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Scaled-index addressing mode
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oldben
Joined: Mon Oct 07, 2019 2:41 am
Posts: 698
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On may latest TTL cpu (8.16.32 bits) I have a free opcode slot, so I made that a prescaled addition
axw a + (efa) << 1 -- add index word
axh a + (efa) << 2 -- add index half (short)
OPCODES: SUB ADD AND OR XOR (ADD INDEX) LD ST
SIZE: BYTE(UNSIGNED)(8) SHORT(16) WORD(32)
ADRESSING MODES 0..6 INDEXED 7 immedate(PC)
if I limit myself to 1 meg adressing, all instructions are 1 world long
except immediate long, witch is two words.
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