NoV-64D and HEPAX Questions

[Sylvain Cote]

(04-04-2024 05:23 AM)BitWiz Wrote:  1. According to the manual for the NoV-64D control register the NoV-64D can only map the HEPAX RAM at pages 8 - B in 16 K mode how can the HEPAX ROM go on Page 8? What am I missing here?

Yeah, this is a special case, the original HEPAX module was the first of this kind, effectively the HEPAX 10-bit ROM memory and the HEPAX 10-bit RAM memory share the same address space for a very short time, but since both memory are in the same module and are handled by the same logic, there is no memory lock-up.

(04-04-2024 05:23 AM)BitWiz Wrote:  2. I read through chapter 7 of the HEPAX manual and i didn't see where how to address QROM blocks in HEPAX RAM into the HP-41 ROM space?

The HP-41 has two type of memory, the 10-bit word kind and the 56-bit register kind.
The 10-bit word kind is organized into 16 pages (0 to 15) of 4K words for a total addressing space of 64K words.
Originally, only ROM was able to exist in this kind, but users decided to create RAM and/or EPROM boxes for mcode development purposes.
A 4k 10-bit RAM page is called a QROM page (Quasi-ROM) and HEPAX RAM pages are QROM.
We calling this differently because it indicate who is in charge of that page, if the HEPAX ROM logic is in charge, then it is a HEPAX RAM page, if not, it is a QROM page.

(04-04-2024 05:23 AM)BitWiz Wrote:  Or even how to load multiple bank ROMs into the HEPAX RAM as QROMS.

Full stop!
NoV modules support 4k banks switching for its 10-bit Flash memory (aka ROM)
but does not support 4k banks switching for its 10-bit FRAM memory (aka QROM & HEPAX RAM).

(04-04-2024 05:23 AM)BitWiz Wrote:  Bob Prosperi said that I would need to load each bank into bank 0 of the HEPAX ROM space and then copy it to the appropriate location in the HEPAX RAM and configure that 4K for the appropriate HP-41 Page and Bank.

I am not following that logic and why you would need to copy things from NoV Flash pages to NoV FRAM pages.