I bought it
several years ago, but never did anything with it. It sat in his
basement, then it sat in my garage. He told me it was working when
decommissioned, but that was some time ago and it's utterly as-is.
He also said it uses the same memory (behind the black panels) as in
the Apple II.
I bought a milling machine last week and need the room, so I'd like
to see it go relatively soon. I'm in York, PA.
I also picked up some HP-85B's at an auction last week. I only
wanted two, so the rest are for sale. They came out of storage at a
very nice lab and look like they're in great shape.
Also available from the same auction is a system configured as follows:
HP 9144 (tape drive)
HP 7957B (hard drive)
HP A-Series Controller 3065ST (board tester?)
Make offer.
Tom
--
Apple I Replica Creation: Back to the Garage
By Tom Owad, Foreword by Steve Wozniak
About the book: <www.applefritter.com/replica>
OSNews Review: <www.osnews.com/story.php?news_id=10085>
I'd like to echo Henk's thanks for the discussion. I too am learning
>from this as I'm actively working on a /34a and looking at a dormant
/70.
Interestingly the /70 has an M9312 in 1AB _before_ any of the
processor boards and an M9302 (as expected) at the end of the Unibus.
Thanks,
John
>
>Subject: Re: Tandy 2000 Floppy Drive Replacement
> From: Fred Cisin <cisin at xenosoft.com>
> Date: Sat, 14 Oct 2006 13:56:14 -0700 (PDT)
> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org>
>
>> On Fri, 13 Oct 2006, Fred Cisin wrote:
>> > The Tandy 2000 uses a 720K 5.25" drive. DSDD 96tpi.
>> > Matsushita (Panasonic, Shugart, etc.) 465
>> > Tandon TM100-4
>> > Teac 55F
>> > etc.
>> > SOME 1.2M drive could work. They need to be jumpered to 300 RPM, "low
>> > density" recording current, etc.
TEAC FD55GFV jumpered for fixed speed.
>>
>On Fri, 13 Oct 2006, Marvin Johnston wrote:
>> Second, IIRC the speed and "low density" recording current are set with jumpers.
>> What is the etc.?
>
>Ready v Disk change (pin 34)
>termination
>drive select
>maybe motor on w/drive select
>
>> I might add that when connecting a standard 360K drive, the light comes on and
>> stays on, and the drive continues to spin when a disk is inserted. This gives me
>> the impression that there may be something wrong with the disk controller for
>> the Tandy 2000. The cables for the 2000 are straight-thru, so I rejumpered the
>> drive to the first drive (D0 of 0-3 or D1 of 1-4.) And yes, I checked and double
>> checked to make sure that pin 1 on the motherboard matches pin 1 on the drive!
Connector on drive upside down. Drive runs on power up with light lit, doesnt
step (may recal on power up depending on drive). NOTE: if the connector is
inverted any media inserted is erased for whatever track the head sits at
(write enable is active).
>DECMATE II Soft-Sect. CP/M
DECMATEII (and III) was a RX50 (SSDD 80tr) ~400k
Though one later option was RD31(st225 20mb) or RD32 (ST251 40mb)
hard disk with RX33 (FD55GFV). DECmateII treated the FD55GFV as
a single platter RX50 (single sided) unless teh firmware
was above a certain rev. DECmateIII knew RX33.
>DEC Rainbow
Most DEC machines prior to VAXmate used RX50 a dual
drive of 80tracks single sided and about 400k each.
>DEC Rainbow MS-DOS V2.05
Again, RX50 though RX33<teac FD55gfv> could be fitted.
RX50 remained the "Corperate" floppy drive till VAXmate.
There were a few products that used otehr drives but
usually from the start. For example Robin (VT180) used
either SA400L or TM100s (40 track single sided DD).
Allison
While doing some moving today of items to storage I found that Power
Macintosh G3 (Blue and White) tower
(family M5183) had both support feet broken. Does anyone have a extra set of
these, that they are willing give or sell real cheap? Email me off list
please. Thanks John
Sounds like you have the Floppy Cable backwards.
Try plugging it in the other way around.
You have Pin 1 and pin 40 flipped. A constant light and spinning motor is the usual symptom of that.
Another way to get data off that machine is to use LapLink V and a Serial LapLink Cable. There were several work-alikes to LapLink like FastMove and others.
You should be able to buy LapLink cables rather cheaply these days.
Al
Phila, PA
----Original Message-----
From: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org]
On Behalf Of Marvin Johnston
Sent: Friday, October 13, 2006 8:46 PM
To: ClassicCmp
Subject: Re: Tandy 2000 Floppy Drive Replacement
On Fri, 13 Oct 2006, Fred Ciscin wrote:
> The Tandy 2000 uses a 720K 5.25" drive. DSDD 96tpi.
> Matsushita (Panasonic, Shugart, etc.) 465
> Tandon TM100-4
> Teac 55F
> etc.
>
> SOME 1.2M drive could work. They need to be jumpered to 300 RPM, "low
> density" recording current, etc.
First, what other machines used a 5 1/4" 720K drive? I've been looking
through
the stash, and so far I haven't found anything.
Second, IIRC the speed and "low density" recording current are set with
jumpers.
What is the etc.?
I might add that when connecting a standard 360K drive, the light comes on
and
stays on, and the drive continues to spin when a disk is inserted. This
gives me
the impression that there may be something wrong with the disk controller
for
the Tandy 2000. The cables for the 2000 are straight-thru, so I rejumpered
the
drive to the first drive (D0 of 0-3 or D1 of 1-4.) And yes, I checked and
double
checked to make sure that pin 1 on the motherboard matches pin 1 on the
drive!
Thanks!
On Fri, 13 Oct 2006, Fred Ciscin wrote:
> The Tandy 2000 uses a 720K 5.25" drive. DSDD 96tpi.
> Matsushita (Panasonic, Shugart, etc.) 465
> Tandon TM100-4
> Teac 55F
> etc.
>
> SOME 1.2M drive could work. They need to be jumpered to 300 RPM, "low
> density" recording current, etc.
First, what other machines used a 5 1/4" 720K drive? I've been looking through
the stash, and so far I haven't found anything.
Second, IIRC the speed and "low density" recording current are set with jumpers.
What is the etc.?
I might add that when connecting a standard 360K drive, the light comes on and
stays on, and the drive continues to spin when a disk is inserted. This gives me
the impression that there may be something wrong with the disk controller for
the Tandy 2000. The cables for the 2000 are straight-thru, so I rejumpered the
drive to the first drive (D0 of 0-3 or D1 of 1-4.) And yes, I checked and double
checked to make sure that pin 1 on the motherboard matches pin 1 on the drive!
Thanks!
