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ACCCON TST

Posted: Thu Oct 31, 2019 12:42 pm
by Pernod
The Master service manual isn't very clear on which IO is paged out when the ACCCON TST bit is set. A diagram suggests only page &FE is IO/ROM, and there's no other mention of the TST bit.

I see b-em pages out pages &FC,&FD, &FE, which looks more likely as the MOS contains credits in these pages. Does any software/hardware make use of this bit to act as a test case? The only use I can think of is to checksum the MOS.

So which is it, just page &FE or pages &FC,&FD,&FE?

Re: ACCCON TST

Posted: Thu Oct 31, 2019 1:03 pm
by tom_seddon
MOS 3.50 has code in these pages.

Good point about pages $fc and $fd - I'd always assumed it was all 3 pages that were paged out, but come to think of it I'm not sure I ever actually tested this...

--Tom

Re: ACCCON TST

Posted: Thu Oct 31, 2019 1:17 pm
by Pernod
tom_seddon wrote:
Thu Oct 31, 2019 1:03 pm
MOS 3.50 has code in these pages.
I never noticed that before, but would suggest all 3 pages are paged out. Any idea what the code there does?

Re: ACCCON TST

Posted: Thu Oct 31, 2019 6:18 pm
by jgharston
My *MDUMP command will page out the I/O area, and confirms that all three pages are paged out.
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Re: ACCCON TST

Posted: Thu Oct 31, 2019 6:21 pm
by jgharston
Pernod wrote:
Thu Oct 31, 2019 1:17 pm
tom_seddon wrote:
Thu Oct 31, 2019 1:03 pm
MOS 3.50 has code in these pages.
I never noticed that before, but would suggest all 3 pages are paged out. Any idea what the code there does?
It's part of the RESET startup code, clears memory, initialises hardware, sets up default vectors, copies default font, etc. Stuff that's only done once.

Re: ACCCON TST

Posted: Fri Nov 01, 2019 11:32 am
by Pernod
jgharston wrote:
Thu Oct 31, 2019 6:18 pm
My *MDUMP command will page out the I/O area, and confirms that all three pages are paged out.
Thanks for the confirmation, and code details.