NEC PD750008 - Manual (Page 258)

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µPD750008 USER'S MANUAL
11.1.2 Bit Manipulation Instructions
With the µPD750008, a variety of instructions are available for bit manipulation.
(a) Bit setting: SET1 mem.bit
SET1 mem.bit*
(b) Bit clearing: CLR1 mem.bit
CLR1 mem.bit*
(c) Bit testing: SKT mem.bit
SKT mem.bit*
(d) Bit testing: SKF mem.bit
SKF mem.bit*
(e) Bit testing and clearing: SKTCLR mem.bit*
(f) Boolean operation: AND1 CY,mem.bit*
OR1 CY,mem.bit*
XOR1 CY,mem.bit*
mem.bit* represents a bit address addressed by using a bit manipulation addressing mode (fmem.bit,
pmem.@L, or @H+mem.bit).
Particularly, all of these bit manipulation instructions can be used for the I/O ports, so that I/O port
manipulation can be performed in a very efficient manner.
11.1.3 String-Effect Instructions
With the µPD750008, two types of string-effect instructions are available.
(a) MOV A,#n4 or MOV XA,#n8
(b) MOV HL,#n8
"String effect" means the locating of these two types of instructions at contiguous addresses.
Example A0: MOV A,#0
A1: MOV A,#1
XA7: MOV XA,#07
When string-effect instructions are arranged as in this example, if execution starts at address A0, the
following two instructions are replaced with an NOP instruction. If execution starts at address A1, the following
one instruction is replaced with an NOP instruction. That is, only the instruction first executed is valid, and
any following instructions are processed as an NOP instruction.
By using string-effect instructions, a constant can be set in an accumulator (the A register or the XA register
pair) or data pointer (the HL register pair) more efficiently.