PDP-1 in Verilog (Incomplete) + More

Jan Adelsbach jan at janadelsbach.com
Thu Jul 30 14:32:29 CDT 2015

Hi all,

At the time I've released my DG NOVA in Verilog I was also working on a 
PDP-1 in Verilog. Since I haven't
touched the thing for quite some time I've decided to just release it 
before it catches dust. So far it can
execute all kinds of programs, limitation is that they may not use IO as 
I haven't implemented the latter yet. (So essentially the same state as 
my DG NOVA implementation)
It also supports optionally some PDP-1D features in the OPR and SKP 
instruction groups. Interrupts are implemented but untested. I'm not 
sure in which state I left the IOT controller if it works then both SBS 
and SBS16 might be usable.
TL;DR: https://github.com/Jside/pdp1

The RCA110 was the project I was working on before I started the DG 
NOVA, it can execute some instructions but there is to much ambiguity in 
the reference manual on bitsavers in some cases which led
me to abandon it. Especially since there is no software to cross-check. 
So for reference you can get it here:

I wanted to mess around a bit with Chisel (a new HDL language used by 
the RISCV project) so here
is the start of a CDC160 (currently only the instruction decoder): 

I've also uploaded my DG NOVA to Github: https://github.com/Jside/nova1

MC14500B anyone? http://janadelsbach.com/soft/mc14500b.tar

I will occasionally continue working on both the NOVA and PDP-1 (and 
maybe CDC160?). Also pull requests are welcome.
As is obvious I *really* like implementing old computers in HDL 
languages but I always get stuck
around IO since for any kind of flexibility as with an emulator I 
essentially would need to write a bus wrapper so that a (soft-core) 
processor executing Linux running an IO server could handle i.e. hard 
disks and magnetic tapes and that's I think really not worth it. So I 
might just go over and contribute to an emulator/simulator like SIMH if 
I'm in an must-implement-an-old-computer/processor mood ;).


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