Hardware Reference
In-Depth Information
A VERSION OF
Ping-Pong, or table tennis, was one of the early electronic games; it was irst
produced by Willy Higginbotham in 1958 and used an oscilloscope as a display. his was long
before the advent of microcomputers. You could make a version of the game by using just
logic gates, with no processors involved. I made one back in 1970 that generated its own TV
signal. It was, by today's standards, a weird hybrid of an analogue and digital circuit - with
the path of the ball being driven by two analogue integrators, and those voltages triggering
comparators against an analogue sawtooth TV time base. By 1975 all the logic had been com-
bined into one chip, the AY-3-8500, making it a much easier circuit to build. It even had a
choice of games which were simple variants on the same theme. his chip appeared in hun-
dreds of products and was the irst low-cost home TV console. I even built a console using
this chip as well. A few years after that, home microcomputer systems came along, and table
tennis was one of the irst graphics games to be implemented.
Early Commercial Products
On the commercial side, the Magnavox Odyssey, designed by Ralph Baer, was the irst game
console to go on sale to the general public. his was irst demonstrated in 1968, but was not
commercially available until 1972. It was seen before its launch by Nolan Bushnell, who
cofounded Atari, so he assigned the newly appointed engineer Allan Alcorn to implement the
game as a training exercise. he results were so impressive that Bushnell decided to launch it
as an video arcade game using the name
Pong.
his name sounded odd to U.K. ears, as it is a
slang word for a very bad smell. Just a few days into the testing of the irst prototype in a bar,
the owner rang up to say that the game had stopped working. On investigation they found
that the money had backed up and jammed the mechanism. So the irst upgrade was to it a
bigger coin box - something Bushnell later said he was “happy to live with”. Inevitably
Magnavox and Atari ended up in court, but out-of-court settlements were reached. Pong
then went on to be released as a home TV console.
So the game has a honored place in the history of computing and serves as an interesting
introduction into arcade type games on the Raspberry Pi. You might think that being a game
from the early days of computing it will be simple, and it is, but it is not as simple as you
might hope. he early games were written in Assembler language; with today's computing
power you can write a table tennis game in a high-level language like Python.
The Ping Game
Basically, what I am calling
Ping
is a copy of the bat-and-ball game which spawned a whole genera-
tion of computer games. What you are going to implement here are two games, a one-player game
and a two-player game. Figure 5-1 shows the screen display of the two-player game, but they look
very similar. As with all projects, it is best to start implementing features one at a time and build-
ing up the sophistication and complication as you go. However, irst you need a bit of theory.
