GMS90C320
OCT. 2000 Ver 1.2
9
CPU
The GMS90C320 is efficient both as a controller and as an arithmetic processor. It has extensive facilities for binary and BCD
arithmetic and excels in its bit-handling capabilities. Efficient use of program memory results from an instruction set con-
sisting of 44% one-byte, 41% two-byte, and 15% three-byte instructions. With a 12 MHz crystal, 58% of the instructions are
executed in 1.0
µ
s.
Special Function Register PSW
Reset value of PSW is 00
H .
Bit
Function
CY
Carry Flag
AC
Auxiliary Carry Flag (for BCD operation)
F0
General Purpose Flag
RS1
0
0
1
1
RS0
0
1
0
1
Register Bank select control bits
Bank 0 selected, data address 00
H
-07
H
Bank 1 selected, data address 08
H
-0F
H
Bank 2 selected, data address 10
H
-17
H
Bank 3 selected, data address 18
H
-1F
H
OV
Overflow Flag
F1
General Purpose Flag
P
Parity Flag
Set/cleared by hardware each instruction cycle to indicate an odd/
even number of “one” bits in the accumulator, i.e. even parity.
MSB
LSB
Bit No.
7
6
5
4
3
2
1
0
Addr. D0
H
CY
AC
F0
RS1
RS2
OV
F1
P
PSW