The most commonly used dialect of BASIC for microcontrollers, Intel’s 8052AH-BASIC, cannot be used as is with the new 8051 derivatives. This article presents a modified version of the interpreter that also supports the 80535/537 microcontrollers. These have been used in recent Elektor projects, such as the 80C537 Single-Board Computer and the 537 ‘Lite’ computer.The Intel BASIC-52 interpreter was originally provided in the form of a mask-programmed microcontroller with the type designation 8052AHBASIC. The interpreter automatically recognises the amount of available RAM and the baud rate of the connected terminal when the system starts up. There are also Autostart functions that allow a program to be run automatically on start-up. It is even possible to program an EPROM in the system, as long as you use the original Intel IC.