740 REGISTER SET
The following is a list of the 740 registers used by AS740:
a - 8-bit accumulator
x,y - index registers
740 INSTRUCTION ADDRESSING MODES
The following list specifies the format for each
addressing mode supported by AS740:
#data immediate data byte
#data,*zp immediate data to zero page
a accumulator addressing
*zp zero page addressing
(see .setdp directive)
0 <= dir <= 255
*zp,x zero page x addressing
*zp,y zero page y addressing
address = (offset + (x or y))
[*zp,x] indirect x addressing
0 <= offset <= 255
address = 2 bytes at location
[(offset + (x or y)) mod 256]
[*zp],y indirect y addressing
address = 2 byte value at offset
plus the value of the y register
abs absolute addressing (2 byte)
abs,x absolute x addressing (2 byte + x)
abs,y absolute y addressing (2 byte + y)
[abs] indirect addressing (2 byte)
label branch label
\special low order byte of address 0xFFnn
BIT#,*zp bit set/clear zero page
BIT#,A bit set/clear accumulator
BIT#,*zp,label branch on bit set/clear in zero page
BIT#,A,label branch on bit set/clear in accumulator
The terms data, zp, abs, BIT , special, and label may all be ex-
pressions.
Note that not all addressing modes are valid with every in-
struction, refer to the 740 technical data for valid modes.