Re: BRK opcode

From: Brian Ketterling (
Date: 2003-11-08 01:59:33

>From: "Daniele Gratteri" <>
> > The same thing also happened at Intel: some 8088 engineers left to start
> > Zilog so they could pursue their own better idea, the Z-80.
>I think the Intel CPU you are actually referring to is the 8080: in fact,
>the Z80 is instruction compatible with that CPU.

I think you're right.

As far as "BRK" on the 6800, I found the SWI (software interrupt) 
instruction via Google, and also kind of a spif website:

with instruction-set "reference cards" for many microprocessors.  The 6800's 
instructions look like a superset of the 6502's.

Steve Judd said he recalled having Sirius (my assembler of choice nowadays, 
btw -- thanks, Steve!) assemble BRK as two bytes, and I see in the 65C816 
data sheet that the second byte is regarded as a "signature byte" -- but 
isn't used for anything?!

-- Brian

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