PDP-1

Programmed Data Processor-1

A PDP-1 emulator is a curiosity I had for a while at the back of my mind: having read about the original 1962 Spacewar!, the Minskytron ‘display hack’ and in general about the history and technology of the PDP-1 I wanted to learn about it hands-on and thereby see these outputs on the Vectrex, too. The CCPU Vectorbeam/Cinematronics hardware over a decade later was specifically built to play Spacewar after all and spawned a multitude of vector games, just to name one impact this first cpu-based computer game had. Another would be Asteroids, which besides some design decisions inherited the inputs – the exact same 5 buttons including the ‘might kill you’ precarious hyperspace setup.

Like the later, discrete CCPU by Vectorbeam the PDP-1 is not ‘byte’ based, something everyone today takes for granted as a basic building block of computer science, but nibble based – 4 bits. Plus uses octal and not hexadecimal to program and describe the hardware, something which stopped being used in the 1970s where you can still see it pop up in rare cases (the register documentation for the AY891x chip for example is in octal for whatever bizarre reason). Interestingly the C language does support octal, something I was not aware of anymore since I never needed it, which was convenient here.

One nice thing for the PDP-1 is the amount of information you can find online -original, archival efforts, hobbyists- and among others I found a price list for a PDP-1D in 1963 – an entry level ‘minimum system’ (which runs Spacewar) would have set you back $138k, or $1.2M in current dollar value. Not including the engineer(s) you’d had to employ to actually use this Bronze Age computer to play Spacewar!…

Input

The Spacewar! tape uses the four buttons of both controllers for left/right/thrust/fire and all four buttons pressed for hyperspace, just like the original Spacewar! which also uses only 4 separate buttons and ‘all 4’ for hyperspace.

The Minskytron uses button 4: to cycle through several, nice looking setups for the PDP-1 switches resulting in different, nice visual output.

Options

• Tape: Spacewar/Minskytron
• Info: ”                           Tiny PDP-1 Emulator using the adapted Spacewar (the one with larger ships) and in general custom display functionality to be able to output on a vector display.                      “

Localization

//NAME="PDP1"
//
GERMAN[] = {
    { 0, 0, "Band: Spacewar"},
    { 0, 0, "Band: Minskytron"},
    { 0, 0, "                           Kleiner PDP-1 Emulator mit angepasstem Spacewar (mit grösseren Schiffen) und spezieller Grafiknachbearbeitung, um die Ausgabe für ein analoges Vektordisplay zu verbessern.                      "}
};
FRENCH[] = {
    { 0, 0, "Bande: Spacewar"},
    { 0, 0, "Bande: Minskytron"},
    { 0, 0, "                           Petit émulateur PDP-1 présentant un jeu Spacewar sur mesure (à savoir celui avec de plus grands vaisseaux spatiaux) et disposant, de manière générale, d'une fonctionnalité d'affichage personnalisée pour pouvoir sortir le signal sur un moniteur vectoriel.                      "}
};
ENGLISH[] = {
    { 0, 0, "Tape: Spacewar"},
    { 0, 0, "Tape: Minskytron"},
    { 0, 0, "                           Tiny PDP-1 Emulator using the adapted Spacewar (the one with larger ships) and in general custom display functionality to be able to output on a vector display.                      "}
};