Miscellaneous Instructions
z80
» Intermediate
There are four small instructions that are very handy
but I can't really categorize.
ccf
Compliment Carry Flag - Inverts the carry flag.
| cpl
ComPLiment accumulator - Inverts all bits in a . If
a was %11001111 then it would now be
%00110000 .
| neg
| NEGate accumulator - If a was
2 then it's now -2. See the Two's
Compliment Section.
| scf
| Set Carry Flag - No real reason but
just thought I'd tell you. Maybe use it for return
conditions on routines, like if there was an error during the
routine, it would set the accumulator, then the user could see if
there was an error by checking the carry flag.
| ldir
| LoaD (de ) with (hl ), Decrement
bc , Increment de and hl ,
and Repeat until bc is zero. It's
basically a block copy. It copies bc size to copy (amount of
bytes from hl to de ). ld hl,source_code
ld de,destination_code
ld bc,source_code_end-source_code
ldir
| | |
More from
z80
» Intermediate
All the Flags
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Debugging
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Down-Left Bug
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_GetKey Codes
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Logical Operators
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Memory, ROM, RAM, and Safe Areas
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Miscellaneous Instructions
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PC and SP
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Random Numbers
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TI's ROM Calls
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Restart Commands
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Simulated 16-bit Addition
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The Stack
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Tables and Arrays
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Text Display
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Variables