HP-25C Eumulator

[Chris Chung]

@Neil Hamilton

I was thinking that may be hp41cx will be interested to be a tester, as he had indicated that he likes to have multiple units. If hp41cx is not interested, will you be interested to be a tester? the shipping will be less within Canada.

BTW, tester still need to pay. I am very over budget on this project. I am thinking $30 + shipping. Of course if anyone wants to roll-your-own, I am happy to release the PCB design upon PM requests.

Anyway if there is no taker, I will test it to my best capability. We (myself and potential kit grabbers) do need to decide if we need a new PCB, mainly because the current version does not have the right (or any) silk-screen prints. We could however leave it as is. Or adopt one of the three key layouts, i.e. HP-21, HP-25 or HP-33. Doing a new board will take 15-20 days.

(10-07-2014 06:47 PM)Neil Hamilton Wrote:  I am in Ottawa so may be close to you -- give or take up to about 4300 klicks :-) More if you are in Nunavut.

I am 450 clicks south west of you.

(10-07-2014 06:47 PM)Neil Hamilton Wrote:  I'm am electronic eng who broke out his real 25 partly because of this project. I spent some of the weekend pouring over your and Eric's code to see how things worked. If you are stuck I might be able to help. Used to have a 33E as well. Really interested in the 34C version as well.

Thanks in advance. The core emulator written by Eric is very robust. I only change the size of the register structures so they will fit in the micro. It's the glue code that ties the MCU IOs that needs to be tested properly. The LED multiplexing, keyboard scanning and other timing issues. The current firmware is very tight and of the 16K flash, I have only less than 50 bytes to spare. I have may be 60-70 bytes of stack which I hope it will not be over-run (so far my test shows that it's adequate).

I haven't retry the 34C after re-factoring the code. When it runs, it takes up all the flash memory and there is only 2/3 of the program steps. I will re-visit that after the securing the current firmware. The 34C has the biggest ROM.