NEC PD750008 User Manual
Page 50
3 0
µPD750008 USER'S MANUAL
(a) Specific address bit direct addressing (fmem.bit)
In this addressing mode, peripheral equipment that frequently performs bit manipulations involving,
for example, I/O ports and interrupt flags, can be processed at all times regardless of memory bank
setting. Accordingly, the data memory addresses that allow this addressing mode to be used are FF0H
to FFFH where I/O ports are mapped, and FB0H to FBFH where interrupt-related hardware is mapped.
Hardware mapped to these data memory areas can freely perform bit manipulations in the direct
addressing mode at any time regardless of MBS and MBE setting.
Examples 1. Value input to P02 is inverted, and the result is output on P33.
MOV1
CY, PORT0.2
NOT1
CY
MOV1
PORT3.3, CY
2. The timer 0 interrupt request flag (IRQT0) is tested. The request flag, if set, is cleared,
and P63 is reset.
SKTCLR
IRQT0
; IRQT0 = 1?
BR
NO
; NO
CLR1
PORT6.3
; YES
3. If both P30 and P41 are set to 1, P53 is reset.
MOV1
CY, PORT3.0
; CY <– P30
AND1
CY, PORT4.1
; CY P41
NOT1
CY
; CY <– CY
MOV1
PORT5.3, CY
; P53 <– CY
P53
P30
P41