Re: [midatlanticretro] Acquired a PDP-8/E
- On 05/20/2013 12:09 PM, Kyle Owen wrote:
> Yeah, the Sharpie marks made me sad too. Depending on what the switches areYes, I'd err on the side of mechanical polishing rather than chemical.
> made of, I may can use a light solvent, but I think a slight polishing would
> actually do a better job.
That's very old plastic.
> Also, the top case doesn't seem to latch on. I seeThose are little plastic snap-latches. I don't think I've ever seen an 8/e
> two plastic squares screwed into the top case, but I don't see how they'd
> match up to anything on the power supply side to latch the case down. Do you
> have some photos of that side?
on which they worked right. I'd not worry too much about them.
> Speaking of switches, the SW handle is completely broken, and 0, 1 and 2 ofWell you can usually get away without SW, but you'll need 0/1/2. Let's try
> the address/data switches also are touchy. 0 feels as though it's busted and
> can be moved horizontally, and makes bad noises when switching up and down.
to ascertain why they feel funny.
> Are replacement switches as hard to find as I'd think they'd be? I'd probablyThe switches are fairly standard slide switches. I've never had to replace
> need just one yellow and a couple of orange ones, if 0 and 1 are broken. Was
> the common failure point on these simply the handle itself, or the innards
> holding it to the machine?
one, but I'd be surprised if that were tough.
The handles have little pegs that stick out on each side, and they snap
into little metal brackets that are attached to the individual switches.
Those little pegs break off.
> I can probably get a variac and bring it up nice and slow, but I know that itCool! I'm guessing your electrolytic capacitors are probably ok. I'd
> was certainly operational within the last 10 years. It came from Auburn
> University surplus in the 90s and was previously installed in the
> microfabrication lab as an embedded computer driving a step and repeat camera.
still bring it up disconnected from the backplane first to check the PS
voltages, though. Let me know if you need the pinouts.
> I have a photo of the tops of all of the boards in that album, but I can takeOh? I didn't see that, sorry...imgur's user interface gives me heartburn.
> all the cards out and examine them individually.
I will go back and check it out.
> Will do! Are the keys all the same, or did each switch have its own matchingThey're all the same, labeled "XX2247". I keep on on my go-everywhere
keyring, for luck. :)
> This has certainly been a "dream machine" for a long time. The front panels:-)
> were the best, and finally getting to play with one will be a real treat.
> Thanks for the tips!
Dave McGuire, AK4HZ
New Kensington, PA
- On 06/06/2013 12:54 PM, Kyle Owen wrote:
> That looks like a nice product, but yes, it's certainly expensive. I've gotOS/8 needs a random-access storage device; paper tape won't do it.
> some FPGA background myself, along with several different microcontrollers,
> so I may see about creating something that will work with my high-speed paper
> tape interface. That could be considered an OS/8 storage device, yes?
Magnetic tape drives are *physically* sequential-access, of course, but the
TU56 (for example) is logically a random-access, block-oriented device. (with
highly variable latency ;))
> I wouldIf this was a generally-directed question...The book you want for "most
> have no idea how to go about writing a driver for it yet, but perhaps it'd be
> in my best interest to start reading up on the commands for the card and then
> learn more about OS/8. Do you have any suggestions on recommended reading for
things OS/8" is the "OS/8 Handbook". It is excellent. Try to find a paper
copy if you can, but it's available in PDF on bitsavers:
Dave McGuire, AK4HZ
New Kensington, PA