🚀 go-pugleaf

In article <MDC-SMB-9K5PJ@OFFICE-1>, SMB.MDC@OFFICE-1.ARPA writes:
> Is there a way to replace the MFP interrupt service routines with a user 
> written version? I've been looking for a table which contains the address of 
> the ISRs, but haven't been able to locate it.

68901 interrupts are based at 0x100:

	 Vector	   Function
	 0x100	   (disabled) Centronics BUSY
	 0x104	   (disabled) RS232 Carrier Detect
	 0x108	   (disabled) RS232 Clear-To-Send
	 0x10c	   (disabled) 68901 timer D (RS232 baud rate)
	 0x110	   (disabled) GPU operation done
	 0x114	   200hz System clock (timer C)
	 0x118	   Keyboard/MIDI (wire-ORed interrupts from both 6850s)
	 0x11c	   (disabled) Floppy/hard disk controller
	 0x120	   (disabled) Horizontal blanking counter (timer B)
	 0x124	   RS232 transmit error
	 0x128	   RS232 transmit buffer emtpy
	 0x12c	   RS232 receive error
	 0x130	   RS232 receive buffer full
	 0x134	   (disabled) 68901 timer A
	 0x138	   (disabled) RS232 ring indicator
	 0x13c	   (disabled) Polled monitor type

> Is the BIOS in a different location in the 1040ST? I have the ST
> internals book and the BIOS listing doesn't seem to be correct for my
> computer.

The ROMs for the 520ST and the 1040ST are identical.  The BIOS listing
you have is from the first RAM-loaded release of the system, not from
the later ROMs.  The listing is useful in that it gives examples (e.g.
how to twiddle the ST's hardware), but DON'T expect the addresses or
code in the ROM to match your listing.


-Landon
-- 

-Landon Dyer, Atari Corp.		{lll-lcc,lll-crg!vecpyr}!atari!dyer

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