SN8F2250B Series
USB 2.0 Full-Speed 8-Bit Micro-Controller
2.1.4.4 ACCUMULATOR
The ACC is an 8-bit data register responsible for transferring or manipulating data between ALU and data memory. If
the result of operating is zero (Z) or there is carry (C or DC) occurrence, then these flags will be set to PFLAG register.
ACC is not in data memory (RAM), so ACC can’t be access by “B0MOV” instruction during the instant addressing
mode.
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Example: Read and write ACC value.
; Read ACC data and store in BUF data memory.
MOV
; Write a immediate data into ACC.
MOV
BUF, A
A, #0FH
; Write ACC data from BUF data memory.
MOV
A, BUF
A, BUF
; or
B0MOV
The system doesn’t store ACC and PFLAG value when interrupt executed. ACC and PFLAG data must be saved to
other data memories. “PUSH”, “POP” save and load ACC, PFLAG data into buffers.
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Example: Protect ACC and working registers.
INT_SERVICE:
PUSH
…
; Save ACC and PFLAG to buffers.
.
…
POP
; Load ACC and PFLAG from buffers.
RETI
; Exit interrupt service vector
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