This section provides information about the 8051 derivatives that C51 directly supports. A number of 8051 derivatives are available that, while remaining compatible, provide deviations from the 8051 architecture in the form of more data pointers, very fast math operations, or reduced instruction sets. For example:
Siemens 80C517 and 80C537 (high-speed 32-bit and 16-bit binary arithmetic operations, 8 data pointers).
AMD 80C521 (2 data pointers).
Phillips/Signetics 8xC751 (maximum code space of 2KB, no LCALL or LJMP instructions, 64 bytes internal, no external data memory).
C51 provides support for these CPUs through the use of special libraries, library routines, and command-line directives such as MODAMD and MOD517. These directives enable C51 to generate object code that takes advantage of the enhancements mentioned above. Refer to the “Compiling with C51” chapter for more information about these directives.