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What's this?… |  |
It's a fragment of 6502 assembly code. I spent a lot of time programming in
6502 on my first personal computer, an Acorn Electron. This excerpt is from one of the many
versions of
Life
I've written.
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We've already added the number of living cells around this one, and the
sum is in the A register.
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TAY
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We transfer A to Y (TAY)
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LDA liveRule, Y
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We load A (LDA) with the appropriate rule value, using Y as an index.
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BEQ cell_dies
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Then we branch to the appropriate code if the value is equal to zero (BEQ);
the rule says the cell must die.
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I have lovingly re-created the Electron's font from Appendix F of the User Guide.
Actually, I wrote a small Windows program with the font coded into it as an array of
bytes representing each character's bit-pattern (laboriously hand-entered from a faxed copy
of the manual -- thanks for the fax, Dad). The program rendered strings using the font,
so I could build my little assembler fragment image:
.