GMS84512 Datasheet, PDF (16/123 Pages) Hynix Semiconductor – 8-BIT SINGLE CHIP MICROCOMPUTER

GMS 84512 / 84524
2.1.1. A - Register
l 8 bit Accumulator
l In the case of 16-bit operation, compose the lower 8-bit of YA (16-bit Accumulator)
l In the case of multiplication instruction, execute as a multiplier register.
After multiplication operation, the lower 8-bit of the result enters. (Y * A → YA)
l In the case of division instruction, execute as the lower 8-bit of dividend.
After division operation, quotient enters. (YA ¡À X ¡æ Q: A , R: Y )
2.1.2. X- Register
l General-purpose 8-bit register
l In the case of index addressing mode within direct page(RAM area), execute as index
register
l In the case of G mode operation, execute as destination address register.
The operation result enters into memory indirectly addressed by X register.
l In the case of division instruction, execute as divisor register.
2.1.3. Y- Register
l General-purpose 8-bit register
l In the case of index addressing mode, execute as index register
l In the case of 16-bit operation instruction, execute as the upper 8-bit of YA (16-bit
accumulator).
l In the case of multiplication instruction, execute as a multiplicand register.
After multiplication operation, the upper 8-bit of the result enters.
l In the case of division instruction, execute as the upper 8-bit of dividend.
After division operation, quotient enters.
l Can be used as loop counter of conditional branch command. (e.g. DBNE Y, REL)
2.1.4. Stack Pointer
l In the cases of subroutine call, Interrupt and PUSH, POP, RETI, RET instruction,
stack data on RAM or in the case of returning, assign the storage location having
stacked data.
l Stack area is constrained within 1-page (00H-FFH). Page is fixed by H/W. User can
only assign the lower address. At the initial stage, stack pointer should be initialized to
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