For a long time, I was a bit of a Z80 snob, I have to admit. “That 6502 only has 3 registers and a single accumulator! How can you get anything done with so little working space?” I would say to 6502 fans. Well, I started to understand last year when I began writing an assembly language program for my Commodore 64. The constraints and flexibility of the 6502 are what appeal to fans, and now when I see boards like the rosco_6502 r4 kit I get very tempted to pick one up!
The rosco (which stands for Really Old-School Company) board is a pretty beefy 6502 single-board computer, with 528 kB of RAM, 8 kB of ROM (expandable to 32 kB) and a powerful XR68C681 dual UART for lots of I/O. It’s a fully through-hole design, so it’s fairly easy to put together, and it comes with a great serial monitor that allows full control of the processor. SD card support is included, as well as a bootloader that allows you to load .hex files over the serial port for easy testing!
You can also pull the EEPROM and program it directly if you choose, giving you complete control of the entire board, from the boot process onward. A simple FTDI dongle provides power and serial data when debugging, but there’s also a barrel jack to power the board if you need more current. It’s using a true WDC 65C02, the more modern CMOS variant of the chip. This makes interfacing it with modern boards and systems a snap. There’s also a full breakout header giving access to the CPU bus, so you can add your own peripheral cards and create something truly unique.
If you’ve ever wanted to give the 6502 a serious try, the rosco_6502 board looks like a great place to get started!
