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HP41CL serial export of ROM
02-13-2017, 07:35 PM
Post: #2
RE: HP41CL serial export of ROM
(02-13-2017 07:07 PM)dingebre Wrote:  I "YPEEK"ed into the MMU register that contains the pointer to the Page B HEPAX data. On my calculator, I YPEEKed into 0x8040B0 which should be Page B, Bank 1, and got 8808 in return as the "data". I take that to mean location 0x808808, right? When I YPEEK that location, I get 0000 for data. If I YPEEK 0x880800, I get 0514 for data. When I use HEXEDIT at page F000 and F001 I get 01F and 040 as the entries at that memory location.

How do I find where in the 41CL RAM memory space the HEPAX RAM is located?

Second, when I physically plug a module into the 41CL, how do I find out where that ROM is mapped so that I can export it? This would also apply to a NOV-64 module that has HEPAX RAM in it, too.

Despite having read the manual, if it's in there, please point me. Just because I read it, doesn't mean I actually understood it. In all fairness, I think it's clear I missed something.


The MMU register arrangement is shown in the figure on page 67 of the manual. The most-significant nibble contains control information (enabled/locked/type), while the lower three nibbles contain the physical page address to substituted for the logical page address. In the example you asked about, RAM page 808 (starting address 0x808000) is what is plugged into page B. The upper nibble indicates that MMU translation is enabled, the page is not locked, and it is a single page image.

For your second question, the figure on page 30 shows how to specify a logical address to copy into RAM. The image needs to be in RAM before it can be exported.

Hope this helps.
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Messages In This Thread
HP41CL serial export of ROM - dingebre - 02-13-2017, 07:07 PM
RE: HP41CL serial export of ROM - Monte Dalrymple - 02-13-2017 07:35 PM
RE: HP41CL serial export of ROM - dingebre - 02-14-2017, 05:39 PM

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