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collapseos/blk/205
Virgil Dupras 0f2d14ad8a z80a: add BREAK, instruction
This allows us to remove a lot of labels usage in boot code. This
commit has no effect on forth.bin.
2020-05-16 21:02:50 -04:00

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z80a also has words that behave similarly to IF..THEN and
BEGIN..UNTIL.
On the IF side, we have IFZ, IFNZ, IFC, IFNC, and THEN,. When
the opposite condition is met, a relative jump is made to
THEN,'s PC. For example, if you have IFZ, a jump is made when
Z is unset.
On the BEGIN,..AGAIN, side, it's a bit different. You start
with your BEGIN, instruction, and then later you issue a
JRxx, instr followed by AGAIN,. Exactly like you would do
with a label.
(cont.)