

The Origin of Spacewar! (1981) - masswerk
http://www.masswerk.at/spacewar/SpacewarOrigin.html

======
jf
If you want to play Spacewar on a real PDP-1, the Computer History Museum in
Mountain View has a restored PDP-1 with Spacewar on it:
[http://pdp-1.computerhistory.org/pdp-1/](http://pdp-1.computerhistory.org/pdp-1/)

Steve Russell works at the museum these days, so you might even run into him
if your timing is right!

~~~
masswerk
The next best thing (but without Steve Russell himself, sorry) can be found
here: [http://www.masswerk.at/spacewar](http://www.masswerk.at/spacewar) (a
JS-emulation of a PDP-1 running various versions of Spacewar! – the version
closest to the program described in the article is "Spacewar 2B", but the
version seen in the photos is probably a bit later and more advanced.)

But of course we ought to visit the CHM, in case we would have a chance to do
so.

------
codezero
It's pretty amazing that the display had 1024x1024 and up to 4096x4096
resolution on 5 inch screens in the 60s.

They say the 4096x4096 was for photographic recordings, I wonder if there is
any data saved that was displayed at this resolution from the 60s, it seems
like each photo would have been huge compared to the size of storage available
back then.

~~~
masswerk
It's really hard to say, but some of the high-res scans of DEC promotional
material for the Type 30 CRT (1024 x 1024) at bitsavers.org are showing
screenshots with a pretty good quality:
[http://bitsavers.org/pdf/dec/pdp1/JPEGs/](http://bitsavers.org/pdf/dec/pdp1/JPEGs/)

On the other hand the 1024 x 1024 of the standard display was rather a
technical resolution, the visual resolution would have been – according to DEC
– about the half (since the bleeding phosphor of the activated blips on the
screen would overlap and merge). A closeup of the Type 30 CRT displaying an
early version of Spacewar! can be seen here:
[http://www.masswerk.at/spacewar/decus1962/spacewar-
decus1962...](http://www.masswerk.at/spacewar/decus1962/spacewar-
decus1962-figure1-large.jpg)

On the storage capacity: Please mind that these weren't bitmap driven
displays, all the images had to be composed and refreshed algorithmically. On
the up-side, this meant that even a small program could display effective
graphics, like Snowflake (see:
[http://www.youtube.com/watch?v=Y1ioLo2I_5Y](http://www.youtube.com/watch?v=Y1ioLo2I_5Y))
which would only use about 190 instructions or memory locations. Also,
consider that these were 18-bit words holding op-codes (6-bit) and addresses
(12-bit) in the same instruction word. This was quite more densely packed,
like say, in a 8-bit microprocessor computer. For example, I would doubt that
(the original) Spacewar! could have been ported to a C64, both for speed and
storage, left aside the graphics. (But I could be proven wrong here ... :-))

~~~
swimfar
The screenshots are here (so you don't have to click all 25 images looking for
them):

[http://bitsavers.trailing-
edge.com/pdf/dec/pdp1/JPEGs/Type30...](http://bitsavers.trailing-
edge.com/pdf/dec/pdp1/JPEGs/Type30CRT_Jun64_3.jpg)

[http://bitsavers.trailing-
edge.com/pdf/dec/pdp1/JPEGs/Type30...](http://bitsavers.trailing-
edge.com/pdf/dec/pdp1/JPEGs/Type30CRT_Jun64_4.jpg)

~~~
masswerk
A display similar to the Type 30 CRT can be seen in action in this video of a
Bell-Labs educational film:
[http://www.youtube.com/watch?v=iwVu2BWLZqA](http://www.youtube.com/watch?v=iwVu2BWLZqA)
("The Incredible Machine", 1968).

The video shows later equipment, a PDP-5 and a display that looks like a
member of the 330/340-family, but the technology is the same. (Interactive
graphics technology like in TX-2 and the PDPs was actually amazing, but
apparently got lost over time-sharing ...)

