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Digital 32KW RAM pcb

Roland Huisman

Roland Huisman

Veteran Member
Joined
Mar 24, 2011
Messages
1,472
Location
The Netherlands
So the Omnibus 32KW RAM boards were sold out everywhere. Back in November 2018
I've made a redesign in Kicad of the 32KW memory board which mr Lafferty designed.

RAM and M847 board.jpg

It is in the same small form factor as the M847 extended version. (The board on the top)
The reason is because it's cheap to keep the PCB small. No import taxes on it etc...
I've made them just for myself, the whole idea is from Stephen Lafferty. So no credits for me here...
I've made a little mistake according the numbering of the fields at the dipswitch.
7...0 instead of 0...7. OOPS. A little sticker will solve that.

The corrected drawings gerber files and part list are on Github.
So if anyone wants to make the PCB himself you can also order them at JCLPCB.

But because I have just two machines I have 3 of the boards left.
Free to go to a new home just for shipping costs. Just one per person please.

bare boards.jpg

Regards, Roland
 
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Hi Roland!

Cool stuff. I could make use of one and Germany seems to be just around the corner ;)

I will send you a PN.

Greetings from snowy Dortmund,
Peter
 
m_thompson said:
I could use one if it is still available.
Click to expand...

Okay, then the last one is yours! Please sent me a PM with your address.

I forgot to mention Vince Slyngstad in the opening post. He has updated the original design from mr Lafferty.
The schematic is identical to that of what Vince made back then. So also thanks to Vince also for the info of the used chips!

And I wonder who will take the board from the other topic... ;) One board per person
so three people are not in the race for that board anymore :D

Regards, Roland
 
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Oh, dear, I have missed it then.

I have one of the early 32kw boards, but have four non working pdp8e machines (and a non working pdp8/L), all hopefully neading a board. All the pdp8 machines have been stored in a basement for 30 years with a dehumidifier running to reduce the damp, but the chips have suffered as no combination of boards makes a working machine. I was much better working on these machines 25 years ago.

A combination of 32k and the bootloader on the same board would be nice, as there is loads of spare room.

By the way, there are some very chep 32k x8 chips on ebay (50p each - I got 40!) and some 128kx8 for £1 each. Can a simulated tu56 be made with some of those 128k chips, I wonder?

Steve Laurence
 
Dear all,

Well, 50% of my responses to this forum seem to disappear...., as did mine yesterday.

I presume I am too late then for consideration of a board.

I do have one of the original 32k boards from sime years ago but do have four pdp8e machines, all currently not working, due to storage in my basement for 30 years. It is not too damp with a dehumidifier running but the once-working machines are now full of faults.

Incidentally there are some 32k x 8 and 128k x 8 static ram chips on Ebay for 50p and £1 respectively. However the 128k one had a highish memory retention current.

Steve Laurence.
 
Roland Huisman said:
So the Omnibus 32KW RAM boards were sold out everywhere. Back in November 2018
I've made a redesign in Kicad of the 32KW memory board which mr Lafferty designed.
Click to expand...

I've made a small run of your bootloader and the 32K memory on a full size board.

I still need to build out and test the bootloader side.

img02042019_110.jpg

Vince
 
Hi Vince,

Very nice! I didn't know you have the PCB ordered already.
Is your goal to make kit's again like you did on the RAM boards in the past?
I'm looking forward to see the end result :D

Regards, Roland
 
Roland Huisman said:
Very nice! I didn't know you have the PCB ordered already.
Is your goal to make kit's again like you did on the RAM boards in the past?
I'm looking forward to see the end result :D
Click to expand...

Yeah, things are feeling hectic, as VCF-PNW is coming up and I really want
to get a Spacewar board working by then. So I'm afraid I have been a bit
pokey about the boot+mem card.

I like the idea of the boot+mem card because it includes a serial port, which
provides everything needed (except a $5 or $10 RasPi 0 for serialdisk) to
boot to an OS. So assuming you are OK with it, and assuming board debug
goes well, I thought perhaps I could at least work off my ram board waiting
list :).

Vince
 
vrs42 said:
Yeah, things are feeling hectic, as VCF-PNW is coming up and I really want
to get a Spacewar board working by then.

Vince
Click to expand...

Vince, I want to hear more about this Spacewar board. I have thought about wire-wrapping a register compatible VC8E emulator on extra space I have on my wire-wrapped 32kW card (http://www.vcfed.org/forum/album.php?albumid=182&attachmentid=12029).

Lou

PS. The card in the album is wrapped from Chuck D's design, which is close to Steve L.'s which came later.
 
Lou - N2MIY said:
Vince, I want to hear more about this Spacewar board. I have thought about wire-wrapping a register compatible VC8E emulator on extra space I have on my wire-wrapped 32kW card (http://www.vcfed.org/forum/album.php?albumid=182&attachmentid=12029).
Click to expand...

Not a lot to tell, yet. It's a full size Omnibus card, which attempts to implement the VC8E board set and an M1703 subset input port (to save wear on your switch register). The logic for the boards is collapsed into an ATF1508 CPLD, and that mostly leaves the DACs and timer monostables as external circuits. (The DACs are modernized too, so it leaves a fair bit of board area unused.)

I spent some time today chasing down what appears to be a CUPL compiler bug that was causing my VC8E IOTs to fail. Tomorrow I get to reprogram the CPLD and see if the kaleidoscope program works any better :).

You'd still need a real time clock card of some sort, and a working EAE. (Problems for another day.)

I hope I can get it to drive my VT01/Tek611 storage 'scope (in non-store mode) for the show, but if not, I might have to settle for a tiny X-Y display on a modern 'scope.

Vince
 
Dear Vince,

If any boards surplus to requirements, I would very much like a 32k memory plus bootloader on the same card. I have 32k and 128k chips coming out of my ears. A serial i/o on the board as well would be a welcome addition in the future.

I have just invested in a PiDP8 emulator of the 8/i from ebay and now having to learn a lot about Rasberry Pi and how to get a terminal working with it, but it might also incentivise me to get some of my real machines gong.

Steve, G7PSZ
 
G7psz said:
If any boards surplus to requirements, I would very much like a 32k memory plus bootloader on the same card. I have 32k and 128k chips coming out of my ears. A serial i/o on the board as well would be a welcome addition in the future.
Click to expand...
There was some progress on this front yesterday. I had set things aside for a time, as the 8/E would not boot with the card installed. This even with all the chips removed! The bare board didn't have the problem, though, and yesterday I was able to determine that it was Q1 and Q2 holding the CPU in reset. Removing those allowed me to verify that the memory seems to be working.

I believe the issue on the boot loader side is simply that I don't have the sketch loaded into the microcontroller. I struggled with that a bit, but it looks like I'll have to go get a proper Arduino and use that for the programming. I think it's just a feature of Roland's design that you have to have the sketch loaded or the system will think you are holding CLEAR down. (Even with that transistor removed, there are 7777 on the DATA lines all the time.)

If that proves true, then it's just the programming issue that's holding things up. Well, that, a bunch of other projects, and
VCF-PNW :). Most likely after the show I'll be trying to figure out how many I have vs how many there is demand for.

Vince
 
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