If you want interrupt routines in 8051 assembler language there are also nice ones in this file at this location that I wrote as a part of a FLASH loader for a Cygnal C8051F126. The file also contains packet communications routines with CRC support.

It will require a small bit of tweaking to work on other 8051 variants as the Cygnal uses some different SFR addresses. The 'F126 also has SFR paging since there are way over 256 SFRs so that would also have to be removed.

This code in nice for small applications since it is all in assembler, the UART queues are in local RAM (but coded in a way that they can slide up into the PDATA space above 0x80 address). It is also coded to allow the serial interrupt queue pointers to be variable in size as long as you use values like 4, 8, 16, 32, 64 bytes for the size of the buffers.

Michael Karas