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PostPosted: Tue Jan 01, 2013 9:45 am 

Joined: Sat Sep 15, 2012 9:49 am
Posts: 8
Location: Brisbane, Australia
Hi. I've read the 68000 Programmer's Reference Manual and the User Manual. I have written many assembler programs on the Amiga computer.

I'm trying to flesh out my knowledge of the 68000 with the intention of building a 68000-based computer. However, there are some things that I don't understand, perhaps because they are not well documented or perhaps because I'm just thick.

For example, the 68010 has alternate function code registers, SFC and DFC. The User Manual says at 2-3 that "The SFC and DFC registers allow the supervisor to access user data space or emulate CPU space cycles." But I still don't have any idea how to use them.

Is there some additional reference for the 68k that bridges the gap between hardware and software?

PostPosted: Tue Jan 01, 2013 10:29 am 

Joined: Mon Dec 27, 2004 11:40 pm
Posts: 318
The MOVES instruction uses either SFC, the source function code register, or DFC, the destination function code register, to set the code on the function code pins, FC0, FC1 and FC2, during the external accesses.

The function code pins indicate the type of external access being made.


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