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41CL MMU Backup
05-30-2020, 03:52 PM (This post was last modified: 05-30-2020 04:07 PM by Ángel Martin.)
Post: #12
RE: 41CL MMU Backup
(05-30-2020 08:27 AM)grsbanks Wrote:  Would another solution not be to copy YFNX into a RAM page and point the MMU to it there rather than in flash?

That way, YMCPY doesn't need to be copied to page 4 in the first place because it's already running from RAM rather than ROM.

The transient code snippet is copied by YFWR to a RAM page, not to flash.
Then the MMU is changed to map Page#4 to that RAM page, and the MCODE execution is sent to page#4
The MCODE runs there, including a final remapping of page#4 to the original flash/RAM block.

And herein lies the issue: if you're copying 804 to 1FE that requires YFWR , which modifies the 804 content on the fly during the copying. Sure it undoes that modification but not before the modified one was copied to 1FE.

The question is which other RAM page could be used to copy the transient code and map it to Page# - specifically how to guarantee it's always available for this purpose.

801, 802 and 803 come to mind but they're also used by the CL Xpanded backups, the the Y-Registers functions and the Y-Matrix extensions of the SandMatrix...

805 is already reserved for the IMDB location in RAM

and above those you get into the standard RAM, which is user-dependent.
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Messages In This Thread
41CL MMU Backup - twoweims - 05-28-2020, 10:15 PM
RE: 41CL MMU Backup - Monte Dalrymple - 05-29-2020, 04:07 PM
RE: 41CL MMU Backup - twoweims - 05-29-2020, 04:44 PM
RE: 41CL MMU Backup - Monte Dalrymple - 05-29-2020, 05:49 PM
RE: 41CL MMU Backup - twoweims - 05-29-2020, 08:50 PM
RE: 41CL MMU Backup - Monte Dalrymple - 05-29-2020, 10:09 PM
RE: 41CL MMU Backup - twoweims - 05-30-2020, 01:05 AM
RE: 41CL MMU Backup - Ángel Martin - 05-30-2020, 05:22 AM
RE: 41CL MMU Backup - twoweims - 05-30-2020, 02:32 PM
RE: 41CL MMU Backup - Ángel Martin - 05-30-2020, 03:45 PM
RE: 41CL MMU Backup - Ángel Martin - 05-31-2020, 06:09 AM
RE: 41CL MMU Backup - grsbanks - 05-30-2020, 08:27 AM
RE: 41CL MMU Backup - Ángel Martin - 05-30-2020 03:52 PM
RE: 41CL MMU Backup - Monte Dalrymple - 05-30-2020, 06:47 PM
RE: 41CL MMU Backup - rprosperi - 05-30-2020, 10:36 PM
RE: 41CL MMU Backup - Monte Dalrymple - 05-30-2020, 11:58 PM
RE: 41CL MMU Backup - rprosperi - 05-31-2020, 03:00 AM
RE: 41CL MMU Backup - Monte Dalrymple - 08-07-2021, 02:07 AM
RE: 41CL MMU Backup - Ángel Martin - 05-31-2020, 06:55 AM
RE: 41CL MMU Backup - Monte Dalrymple - 05-31-2020, 06:22 PM
RE: 41CL MMU Backup - twoweims - 05-30-2020, 08:26 PM
RE: 41CL MMU Backup - Monte Dalrymple - 05-30-2020, 10:07 PM
RE: 41CL MMU Backup - twoweims - 05-31-2020, 06:30 PM
RE: 41CL MMU Backup - rprosperi - 05-31-2020, 06:51 PM
RE: 41CL MMU Backup - twoweims - 05-31-2020, 07:44 PM
RE: 41CL MMU Backup - rprosperi - 05-31-2020, 08:09 PM
RE: 41CL MMU Backup - twoweims - 06-01-2020, 09:24 PM
RE: 41CL MMU Backup - Monte Dalrymple - 06-01-2020, 10:48 PM
RE: 41CL MMU Backup - twoweims - 06-01-2020, 11:48 PM
RE: 41CL MMU Backup - Monte Dalrymple - 06-02-2020, 01:42 AM
RE: 41CL MMU Backup - grsbanks - 06-04-2020, 07:14 PM
RE: 41CL MMU Backup - Monte Dalrymple - 06-04-2020, 08:50 PM



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