NEC PD750008 Manuale Utente

µPD750008 USER'S MANUAL

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.

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.