Chapter 2 Hardware Summary

By: Masud-ul-Hasan

•OV: (Overflow flag) is set after an addition or subtraction operation if there was an arithmetic overflow. Results greater than +127 or less than –128 will set OV bit. •P: (Parity Bit) automatically set or cleared each machine cycle to establish even parity with the accumulator. Parity bit is most commonly used in conjunction with serial port routines to include a parity bit before or after the transmission.

•RS1 & RS0 are used to select different register banks.

PSW(Contd.)

RS1 RSO Register Bank Address

0 0 0 00h - 07h

0 1 1 08h - 0Fh

1 0 2 10h - 17h

1 1 3 18h - 1Fh