NP-41 Emulator (may be)

[Chris Chung]

(01-25-2016 04:23 PM)rprosperi Wrote:  Chris - This project is moving along nicely, it's exciting to watch it evolve. One suggestion to consider - perhaps there is a way (socket?) to accommodate some sort of chip from Diego, to allow "insertion/upgrade/whatever" enabling use of ROMs (RAM, etc.) using his NoV-64d design. This single socket would basically open up the design to allow use of ALL the 41 ROMs, including esoteric stuff like CCD, HEPAX, Zenrom, etc.

I've no idea if Eric's code even accommodates expansion ROMs, etc. so this may not even be feasible, but it would dramatically expand what one could do with this DIY 41C, allowing folks to buy an upgrade chip from Diego if they desire to expand their system.

Just an idea...

I am rather new to HP-41 and had not explore the ROM and peripheral options. In Eric's code, there are provisions made to bank switch the 16 page of 4k ROM / RAM addresses. I will have to do more reading to understand both the code and the HP-41 architecture before fixing a solution.

I did play around w/ different program listings. Initially via manual key in. And after a while got lazy and developed a way to "save" and "load" them via the MCU programming interface. My personal goal / plan is to hack together some utilities so that I can cut and paste program listing from this site, compile and download them to NP41 via USB-Serial cable to play w/. As I am not a old-time user, the extension / peripheral system is still new to me and it is unwise to dictate a interface. It is, though, possible to add a SD card reader to the system to make available ROM images.

Another thing to consider is that I am using this "value line" MSP430 MCU. It has 56K flash and 4K ram. The CV's 319 registers are within this 4K space and the simulator + boot rom is using around 36K. So there is not much room for storage or emulate from RAM.

I did allocate 8+ GPIO pins (including hardware SPI / I2C) for expansion. So serial ROM / RAM is possible, except may be slower execution as there will be fetch time penalties.

However I will be very interested to know what potential users want and see if additional requirements can be implemented.

The current goal is to deliver a basic HP-41CV functionality at a low cost reliably w/ Eric's base code. Though I would definitely put in some program "save and load" functionality.