A modification of the original Intel Basic52 is presented here, modified for the 89C51RD2 series of microcontrollers (mcu).
New (11/2006): Version 1.4beta4 available - check out the changelog!

Having 64kB FLASH and up to 1.75kB of internal RAM (XRAM), this interpreted Basic is able to run on this chip alone, not requiring external components (except reset, power management, Xtal and level converter for RS232).

To fully exploit the enhancements, the modification is primarily intended for the Temic/Atmel variety of the RD2-family.

Contrary to other modifications, this is just a slight modification of the original, just to enable to use it on the RD2 family; hence no extra commands have been added so far, only the syntax of some of the commands has been extended. This means, that the numerous extensions to the original can be hopefully still used (although they need to be remapped).


  • uses internal XRAM
  • programmed directly in FLASH (big programs possible)
  • extended GOSUB syntax, enabling libraries
  • 2x mode switching supported
  • internal EEPROM access supported (where appropriate)
  • all ports can be accessed

For further details, read the List of modifications.


On motivation, reasons etc. read here.


Provided as-is, no liability, fittness for purpose etc.etc. May contain bugs.


This is a reportware. Please, report to the address given below, if satisfied, unsatisfied; let know, if it works or not.

Download here. Download also some example basic BASIC programs here.


Use any general-purpose board with T89C51RD2/AT89C51RD2/AT89C51ED2 and RS232. Download hexfile using e.g. FLIP or similar, don't set any lock. Connect serial cable, start a terminal program. Press SPACE. Try typing in some of the sample programs (not the lunar lander - that is too long and has to be programmed directly to FLASH - read the description of changes) and RUN.

Assuming, you have read the list of changes (link above) and the original manual (e.g. from here).


  • Byte/Word types?
  • Direct EEPROM variables
  • Direct SFR access
  • Buffered serial, maybe with second soft-serial added
  • ADuC 83x/84x support
  • P89V51RD2/P89C668 support
  • AUTO (automatic numbering), RENUM (renumbering)
  • full screen editor
  • inline assembler

Any other idea? Although not very probable that any of these will be completed in a reasonable time, please, write.




Address them to basic_at_efton_dot_sk. Thanks.