So you've built a PiDP-11, now what? Here are some things I've learned.

When you first boot the PiDP-11 you will see the following:

PiDP-11/70 boot menu - Set SR switches, depress address rotary switch to reboot


0000    idled           0102    211bsd          0115    sysv

0001    rsx11mplus      0105    unix5           1000    nankervis

0002    rsts7           0106    unix6           1001    idled

0003    rt11            0107    unix7           1002    blinky

0004    dos11           0113    sysiii


Now running IDLED - set SR0-7 for desired front panel patterns


What these are showing your are the octal codes you can enter with the switches to enter into these various OS or modes. By default the PiDP-11 enters the "idled" mode or 0000. If I'm not doing anything with my PiDP-11, then I like to have it running in "blinky" or 1002. How do you do that? 

For beginner start with the rightmost set of 3 switches. In octal notation they have the value from right to left of 1, 2 and 4. So below you can see how you can create any number from 0 to 7 by setting the switches accordingly. So in the case of blinky lights, you set the rightmost set of three to 2, the next two octal sets remain at 0, and then the fourth set will be set to 1. 

So really the first thing you need to do is push Stop. Then Add the mode you've set to the register. Then push the top, right button. The device will now go into "blinky" mode. 


Best games seem to be in the RT11 OS. So let's get there by setting the swithes to 0003 and booting into RT11.

Some games or applications, which have visual components, have to be played in an RT11 terminal. The only way to get to that terminal (as far as I know) is through the Gnome GUI, so you either have to connect a monitor to the PI or set up some remote desktop protocol like VNC.

When you enter into RT11 a VR14 CRT display will appear.

Let's do a DIR *.SAV to see what apps can be run in the linux terminal. For example Lunar Lander can be run by typing: R RTLEM.SAV

(NB. took me a while to figure out that in order to control the lander you have to click on the various options to the right of the screen)

When you're done playing it seems the only way to get back to RT11 is by rebooting into RT11 manually.

Some other games are found by typing DIR *.BAS or DIR *.GT. These are basic games and are started by typing:



STAR.BAS   [or whatever file]


To play some other games, after booting into RT11 type CTRL+E. Then:

detach rl1

attach rl1 rt11games.rl2


Now type: DIR DK1:*.SAV

In order to run one of these games, type: RUN DK1:SPCINV 

You have to have a proper VT-52 terminal to play some of these games. 

There are also some VT animations: DIR DK1:*.VT

To activate these type: TYPE DK1:CASTLE.VT

Some of these require a specific terminal size.

Final note: some of these files are best operated in the VR14 display. You can switch to that display by typing GT ON. Of course, GT OFF will get you out of it.