How does AND operation in Z80 cpu overflow?

Question

I am referencing zilog z80 manual and i am little puzzled reading at AND instruction. It says in the 'condition bits affected' section, P/V flag is set if the operation overflows. I can understand how add or sub instruction overflows but it doesn't make sense for me that AND operation overflows. Any help is appreciated!! Thanks!

score 4 · Accepted Answer · answered Nov 25 '12 at 07:01

4

According to this page, the P/V bit serves two purposes. The result for the AND instruction is really the P function, that is, the P bit is set if there are an even number of 1 bits in the result of doing the AND.

answered Nov 25 '12 at 07:01

Greg Hewgill

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I am sorry if i missed it but is it written somewhere that parity P flag is affected during AND operation? Thanks!! – kofhearts Nov 26 '12 at 02:48
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Yes, on the linked page, the line that reads `AND r SZ513P00` – Greg Hewgill Nov 26 '12 at 02:51

How does AND operation in Z80 cpu overflow?

1 Answers1