HP48 hardware hacking -- SOIC EPROMS?

[Jonathan Busby]

(05-01-2019 07:32 AM)blackjetrock Wrote:  You might be able to find some of these obsolete ones, maybe:
https://www.digikey.co.uk/products/en/in...ageSize=25

Or, there are SPI flash chips that are in a 16 pin package. If you could find a suitable small FPGA you could create a parallel interface for the SPI flash chip.
Or, if you could find a suitable microcontroller in a SOIC32 and it was fast enough, you could maybe emulate a ROM?

Andrew

Thanks for the tip I hadn't considered using a small FPGA as I have several Xilinx FPGA dev boards and the FPGA chips aren't small enough, although, I bought those dev kits for CPU design which uses up a lot of resources ( A Digilent Arty using a Xilinx Artix-7 being my latest acquisition ). I guess if I could find a much smaller packaged FPGA I could use its distributed RAM as a "ROM". I'd have to include an SPI flash chip too though as the FPGA configuration data is volatile, which makes it kind of redundant. A better solution would be to use a very small 512KiB x 8 NAND flash chip. In terms of an MCU, I think I may be able to find one which is an SoC with a built-in FPGA and/or flash blocks. This would all still require the use of a daughterboard and the ICs would have to be quite small.

Regards,

Jonathan