It’s hard to believe that MOS Technology released their 6502 8-bit microcontroller back in 1975. Even more surprising, is that 44 years later they are still being manufactured in one form or another (65XX) by Western Design Center, including PLCC and QFP variants — although it’s mostly garage engineers and hobbyists that continue to use them. One of those hobbyists, NotArtyom, took advantage of WDC’s PLCC and QFP 6502 form factors and was able to build a watch around them.
“I went off to try and design the smallest 6502 SBC I could, and was pleasantly surprised with the results. What I ended up with was what I think is the smallest hobbyist 6502 SBC produced. Small enough, in fact, that you could easily wear it on your wrist!”
NotArtyom’s watch design is pretty straightforward, and uses a PPLC 6502 (32K of SRAM/16K of ROM) for the main microcontroller, along with a PPLC 6522 to handle I/O options. The chips are housed on a custom PCB with a Nokia 5110 LCD and four programmable buttons to navigate through the watch’s functions.
On the software end, NotArtyom states the watch employs a few essential programs, including G’Mon, a generic monitor that can modify memory, which he used as the primary development utility. He also used EhBasic to tap into the watch’s Kernal and its init and hardware interface routines. Finally, the last piece of software that was implemented on the ROM is the Watch Menu, which allows you to select what program the user wants to run.
NotArtyom did a great job on his 6502 Watch, and he’s listed the schematics and other data on his website for those who would like to recreate his project.