I harbor a secret fantasy (oops, not so secret anymore) to build a simple computer from scratch. I'm looking for an easy-to-use microprocessor to start with. I know about the usual suspects such as the 6502, 68000, 8086, Z80, etc. But I'm wondering if something better is out there. Here's my wish list:
- Low clock rate (4-25 MHz)
- No more than 40-60 pins, preferably in DIP configuration
- Ability to address around 64KB of memory, but up to 1MB or so would be good
- Stored-program architecture (not read-only instruction space) (Edit: this rules out most low-end microcontrollers, like the PIC and AVR)
- Flat memory model, not banked or segmented like the 8086
Would like, but not necessary to have:
- RISCy instruction set (load-store)
- General-purpose registers
- Assortment of TTL I/O pins
- Built-in flash ROM
What microprocessor or microcontroller would you suggest that's relatively easy to wire up and get the first ROM routines written for?
My goal is to get a simple Forth (or similar) system going. Just to say I did it.
Edit: After doing a bit of research, I think something like the ARM7 would suit me. It comes with a non-trivial amount of flash and SRAM to play with -- sometimes as much as 256K flash and 64K SRAM -- along with digital I/O, ADC, serial I/O, and more.
Here's one: the STR711 ARM development board.