Supporting the Pi 4

A project log for PiDP-11

Replicating the PDP-11/70

OscarvOscarv 08/19/2019 at 19:490 Comments

I just updated the firmware to support the new Pi 4, which has a slightly different way of enabling the internal pull-up resistors on the GPIO.

So... where the Pi 3B+ was 6 times faster than the real 11/70 at 7241 dhrystones/second, versus 1250 for the 1975 original... you can now enjoy a 12x speed boost versus 1975. For those who like to be as authentic as possible, use a Pi 2! Or use the 'set throttle' configuration to slow down the Pi 4. Or run multiple 11/70s in parallel. At least the Pi 4 shows there's still progress in computing and 2.11BSD unix feels like lightning :)

The other nice thing of the Pi 4 is that you can use one HDMI display for a faithful CRT display (using cool-retro-term) and a second one for the very cool Tektronixvector tube simulation, which really uses the 4K resolution of the Pi 4: