NP-41 Emulator (may be)

[rprosperi]

(01-25-2016 07:03 PM)Chris Chung Wrote:  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.

So, it sounds like the basics are there. In a nutshell, Diego's product is a Flash chip with some logic, that emulates up to 12 of the 4K ROM Pages. He has built an easy-to-use Windows utility to "install" various ROM images, thus allowing one to utilize all the old (and even recently released) ROMs. So accommodating this single "chip" opens-up access to all the application ROMs, with each user building his/her own combination, and not requiring any of the internal ROM/RAM space.

But I agree the core feature is to allow easy import/export of FOCAL programs. There are several (Gene, Massimo, Warren, Angel, others - a little help with specifics?) available program file formats already existing, so when you look at that aspect, no need to reinvent something, the existing one(s) have not only figured all that out, there are libraries of programs already in that/those formats to test with and use, and possibly also reusable utility programs for USB transfers.

Very, very cool project!