The 6502 CPU's overflow flag explained at the silicon level
Linked by Thom Holwerda on Tue 15th Jan 2013 22:29 UTC
Hardware, Embedded Systems "In this article, I show at the transistor and silicon level. I've discussed the mathematics of the 6502 overflow flag earlier and thought it would be interesting to look at the actual chip-level implementation. Even though the overflow flag is a slightly obscure feature, its circuit is simple enough that it can be explained at the silicon level."
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RE: Comment by Kroc
by Valhalla on Wed 16th Jan 2013 16:30 UTC in reply to "Comment by Kroc"
Valhalla
Member since:
2006-01-24

I did some brief programming on the 65816 back in the day (it was used in the Super Nintendo amongst others).

I remember going like 'yay, a 6502 with 16-bit registers!', unfortunately as I recall there were no separate opcodes for using 8 or 16 bit registers so instead you had to switch between 8/16-bit by setting a 'mode' bit in the status register with rep,sep instructions which quickly became tedious.

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