C515 Datasheet, PDF (14/55 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

C515
CPU
The C515 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 consisting of 44 % one-byte, 41 % two-byte, and 15% three-
byte instructions. With a 6 MHz crystal, 58% of the instructions are executed in 1.0µs (10 MHz: 600).
Special Function Register PSW (Address D0H)
Reset Value : 00H
Bit No. MSB
D7H
D0H CY
D6H
AC
D5H
F0
D4H
RS1
D3H
RS0
D2H
OV
D1H
F1
LSB
D0H
P
PSW
Bit
Function
CY
Carry Flag
Used by arithmetic instruction.
AC
Auxiliary Carry Flag
Used by instructions which execute BCD operations.
F0
General Purpose Flag
RS1
Register Bank select control bits
RS0
These bits are used to select one of the four register banks.
RS1
RS0
Function
0
0
Bank 0 selected, data address 00H-07H
0
1
Bank 1 selected, data address 08H-0FH
1
0
Bank 2 selected, data address 10H-17H
1
1
Bank 3 selected, data address 18H-1FH
OV
Overflow Flag
Used by arithmetic instruction.
F1
General Purpose Flag
P
Parity Flag
Set/cleared by hardware after each instruction to indicate an odd/even
number of "one" bits in the accumulator, i.e. even parity.
Semiconductor Group
14
1997-08-01