Re: Apple and the Holy War

[Paul Guertin <pg@sff.net>]

pausch@saafNOSPAM.se (Paul Schlyter) wrote:

> > other's. But Paul, one of the early programs written on the DEC PDP -1 at
> > MIT was a program called "Expensive Typewriter" the first known word
> > processor. In the late 1950s.
>  
> BTW I believed at that time the very first computer games were also
> created.

PDP-1 Spacewar (early 1960s) is considered by many to be the first video
game. You use a joystick to maneuver a spaceship and try to shoot the
other player down. See http://www.wheels.org/spacewar/index.html and
http://www.enteract.com/~enf/lore/spacewar/spacewar.html for screen shots
and information. You can play Spacewar in a Java PDP-1 emulator at
http://kame.media.mit.edu/groups/el/Projects/spacewar/ . Have fun!

Everyone interested in the early days of computing (from the mainframe
hackers to the video game boom of the 80s) should read the book "Hackers:
Heroes of the Computer Revolution" by Steven Levy (see
http://www.stevenlevy.com/hackers.html ).

> The CDC 6600 had a quite odd archtecture: it was word-addressed and
> had 60-bit words.  Addresses were 18-bits, which means it could
> address 256 Kwords (which approximately corresponds to some 2
> MBytes).  It had no hardware stack, which made recursive functions
> quite hard to implement.  The standard approach was to reserve the
> first word of each function for the return address: the caller would
> then store its return address there and then start executing code at
> the next word - when returning, an indirect jump was made to that
> first word. 

I believe this is also how the RCA 1802 microprocessor does it -- if
you need recursion or reentrancy, just implement a stack in software.
The 1802 is a cute and minimalist processor that should appeal to many
6502 enthusiasts.

Paul Guertin
pg@sff.net