888888
000000
| ns |
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ll/34 is a cycle-accurate, circuit-level emulator for the PDP-11/34A (1976). It runs the original ROM tables, either dumped or reconstructed from the schematics, and is essentially a direct translation of the KD11-EA engineering drawings.
Read more at https://github.com/dbrll/ll-34
Damien Boureille, 2026. MIT License
Fun facts:
- The power switch on the front panel is silent. The loud clicking sound comes from the relay in the PSU.
- The CPU is cooled by two large AC fans running at mains voltage. They are about as loud as a vacuum cleaner.
- The KD11-EA CPU uses a remarkably simple design. It is roughly a third of the complexity of an Intel 8086 in transistor count, yet achieves comparable performance. Just 512 words of microcode control the CPU, and open-collector ROMs combine their outputs by wire-OR to decode instructions without arbitration logic.
ODT (Online Debugging Tool) is the console monitor built into the M9301-YF boot ROM (what would be called a BIOS or EFI nowadays). It allows loading, running, and debugging code from the terminal.
ODT consists of four commands:
L XXXXXX Load address (in octal)
ODT uses the "space" key instead of "Enter".
E Examine word at current
address (auto-increments)
D XXXXXX Deposit word at
current address (auto-increments)
S Start execution at current
address
Example:
L 1000 [space], then E to read address 001000.
Type D 777, then [space] to write 000777 there.
Finally, S [space] to start execution from that address.
Note: ODT may seem spartan, but the only memory it requires to run is the CPU registers!
A small Transformer (1216 parameters) for the PDP-11/34, written in baremetal assembly. Training takes about 5:30mn. Read more at github.com/dbrll/ATTN-11/
Conway’s Game of Life, loaded from an ASCII object file. Runs continuously in the console.
RT-11 SJ V04, Digital’s single-job
real-time operating system. Boots from a virtual
RK05 disk. It uses TOPS-10 commands, like OS-8,
CP/M or MS-DOS:
cd, dir,
type. Run a program with
RUN followed by the program name.
Programs use a SAV extension.
The disk image includes the original
Tetris game written for the
Elektronika 60, a soviet PDP-11/03 clone. Type
RUN TETRIS to play. Controls:
7/9 left/right,
8 rotate, 4 speed up,
5 drop.
Note: the game runs roughly 2× faster than intended since the PDP-11/34 is faster than the original target machine.
Sixth Edition UNIX (1975), the first version of UNIX to be widely distributed outside Bell Labs.
Type rkunix at the RK05 disk drive bootloader (@ prompt).
Log in as ken or root (no
password). On V6, cd is
chdir, and SIGINT uses
DEL instead of ^C.
A small neural-network written in Fortran IV under RT-11 V3. It uses backpropagation to train a multilayer perceptron on the XOR problem.