• Please review our updated Terms and Rules here

Looking for storage for PDP 8

S

silcreval

Experienced Member
Joined
Mar 15, 2009
Messages
73
Location
UK
Hi,

I realise this is a long shot, but it would be great to get some kind of real storage option for a PDP 8/a. Anything considered. I'm based in the UK, but can collect from UK or near Europe - e.g. Germany/France/Netherlands/etc.

Working on an interesting new interpreter for the PDP 8 based on C-, a cut down version of C.

Thanks!

Ian
 
Thanks - I've got a setup which emulates a teletype for loading code - but would be great to have something 'real'. I guess I'm old school and like to hear the spinning drives :)
 
Thanks - I'll give SerialDisk a go. Do you know which comms cards I can use with a PDP 8/A ? The rack is fairly full although I seem to have one slot free.
 
You may be able to locate an RX01 or RX02 dual 8" floppy drive unit from a PDP-11 somewhere?

These can be married to OMNIBUS with an M8357 RX8-E controller. They sometimes come up on well-known auction sites.

There is a TTL clone of this controller that has been designed by @Roland Huisman. The PCB Gerbers and parts list is available from his website/github repository.

You will get some real disk drive noise with this solution!

Dave
 
Floppy storage is a fairly easy option.

You can build Roland's M8357R:
github.com

GitHub - Roland-Huisman/Digital_RX8E_M8357R: This is a 74xx clone of the Digital RX8E M8357 RX01 / RX02 floppy controller.

This is a 74xx clone of the Digital RX8E M8357 RX01 / RX02 floppy controller. - Roland-Huisman/Digital_RX8E_M8357R
github.com github.com

and Don's RX01/RX02 emulator:
github.com

GitHub - AK6DN/rx02_emulator: DEC PDP-11/PDP-8 RX02 drive emulator

DEC PDP-11/PDP-8 RX02 drive emulator. Contribute to AK6DN/rx02_emulator development by creating an account on GitHub.
github.com github.com
I used Don's documentation and built Roland's 2-layer version of it:
github.com

GitHub - Roland-Huisman/RX01_RX02_Emulator_PCB_2_layer_version: RX01 RX02 Emulator PCB 2 layer version

RX01 RX02 Emulator PCB 2 layer version. Contribute to Roland-Huisman/RX01_RX02_Emulator_PCB_2_layer_version development by creating an account on GitHub.
github.com github.com
Don also has an SMT version of the emulator. Don may have kits available which is probably the easiest path, but not sure about shipping to the UK.

Then when the "real" ones of each of the above become available, replace each of the above with the real thing.

Oh, and an M847-extended-version-v1.1 is extremely helpful too.
github.com

GitHub - Roland-Huisman/M847-extended-version-V1.1: Digital DEC PDP-8/e M847 extended version V1.1 project files

Digital DEC PDP-8/e M847 extended version V1.1 project files - Roland-Huisman/M847-extended-version-V1.1
github.com github.com
(I suspect you'll never want to replace that one. :ROFLMAO: )

I've taken exactly this path. The "real" RX02 is still under my desk waiting to be restored.
I was having much trouble booting from floppy until I used Roland's OS/8 boot loader in the M847-extended...
 
I'll let the group know if I order any PCBs just in case anyone else needs one.
 
gwiley said:
Floppy storage is a fairly easy option.

You can build Roland's M8357R:
github.com

GitHub - Roland-Huisman/Digital_RX8E_M8357R: This is a 74xx clone of the Digital RX8E M8357 RX01 / RX02 floppy controller.

This is a 74xx clone of the Digital RX8E M8357 RX01 / RX02 floppy controller. - Roland-Huisman/Digital_RX8E_M8357R
github.com github.com

and Don's RX01/RX02 emulator:
github.com

GitHub - AK6DN/rx02_emulator: DEC PDP-11/PDP-8 RX02 drive emulator

DEC PDP-11/PDP-8 RX02 drive emulator. Contribute to AK6DN/rx02_emulator development by creating an account on GitHub.
github.com github.com
I used Don's documentation and built Roland's 2-layer version of it:
github.com

GitHub - Roland-Huisman/RX01_RX02_Emulator_PCB_2_layer_version: RX01 RX02 Emulator PCB 2 layer version

RX01 RX02 Emulator PCB 2 layer version. Contribute to Roland-Huisman/RX01_RX02_Emulator_PCB_2_layer_version development by creating an account on GitHub.
github.com github.com
Don also has an SMT version of the emulator. Don may have kits available which is probably the easiest path, but not sure about shipping to the UK.

Then when the "real" ones of each of the above become available, replace each of the above with the real thing.

Oh, and an M847-extended-version-v1.1 is extremely helpful too.
github.com

GitHub - Roland-Huisman/M847-extended-version-V1.1: Digital DEC PDP-8/e M847 extended version V1.1 project files

Digital DEC PDP-8/e M847 extended version V1.1 project files - Roland-Huisman/M847-extended-version-V1.1
github.com github.com
(I suspect you'll never want to replace that one. :ROFLMAO: )

I've taken exactly this path. The "real" RX02 is still under my desk waiting to be restored.
I was having much trouble booting from floppy until I used Roland's OS/8 boot loader in the M847-extended...
Click to expand...
I did get in touch with Don and he was very helpful with the above. Got an order in already.
 
silcreval said:
Thanks - I'll give SerialDisk a go. Do you know which comms cards I can use with a PDP 8/A ? The rack is fairly full although I seem to have one slot free.
Click to expand...
M8650 or M8655.

The M8650 can be modified for faster speeds. The M8655 is limited by the UART to 9600 on some boards and 19200 on others. By default Serial disk uses device codes 40 and 41 so if those are in use by some other card you will need to change that (or rebuild serial disk).

What cards do you have in your 8/a?
 
I'd expect attempting to use a KL8A (M8319) would require a re-write of the Serial Disk device handlers since it is programmed differently than the M8650, M8655 or CESI SLC8 modules.
If you're looking for the fastest Serial Disk you'll want one of the the Omnibus USB modules that are program compatible with the M8650.
Kyle says the Australian one runs Serial Disk reliably at 230.4k baud (similar to RX01 floppy performance).
 
It looks like Roland and Don's card combo might be the way to go. I'll give those a go.
Just FYI the PDP 8/A I have is fitted with a M8317, M8315, ME8316 and what I *think* is a G650 and a G649. So I'm aware the system has 16KW of memory, but from the web it looks like this might be a 16K and 8K core card set?
 
Serial Disk at low baud rates requires patience. A DIR command takes about 20 seconds at 9600 baud. At 19200 the 10 seconds it takes seems blinding fast. 230k baud would be around 0.8 seconds which is still slower than a floppy on a good day.

If I understand you correctly you have a G649 and a G650 in your 8/a. These cards are normally labeled H219A for the 8k and H219B for the 16k. If you have one of each that would be 24k words. And those double boards combined with the three 8/a hex CPU boards you mentioned would use 7 of your 12 slots. assuming it is a short chassis. What else is in there?

I have one of the M8319 (KL8A) four port cards but I have not gotten around to fixing it. Someone was ham handed when handling it and the DIP switch needs replacing as it is shattered. I've not looked to see how much would need to be changed in Serial Disk to work with it.

I have never considered a C interpreter. This stands a good chance of fitting. I was thinking of trying to shoehorn an EM1 interpreter into an 8 and running the ACK (Amsterdam Compiler Kit) but I don't think it will fit on a 32k word (48k byte) machine and be able to compile itself. I have a lot of this fleshed out and the interpreter easily fits on page 0. I am far enough along to tell that it probably will require at least a 64k word 8/a to work and that is a lot less interesting to me. The older versions of ACK were probably developed on PDP-11's. EM1 is a Harvard architecture instruction set with 64k bytes for instructions and 64k bytes for data.,

Another possibility was to modify the Obfuscated C C compiler and change it to generate PAL. If you aren't familiar with this it is a C compiler written in itself that generates i386 code directly. The source for the obfuscated version is about 5k bytes long. This should be possible but it is not really C although it does compile on a C compiler.

Hope you can find a serial card. If that ends up being a problem you can try my console serial disk which runs a serial disk over the console port. I have still not posted this. I am going to do a parallel version that uses the parallel port on the M8316 card at some point. That should end up operating faster than any original mass storage device available for the machines. Maximum plaid for your 8.
 
DougIngraham said:
Serial Disk at low baud rates requires patience. A DIR command takes about 20 seconds at 9600 baud. At 19200 the 10 seconds it takes seems blinding fast. 230k baud would be around 0.8 seconds which is still slower than a floppy on a good day.

If I understand you correctly you have a G649 and a G650 in your 8/a. These cards are normally labeled H219A for the 8k and H219B for the 16k. If you have one of each that would be 24k words. And those double boards combined with the three 8/a hex CPU boards you mentioned would use 7 of your 12 slots. assuming it is a short chassis. What else is in there?

I have one of the M8319 (KL8A) four port cards but I have not gotten around to fixing it. Someone was ham handed when handling it and the DIP switch needs replacing as it is shattered. I've not looked to see how much would need to be changed in Serial Disk to work with it.

I have never considered a C interpreter. This stands a good chance of fitting. I was thinking of trying to shoehorn an EM1 interpreter into an 8 and running the ACK (Amsterdam Compiler Kit) but I don't think it will fit on a 32k word (48k byte) machine and be able to compile itself. I have a lot of this fleshed out and the interpreter easily fits on page 0. I am far enough along to tell that it probably will require at least a 64k word 8/a to work and that is a lot less interesting to me. The older versions of ACK were probably developed on PDP-11's. EM1 is a Harvard architecture instruction set with 64k bytes for instructions and 64k bytes for data.,

Another possibility was to modify the Obfuscated C C compiler and change it to generate PAL. If you aren't familiar with this it is a C compiler written in itself that generates i386 code directly. The source for the obfuscated version is about 5k bytes long. This should be possible but it is not really C although it does compile on a C compiler.

Hope you can find a serial card. If that ends up being a problem you can try my console serial disk which runs a serial disk over the console port. I have still not posted this. I am going to do a parallel version that uses the parallel port on the M8316 card at some point. That should end up operating faster than any original mass storage device available for the machines. Maximum plaid for your 8.
Click to expand...
Thanks Doug. I've created a few interpreters over the years, and they can work quite well. For small machines libraries do so much of the heavy lifting that they are effectively an interpreter anyway. I'm interested in the ALGOL compiler & VM that was developed for the PDP 8 as this seems very optimal and a close fit, so will study that in more detail. I'm familiar with Fabrice's awesome work and thats a good point actually, I hadn't considered that. No rush with any of this of course - part of the fun - in fact most of the fun of vintage computing - is the journey rather than the destination :D
 
ftcnet said:
I'd expect attempting to use a KL8A (M8319) would require a re-write of the Serial Disk device handlers since it is programmed differently than the M8650.
Click to expand...
Knew it existed but never looked at the details. Yup totally different, good to know. I have the CESI board so used to that.
 
You must log in or register to reply here.
Back
Top