Hello from New Hampshire!

ECWhitney · Post by **ECWhitney** » Mon Sep 13, 2021 11:13 am

My interests in the X16 are based in nostalgia for the 6502 processor that I first learned to program in machine language on a SYM-1 board that I’m in the process of restoring, thanks to the inspiration I got from watching Dave’s channel.

By day, I’m an electrical engineer with 30 years of FPGA and ASIC design experience so if you’re looking for any help along those lines, give me a shout.

I really like the X16’s Phase 1 concept as a kit—I can see the benefit of using this as a valuable education tool. I’ve thought about writing the 6502 processor in Verilog as an FPGA exercise, I just never seemed to find the time to do it…

Erich Whitney

Derry, NH

picosecond · Post by **picosecond** » Mon Sep 13, 2021 12:24 pm

Hey neighbor, welcome.

1 hour ago, ECWhitney said:

I’ve thought about writing the 6502 processor in Verilog as an FPGA exercise, I just never seemed to find the time to do it…

Ditto. It's never going to happen while I am still working, but it seems like a fun post-retirement project. That's not too many years out at this point.

ECWhitney · Post by **ECWhitney** » Mon Sep 13, 2021 12:58 pm

Agreed!

Meanwhile, I'm restoring my SYM-1 board and giving it a slight tech-refresh. The original plastic sockets are very flaky so I'm replacing them with proper machined DIP sockets. And while I'm at it, I'm replacing the capacitors with modern equivalents. I've designed a memory expansion board that replaces the on-board RAM and ROM chips with a single 64K SRAM and a single 64K EEPROM. I'm using a custom GAL22V10 to manage the memory map. I also threw on a Supercap to hold the contents of the SRAM. I've found the SYM-1 BASIC interpreter and editor/assembler (which I never had when I was a kid). Those go in the EEPROM along with the SYM-1 Supermon 1.1. I'm going to tether the SYM-1 to a Pi/400 computer which will act as a terminal and host.

I think all the chips are good and I know I can get replacement 6502 and 6522--the one chip I'm worried about is the 6532 but there may well be some of these still on eBay if it turns out I need one...

I'm thinking it would be fun to use the X16 idea to make a SYM-16...too much fun...

-Erich