(SOLVED) 41CL - DOUBLE HEPAX ACCESS and MMU CONFIG

[Sylvain Cote]

(08-24-2019 05:13 AM)Ángel Martin Wrote:  

(08-23-2019 11:09 PM)rprosperi Wrote:  OK, thanks. I was aware of that in the NEWT (which has power and speed to spare), but did not think the HEPAX module had such sophisticated capabilities back in 1987. The more I learn about it, the more impressive it is.

There are other examples: The Advantage Pac and the IR printer module also act on "special" OpCopes to switch their banks .... so it was not only the HEPAX. Also the ZEPROMS implemented their own bank-switching scheme... so imagine: the NUT CPU is happily NOPing while all that wild bank switching happens ;-)

In the end, we were somewhat lucky that HP did not upgrade their NUT CPU and used theses opcodes to do something else.

(08-24-2019 05:13 AM)Ángel Martin Wrote:  As to the WRTROM/READROM instructions, absolutely they can be used on HEPAX RAM pages - so the user could (re)store their HEPAX RAM contents on disk.

I still need to test these ones, right now I am successfully writing and reading HRAM test pages using WRTPG/READPG from PowerCL 4X ROM.

(08-24-2019 05:13 AM)Ángel Martin Wrote:  In fact, moving to the CL now, the user can have MULTIPLE sets of HEPAX RAM blocks in sRAM and manage them via (UN)PLUG commands to swap the sets on demand.

Yep! as demonstrated in the post #19 on this thread.

(08-24-2019 05:13 AM)Ángel Martin Wrote:  Even more interesting, with the HEPAX_4H revision two sets of HEPAX RAM pages can be plugged-in simultaneously and the Hepax FileSystem addressing can change the mapping of the respective sets. This requires functions HEPINI and HEPCHN but it really is quite easy.

I do use the 4H ROM revision (HEP2) unfortunately the last version of the document that I found is 1G.
I will have to re-read the HePaX chapter of your PowerCL version 4N manual because I never grasp that is was possible.
The possibility of having multiple HRAM set was always there, in fact when you copy 4 CL templates (0x0B9) to build a 16K set, you have 4 unlinked 4K HRAM memory until you linked them.
As far as I know, the problem is that the HePaX ROM will only look for the first HRAM.

(08-24-2019 05:13 AM)Ángel Martin Wrote:  Impressive indeed...

Wholeheartedly agree!

edit: typo