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Ultimate PDP-8 ideas thread

re: Omnibus projects:
  • TD8E controller clone
I vote No on this one, it's not worth the effort. Charlie Lasner explains it best, but

... note that DEC did implement a TC8E Omnibus DECtape controller to the prototype stage, but never sold it. It was totally compatible with the TC01/08 ...

Yes, the TC8E documentation has probably been lost, but I'd certainly be interested in purchasing a couple TC8E Omnibus DECtape controller's if they could be re-created somehow.
 
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antiquekid3 said:
I have been discussing many projects with various people lately, and thought it would be a good idea to get these out to everyone to "vote" on them and express interest to help myself and others prioritize. I will also touch on projects already completed by others for added visibility.

Without further ado...

Omnibus projects:
  • Bus analyzer card to easily probe the backplane with a logic analyzer
  • PDP-8/A MMU for 128kW
  • "The Ultimate" block device, featuring single-cycle data break, SD card storage, 4095 blocks per device, zero seek time, etc.
  • CPLD CPU set
  • CPLD EAE set
  • TD8E controller clone
  • TU10 controller clone
  • RL01/02 controller clone
  • Punched card reader controller clone
  • Paper tape punch/reader controller clone
  • VGA graphics board (possibly emulating a storage 'scope, supporting bitmapped and vector graphics)
  • Programmable real time clock
  • Posibus converter plus multi-data break board
  • Multi serial/SPI/422/485/MIDI interface board
  • Massive parallel I/O card
  • Sound card and general DAC/ADC board
  • LAB-8/E boards and peripherals
  • LINC/TC12/VC12 coprocessors
Many people want more Omnibus boards. Roland has already done a great job providing perfect copies, including the TA8E controller and the RX8E controller, the latter of which can be used with Don's RX emulator. We already have fast serial boards thanks to Philipp's Omni-USB serial board and other CPLD-based solutions, too. Bootloader, memory, and even the VC8E are all taken care of thanks to the efforts of many, including Roland, Vince, and originally, Steve Lafferty for the memory.

Posibus projects:
  • Expansion chassis (allowing small, pluggable modules, smaller than an Omnibus board)
  • TTY interface (Vince has nearly completed this one)
  • VC8I (point plot display controller)
  • KV8I (vector display controller)
  • TC08 (intelligent DECtape controller)
  • DW8E (for connecting to many Omnibus peripherals)
  • DM04 (data break multiplexer)
  • DF32/RF08 controllers and emulators
  • Negative to positive logic converter
We don't want to leave out people with Negibus/Posibus machines, so having some Posibus peripherals would be useful. These of course can be used with Omnibus machines with the appropriate Posibus converter board. The VC8I and KV8I options could be cloned as they are for an 8/I backplane, as well reformatting them onto a single board for the Posibus expansion chassis. David has already created a working DF32 emulator, but controllers are hard to find. Probably not as hard as finding a working DF32, though...

Schematic projects:
  • Digitize PDP-12 schematics
  • Digitize FPP-12 schematics
  • Digitize FPP-8/A schematics
Vince has already done an incredible job digitizing numerous schematics, including the complete PDP-8/I print set, among many others. Here's the print set for the 8/I: https://svn.so-much-stuff.com/svn/trunk/Eagle/projects/DEC/PDP8I/pdp8i-decSCH.pdf This obviously has many benefits over the original, including readability, text searchability, and the ability to export a netlist and turn it into a Verilog PDP-8/I. The same could be done for the PDP-12 and others, once their schematics are drawn.

Simulation projects:
  • SimH LINC/LINC-8/PDP-12
  • Verilog PDP-12
  • Verilog PDP-8/E
Vince, yet again, has been working on modifying SimH's PDP-8 simulator to support the related LINC machines. He's made tremendous progress so far, but it's difficult when so much of those computers were dependent on the peripherals, which can be difficult to simulate.

Other projects:
  • FPGA PDP-12 (would be particularly fun given the number of cool peripherals)
  • FPGA PDP-8/I
  • FPGA PDP-8/E
  • PLL board for an RK05 to use 12 sector packs in place of a 16 sector one
  • Cataloging all PDP-8 software using SHA signatures, keeping track of metadata, etc.
  • A proper vi clone text editor
  • A comprehensive, all-in-one device dump and restore utility with additional error reporting, based upon David's dumprest utilities
A lot of fun could be had with FPGA clones of these computers, since they could even connect to real peripherals and such, given the appropriate bus interfacing. A PLL board replacement in an RK05 allows us to use PDP-11 packs as if they were PDP-8 packs, so long as they are reformatted.

I'd love feedback on any and all of these ideas, and I suspect some new threads will grow out of this one to discuss specific projects.
Click to expand...
I think I can help with some schematics.
Please consult my site: www.vandermark.ch/pdp8/index.php
 
The TD8E, PC8E and DR8E were on my to-clone-in-TTL list. I've made a start with a EAE TTL clone, but a new job and other stuff put a halt on all my clone projects. The PC8E controller would be simple to clone in TTL. I must have a spare somewhere, that would help cloning that one a bit faster.

The RK8E would be fun too, but cloning a three board set in TTL would get a bit costly and a huge amount of work... So an cpld or fpga alternative would be nice here.

ftcnet said:
Click to expand...
I've seen Charlie's story too, but still... Why voting no on the TD8E? It is fun to use a TD8E with a TU56 and it works fine for years over here. And most important, there is no simple alternative. If I had another TU56 I would make a TTL clone of my TD8E immediately. And a single TTL board is not too expensive compared to the amount of fun you can have with it :biggrin:


It would be nice if we know who is making what to prevent that people are working on the same project without knowing this from each other. (See RK05 emulator/tester project for example) And I think it is good to make a priority list of all the devices. Is there a way to make a poll in VCFED?

My list of tested PDP8 clone boards:
TA8E M8331 TU60 tape controller
RX8E M8357 RX01/RX02 controller
M847 extended version bootstraploader
H851 top connector PCB
DK8E M822 mains RTC
VC8E M869 point plot controller
VC8E M885 digital to analog converter
VC8E to Tektronix or XYZ monitor Interface
SpaceWar! modified to run without EAE on VC8E / DK8E
H851 debug cable


Regards, Roland
 
Roland Huisman said:
I've seen Charlie's story too, but still... Why voting no on the TD8E? It is fun to use a TD8E with a TU56 and it works fine for years over here. And most important, there is no simple alternative.
Click to expand...
If DEC was able to make a TC8E (Omnibus TC01/TC08) decades ago (with the TTL chips available then), it /should/ be possible to re-create a TC8E with todays technology. One advantage of resurrecting a TC8E would be the ability for Omnibus machines to use/run software written to work with the old negi/posi-bus controllers.
I have a TD8E/TU56 in my 8E and you're right, it does seem to be adequately reliable when used with OS/8, but when I run the DEC X/8 excerciser, enabling the DECtape module just kills the overall system performance.
It just seems (to me) that time spent with KiCAD laying out a board would be better spent working on recreating a TC8E controller, but the ability to produce new TD8E's would also be a 'good thing'.
 
ftcnet said:
re: Omnibus projects:
  • CPLD CPU set
Simulation projects:
  • Verilog PDP-8/E
Before you spend a lot of time on these, you might find these of some interest:
Click to expand...
Good finds. I am particularly fond of as-authentic-as-possible for HDL simulations, particularly when it comes to timing. My 8/I implementation is not currently passing diagnostics after upgrading my version of Verilator, so that's interesting. I'm still looking into that, but would like to accurately capture the 8/E CPU and EAE boards to implement them in CPLDs, with the idea of any single board could be replaced as needed with the CPLD equivalent, but the boards could support multiple CPLDs to potentially reduce the board count by several for someone that doesn't have any CPU or EAE boards.

ftcnet said:
re: Omnibus projects:
  • TD8E controller clone
I vote No on this one, it's not worth the effort. Charlie Lasner explains it best, but

... note that DEC did implement a TC8E Omnibus DECtape controller to the prototype stage, but never sold it. It was totally compatible with the TC01/08 ...

Yes, the TC8E documentation has probably been lost, but I'd certainly be interested in purchasing a couple TC8E Omnibus DECtape controller's if they could be re-created somehow.
Click to expand...
The TD8E is too simple not to go ahead and clone. It would not stop me from also making a TC08 and perhaps a TC8E as well. Of course, a blinkenlight panel would basically be required for the former, and though it could be added for the latter, I'm not sure how it would be mounted...

wim said:
I think I can help with some schematics.
Please consult my site: www.vandermark.ch/pdp8/index.php
Click to expand...
Thank you! I will certainly check it out.
 
I am working on a "Debug" board for the Omnibus. This board would be something like the Unibone but more oriented towards programming. Eventually with hardware breakpoints even. Back in the early days debugging system required a small piece of software running on the target system. My goal is to implement the debugger with only a 2 or 3 word foot print on the target. Less if I can capture the MA and EMA busses when a halt instruction is encountered.

Any help on designing the single cycle data break circuit and other circuits would be greatly appreciated.
 
BitWiz said:
I am working on a "Debug" board for the Omnibus. This board would be something like the Unibone but more oriented towards programming. Eventually with hardware breakpoints even. Back in the early days debugging system required a small piece of software running on the target system. My goal is to implement the debugger with only a 2 or 3 word foot print on the target. Less if I can capture the MA and EMA busses when a halt instruction is encountered.
Click to expand...
What you're describing is sort of similar to the DEC KC8-HA (M8355) and KC8-HB (M8356) Omnibus options.
The KC8-HA included a standard-size front-panel display mounted above the 8/E that showed all the major registors and status bits -no need for the rotary selector switch.
 
So many great topics here.

Very high on my wishlist is a serial card. Or better multiserial card. Because I like to have os8diskserver ready on all of my 8's (for maindecs and central software distribution). Together with more than one terminal connected (multiuser or TEK-grafic) I need a lot of serial connections. Meanwhile I have 10 minis, so I'm short with serial cards.... And I would like to integrate more serial components (papertape, switchboxes and more).

Next would be VC8E.
 
gnupublic said:
Next would be VC8E.
Click to expand...

The VC8E has already been beautifully done by Roland Huisman:

github.com

GitHub - Roland-Huisman/Digital_VC8E_M869R_Point_Plot_Controller: Digital VC8E M869R Point Plot Controller

Digital VC8E M869R Point Plot Controller. Contribute to Roland-Huisman/Digital_VC8E_M869R_Point_Plot_Controller development by creating an account on GitHub.
github.com github.com
github.com

GitHub - Roland-Huisman/Digital_VC8E_M885R_Digital_Analog_converter: Digital VC8E M885R Digital Analog converter

Digital VC8E M885R Digital Analog converter. Contribute to Roland-Huisman/Digital_VC8E_M885R_Digital_Analog_converter development by creating an account on GitHub.
github.com github.com

I built it and it works perfectly.
 
Kyle,

Good to see you ‘stirring the pot’ on this. I tend to also favor an FPGA approach, as CPLD’s seem to be fading away.

My thought is a combination board that could be used to supplement or rescue a PDP/8 (E, A, M). Sorry for the Omnibus focus, but there might be trickledown benefit to other 8’s.

This combo board would be able to supply memory, block storage, serial, etc. to get an Omnibus up to running OS/8. If it included the CPU set (perhaps with EAE), it would literally be a one-board system. It could also have debug lights/port or status onboard. For rescue and supplement, it would be able to turn on and off each capability in order to work with real memory, real peripheral boards, etc.

This might be out of scope with what you were thinking, but having a multi-use board would help a lot of folks, IMO.

-Crawford
 
I've been thinking seriously about an Omnibus module tester... kind of a cousin of the Stearns Flip Chip tester. It would be a bit more challenging to develop test vectors for the more complex boards though.
 
gwiley said:
I've been thinking seriously about an Omnibus module tester... It would be a bit more challenging to develop test vectors for the more complex boards though.
Click to expand...
True, the need for some Omnibus option ECO's only became apparent when installed in a 'fully loaded' (60-80 slot) configurations.

In Remo Vogelsang's memoirs, (Functional Perceptions) he writes "In fact a bus participant was able to run the machine in "phantom" mode, autonomously forcing instructions." I can't think of any known Omnibus option that made use of that capability, but does it seem like something an Omnibone would make use of?
 
A friend is modifying the firmware of the Atmel of the 32k RAM/Bootloader card from Vince/Roland.
He made a minimal terminal session to the Atmel that lets you interactive work with the Omnibus. This might be helpful for repairing cards in the Omnibus.
Once this is tested he will show it here. This might be helpful, because it is easy to update and there is an amount of this cards in use.

I've heard that the raspberry microcontroller would be able to work with 5V TTL, but this is not official specs. Maybe this is an cheap and easy to use device for toolings.
 
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