Behaviour of "SUB" instruction of TC264D

[André]

Hi all,

Can some explain me the behaviour of the TC264 when:

sub d1, d2 with d2 > d1

For e.g

d1 = 0xA

d2 = 0xFFFFFF00

The result is 0x10A, but why?

BR,

André

[MoD · Accepted solution]

d1 = 0xA = 10
d2 = 0xFFFFFF00 = -256

0x10A = 266 = 10 - (-256) = 10 + 256