NP-41 Emulator (may be)

[rprosperi]

(01-25-2016 09:34 PM)Chris Chung Wrote:  I would love to explore more on ROM module. And I am a newbie on the HP-41C. I acquire my knowledge on Eric's Nonpareil under Linux, and as you mentioned there is no support of ROM modules. So I never see how it works! I would imagine that once a module is "parked" into one of the 4 ports (is it 4?), additional functions / programs will show on the "CAT" list and be available for use.

I can see there are microcode instructions to check memory location availability and I assume the boot code will do that to determine / setup when ROM modules are present. Currently on NP41 these functions are blocked. And I would like to explore them.

Would you suggest a very basic ROM module where I can download the binary and play w/? This is the only way I could understand the mechanism better. I used to run gdb w/ nonpareil to understand certain mechanism.

Yes, the 41C family had 4 physical Ports, each of which could address 2 x 4K "Pages", and said Pages could also be banked up to 4 layers deep. Note that 41C ROM code consists of 10-bit "words" (I may not have the exact terminology correct). Port-1 addressed Pages 8/9, Port-2 - A/B, Port-3 - C/D, and Port-4 - E/F. As you guessed, the Functions in these ROMs were added into the CAT-2 listing.

There are,also some special cases, where devices inserted into physical ports were mapped to different memory Pages, e.g. the Printer was mapped to Page-6, HP-IL Mass Storage to Page-7, and others.

I will email you a copy of Paul Kaarup's Superb "HP-41 Programmers Handbook". It contains a huge amount of useful information all in one place, and may provide insights and reference material as you explore this.

I can also email you a sample ROM image (e.g. for the MATH ROM) if that's what you mean.