Finally got a "straight" DF32 yesterday

From: John B <>
Date: Thu Nov 4 14:23:23 1999

-----Original Message-----
From: Ethan Dicks <>
To: Discussion re-collecting of classic computers
Date: Thursday, November 04, 1999 2:42 PM
Subject: Fwd: Finally got a "straight" DF32 yesterday

>--- John B <> wrote:
>> Looks like the PDP 8/S will be running a lot more than FOCAL in the near
>> future.
>> Yesterday in our snow storm I picked up:
>> DF32 with docs and "Disk Monitor" paper tapes. This is the first series
>> DF32s with the "R" series modules and no "8I switch".
>What's the -8/I switch? I have several DF-32's. All well used and not
>necessarily working (I have played with them but never really tried to use
>them for storage - the rotation sensor has been verified on at least one
>drive, but that's about it). One set came with the straight -8s, another
>set came with the -8/I.

Depending on the DF32, I have found two transistor versions. One with a
rotary switch on the right side of the front and one without. The switch
allowed you to select "PDP 8, 8/S, 8/I". I went through the logic today and
all looks good. (I am NOT spinning the drive up.....yet).

>If you get this working, I'd love to get a copy of the tapes - I have
an -8/I
>that may someday have 8K on it (if I sacrifice an -8/L by stealing its
>I have N machines that use them and (including the second field on
the -8/I),
>N-2 core stacks) I'm thinking of wiring up some CMOS static RAM on the
>of an -8/L for its 4K and migrating the core to the -8/I). I could use the
>slot between the planes on the core stack for workspace It's unpopulated.

You don't need 8K for DM. It happily works in 4K of space (with FOCAL 1968
[I have two versions of focal - any idea why????]). I am just getting
together a list of tapes and boards now to help folks out. I played the dice
game today (craps - 5/8-14 ). Pretty cool!

>> This unit was wrapped in plastic
>> and was used as a spare - it looks like it was used very little. I also
>> a new spare disk for it if I need it.
>You know that the heads crash everytime you power it off, yes? They are
>kind of disks you power up and leave on forever. In the real world, when
>osmium coating wore too thin to record data, DEC FS flipped the disk once
>and reformatted.

Yes I do. People have been warning me.... and I have *one* thing to say. I
didn't get this far with this transistor computer to let some silly design
flaw stop this system from running a disc. I will modify the hardware anyway
I can to stop it from crashing (even add some solenoids to pull the heads
back if I have to!). I want to keep this system "chip" free... I almost fell
over when I saw the "disc file" had no chips too!

I will have this system done when it is running only/all transistor
peripherals it now has plus the DF32 with DM software and the 32B
Oscilloscope interface.

>> But... the DF32 needs 13 I/O cables to
>> connect to the 8/s. Anyone still selling these kinds of things?
>I do not know *who* would have that sort of thing. I have one set per
>drive. No spares. Sorry.
>> H901 Flip Chip Patch Panels - These are really sweet. You basically plug
>> flip chips in the back and use banana plugs in the front. Also, (I didn't
>> know this at the time) hundreds of those "plastic" cards for the front of
>> the H901 to make it easy to wire circuits.
>Is this the original DEC logic experimenter's board? There were two
>one for DTL, one for TTL. I got a classroom book for the TTL version when
>was in grade school. I did many of the exercises on paper since I didn't
>the hardware to try stuff out on.

Yes they are. You can find them in the DEC handbooks. These only support
A,B,R,K,W flip chips... sorry no Ms :-) . Only for the transistor stuff!

>> I am building a quick testing station with the H901s with the 8/s so I
>> quickly fix these Flip Chips so I can provide a list on my website for
>> anyone who needs one.
>I'd love to see pictures.

I am putting pictures online this weekend and will update everyone here. I
installed the H901 panels on the 8/s so I can start some "testing" fun. I
have to go out this weekend to buy some banana plug test leads for
interconnection. These make it a lot easier to work with flip chips.
I think I am going to have our graphic designer make a "No Chips Allowed"
gif for the page.

>> I will update the webpage over the next few weeks to catalog the parts
>> software I have to help others with their old transistor computers.
>Perhaps in a couple of months, I'll dig down through the pile far enough to
>begin to recondition the cleaner of my Straight-8s. The dirty one was
>apparently from a newspaper and coated in ink. It has a PA-60 which is, I
>think, some kind of typesetter's interface.

Good stuff. I really enjoy restoring transistor systems.... it's made PDP
11s/newer 8s really boring. I am sure you will have as much fun as I have.

>> Updates to members here (trying to save bandwidth)
>> Chuck: I am going to storage this weekend. I will look for the RK8E
>> for you. I don't need them as I don't like any "IC" PDP-8.. well, maybe
>> 8I.
>You have maybe an extra RK8E that you aren't going to use? All I have for
>hard disk on ONMIBUS is RL01/RL8A sets. I've never had any RK stuff for
>the -8. I do have this 16-sector RK05F pack (and no 16-sector RK05J packs,
>only 12 sectors) that I'd love to read, but we've been over this on the
>list before. At this point, I'd probably have to hack one of my RK05J
>and replace the heads, realign it to match the pack, back it up, etc., etc.
>I've always wondered what's on it. I've had it since 1984 and never owned
>gear to read it.

I have 8 RK05 drives. They all run well. I use to add as many of them as I
could. I am looking for newer PDP-8 parts for folks here as I use to scrap
them up to a couple of months ago. I even found bits of an 8I I butchered 15
years ago... I could never understand how someone could get excited about a
12 bit computer in 1972 when all the big boys were 16 bit or more. If I
still have the cables he can have them. Besides, even if I tried to patch an
RK05 to the 8/s (with about 400 flip chips) I would be doing it's "chip
free" atmosphere a real disservice.


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Received on Thu Nov 04 1999 - 14:23:23 GMT

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