There is an error in the information on this website concerning interrupts. Please see: http://homepage.ntlworld.com/cyborgsyst ... 02.htm#INT

Look at the last line under the "How can I DISable Interrupts?" section:

# This is done with the STI instruction.

Looks like someone was thinking 80x86 when they wrote that.

That page has a number of errors that have persisted for a number of years. Better to read Garth's interrupt primer, which is accurate.

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x86?  We ain't got no x86.  We don't NEED no stinking x86!

The SO pin:


The falling edge of SO pin will set the oVerflow bit.

I was reading the instruction reference of ASL while I noticed that the example is incorrect.

The pseudocode of the logic is saying that the highest bit is shifted into the Carry flag (P.C = B.7), but the below example is setting Carry to zero, while the highest bit before the shift operation was one.

Quite right. I wonder if they were experimenting using a buggy emulator.
Here's the proof:
http://visual6502.org/JSSim/expert.html ... a9ee0aeaea