Loadstar 247/247.d81/t.tales of Kim 3

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             Tales of KIM
      On the Edge -- Chapter 1.5
           by Brian Bagnell
               Part III


    Rather than try to represent the
scenario graphically, Jim chose to
display the altitude, fuel, and rate
of decent as numbers. Anyone playing
would have to imagine himself huddled
in a capsule with only the instrument
readings to guide him. Four glowing
red LED digits displayed the altitude
and the right two digits represented
the rate of descent.

    Lunar Lander might seem primitive
by today's standards, but back in 1975
board games were the most popular
games available. Snakes and Ladders,
Monopoly, and Checkers were the
pinnacle of gaming, so something like
Lunar Lander was futuristic by
comparison. Lunar

    Lander was a hit at conventions
and gatherings, where it fascinated
hobbyists. Part of the appeal was the
adventure element. Individual landings
could last five minutes or more, so
players could become deeply engaged in
a single game. For a grueling stretch
while the lander descended, a player
would intently study the rate of
decent versus the altitude, and
occasionally glimpse the fuel gauge.
After four minutes, the lander would
be close to the surface, and tension
began to mount. If everything went
just right, the player was rewarded
with a SAFE message.

    More often, fuel ran out and the
module went crashing into the lunar
surface as the dreaded DEAD message
flashed onto the screen. (Lunar Lander
would later spawn a mini-genre of
games around the lunar landing concept
such as Lunar Lander (with graphics),
Thrust, and Space Taxi.)

    Jim Butterfield also created a
small utility called Hypertape, which
had an impact on the KIM-1 user
community. Butterfield was having
lunch with a friend who also owned a
KIM-1, and mentioned that the unusual
circuitry of the KIM-1's cassette tape
input would make it possible to
enhance the speed of tape reading.
"You don't need all those 1's and 0's
written on the tape," he said. The
friend, Julien Dubi, asked how that
could be accomplished and Jim outlined
his approach.

    The next day, Julien reported a
speedup of three times. Feeling that
this was a challenge, Jim looked more
closely at the code, and found extra
ways to accelerate the format. The
final version of the program allowed
data to be written six times faster. A
full one-kilobyte program now only
took 20 seconds to load with the
standard KIM-1 system, as opposed to
the regular two minutes.

    In July 1976, the first issue of
Kim-1 User Notes appeared, with Eric
Rehnke as editor and contributions
from Butterfield. Jim eventually
amassed enough information to release
a book. He teamed up with Rehnke and
Stan Ockers to self publish a 176-page
opus called The First Book of KIM.
This was one of the pioneering works
in what would later become a lucrative
computer-publishing business.

    Several key areas of the KIM-1
were explained which could not be
found elsewhere, such as programming
the LED display to output custom
characters and using the timers built
into the 6530 chips. The book was also
a software treasure trove, containing
carefully commented listings for the
most popular KIM-1 programs. The book
gained a reputation as being
indispensable for KIM-1 users and
programmers.

    One of the contributors to The
First Book of KIM was Peter Jennings
(not to be confused with the news
anchor), another Toronto resident.
Jennings had just graduated university
and he was anxious to purchase his own
computer system. Cost was a major
factor in his decision because of
outstanding student loans. He knew
from articles in magazines that the
Altair used an 8080 chip and the KIM-1
used a 6502 chip. Jennings wanted to
test drive his new computer before
buying, but microcomputer users were
hard to find.

    "We take for granted how easy it
is to track down people with common
interests these days with Google,"
says Jennings. "The only group of
computer enthusiasts in Toronto at the
time was 100% 8080."

    To weigh the merits of each chip,
Jennings, who worked for a company
called Comshare and had access to a
Xerox Sigma IX time-sharing computer,
developed a set of emulators modeling
the 8080 and 6502 chips. When Jennings
finished his comparison, it was no
contest. He wanted to program the
6502.

    In May 1976, Jennings made a small
journey to the Midwest Regional
Computer Conference in Cleveland,
Ohio, just four hours from Toronto.
There he paid $245 for his KIM-1 and
happily drove back across the border
to begin a much longer journey.

    Peter Jennings contributed a
simple game to The First Book of Kim,
but he wanted to try something more
challenging. He chose the game of
kings, chess. Chess programs are
notorious for using large amounts of
memory. The program must create copies
of the chessboard and then evaluate
each board. Most sane people scoffed
at the idea of creating a chess-
playing program in one kilobyte of
memory.

    To put one-kilobyte of memory in
perspective, imagine a display of 40
characters by 25 lines - 1000
characters on a single screen. That is
just about one-kilobyte. Jennings'
task was like setting a table for 12
people on a stool. If he had thought
about it a little more, he probably
never would have started. "Most
computer programmers thought it was
impossible," remarks Jennings.

    In order for the computer to move
a chess piece, it must be able to
identify all legal chess moves at any
given time. This is a tall order with
just one kilobyte of memory,
considering there are six different
chess pieces that all make unique
moves. Furthermore, some moves are
illegal when the king is under attack.
Jennings' program had to test all
these conditions. If Jennings' game
merely made a random legal move, it
would have been sufficiently
impressive. Peter wanted more. He
wanted the computer to think and
scheme.

    Not only was memory space against
him, but his tools were absurdly
primitive. Programming the game would
be difficult even with a powerful
computer connected to a keyboard and
video display but Jennings had only
the KIM-1 to develop his masterpiece -
a small calculator keypad and
six-digit display, connected to a
teletype machine for hard copy.

    Still, he used what was available
to him, even including extra
functions. "Peter found room for
diagnostics," marvels Jim Butterfield.
"For example, the display would
flicker with data during the strategy
part of the run, and he could read
what it was up to - 'It's checking
Queen mobility now...'" For months,
Jennings toiled away at his impossible
task. Sometimes he was a willing
insomniac, gloriously coding until
sunrise with (and sometimes against)
his KIM-1.

    Those who looked in on him thought
he was performing deep calculations
with a large calculator, oblivious
that he was actually teaching a
computer to think about chess. Six
months later, Jennings prevailed in
his battle against the kilobyte.
Microchess used 1118 of the available
1152 bytes of memory in the KIM-1.

    "It was quite a squeeze," says
Butterfield. "He even made use of the
small RAM areas within the 6530 chips.
I found it an amazing accomplishment."
It is easy to be impressed by large
projects, but more difficult to
appreciate something small. Jennings
program was smaller than any piece of
software written today, yet the
compactness and efficiency made it
impressive. His accomplishment must
rank as one of the most incredible
programming feats of all time.

    "Jennings had accomplished
something that, if asked, I might have
dismissed as impossible to do in that
small computer," says Butterfield.

    Engineer Robert Yannes credits
some of Jennings success to the 6502
itself: "The 6502 was a very efficient
processor for its day." In many ways,
Jennings achievement was lonely.
Everyone can appreciate a baseball
knocked over the outfield fence, but
it was a rare person who could
understand this achievement. But Jim
Butterfield and the cadre of
programmers around him knew what it
meant.

    "Peter demonstrated his program at
a small gathering of KIM-1 users in my
home," recalls Butterfield. "I had set
up a chessboard marked with the
coordinates to match the KIM's displ