80C51 Based SBC uses Atmel's 89C51

Powerful expandable SBC, based on Atmel's 89C5X .
The easiest SBC to program on the market. Only requires a serial link to your PC to download your program into onboard EEPROM.
No external programming hardware needed, required programming hardware and software included. EEPROM programmer included on SBC.
Fast. Standard 11.09 MHz, call us for information on faster speed units.
Small size. Approximate Size 4.75" X 3.2". Great for embedded control applications.
Completely expandable via stack through bus that accepts up to 7 expansion boards. Use our cards or custom design your own.
RS232 port included, RS485 port option available for networking multiple units.
Interrupt expansion available, expands SBC to 5 external interrupts.
Wide range of RAM and (E)EPROM options available. 2, 8, 32 kb RAM. 2, 8, 16, 32, 64 kb ROM.
Includes Assembler, Basic and C compilers. Manual and Disk have C and Assembly examples. These are shareware/freeware and working demo units that produce hex files that you can download and run directly.
For advanced users, model Flex51EX includes two kilobytes of EEPROM to provide applications with re-writable, non-volatile data storage, 256 bytes of internal RAM, two data pointers which may be used to expedite the transfer of data, a watchdog timer, a Power Off Flag to differentiate between a cold start and a warm start of the SBC and an additional counter/timer channel. Call for more information on the Flex51EX.