My company (DDS) once offer a fairly powerful single-board embedded controller called BD52 (Bob&Daves 8052) - This had pretty good in-circuit emulation and in-circuit simulation capabilities with decent external interfaces.

Sadly I've used or given away the last of my stock, so I've decided to hand-build some new 8031/8032 boards, and just wanted to mention this and see if anyone else is interested in building and using some classic embedded hardware:

8031/8032 CPU, 32k EPROM, 32k RAM

ROM and RAM are mapped into single 64k address space (meaning you can download code and run if from RAM, and that code can access functions and data from ROM)

My ROM has about 13k of code in it, leaving about 18k for any stuff you might want to add "permanent". My ROM contains:

- In-Circuit emulation/simulation kernel compatible with my EMILY52 simulator MONICA52 in-circuit debugger (both free now)

- MinMon31 - a tiny "monitor", thats lets you download/upload, dump/edit memory, examing/write 8031 SFRs. Also needs only ROM, and serial port to function, so really helpful in bringing up the system for the first time.

- Full edition of my MON51 debug monitor, all of the above, plus breakpoints, single-step, disassembly and lots more.

- CFLEA virtual machine... This lets you use C code on a virtual CPU designed to be a very efficient target for my Micro-C compiler (also free now)

- I also adjusted, built and threw in an edition of the TinyBasic 8051 from: www.pjrc.com/tech/8051/contrib/tb51/index.html

The startup code normally launches MiniMon31 (where it is easy to launch any of the others), but does have an ability to use a 5-byte signature in the very top of RAM (FFFB-FFFF) to auto-launch any of them, or user code that has been downloaded. (I like to use NVRAM like the Dallas chips to make downloaded applications semi permanent and easy/fast to change)

This will be a very good little general controller, as well as a good way to experience and learn about a classic microcontroller system!

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The 8031 is a ROMless version of the 8051 which is a single-chip microcontroller. So... one of these systems is dead easy to build - total of 5 ICs (plus anything you want to add as interfaces)

Most of the software mentioned above already has good documentation (they were products my company sold)... but if there is interest, I'll document exactly how the board goes together, how everything works and should be used with it, and notes on the software specific to this board.

FWIW, you can "play" with it and try out the software in it's ROM without having to actually build anything - It all runs under my EMILY52 simulator (and in fact this is mainly how I'm testing all the stuff)