[fpc-devel] FPC micro controller

Marco van de Voort marcov at stack.nl
Thu Jul 30 12:15:16 CEST 2009

In our previous episode, Desmond Coertzen said:
> No use for OS, just for smaller MCU's that are bit accessible.

> By application I meant: Is this the correct method to apply a bit-packed
> structure to code?

Note that there are two kinds of bitaccessibility. 

E.g. microchip follows more the bitpacked way, where all SFR are overlayed
(ABSOLUTE in FPC) with a bitpacked union in the header.

In addition some mcu's like IIRC 8051 (*) allows to access ANY integer/byte
value to be accessed using .<bitnr> suffix.  So if b is of type byte, b.7
returns the 7th bit. It also had a special type bit to store these and do
some limited arithmetic on them. Probably mapping directly on some bit sized
registers/flags and instructions.

(*) iirc we had some Hitachi clone 80515 or so. The compiler was the fairly
wellknown Keile one.

More information about the fpc-devel mailing list