Small 8- and 16-bit microprocessors make up the bulk of processor shipments. Memory capacity and performance in this space is growing, increasing the need for compact RTOS solutions such as those examined this month.
Chips like the 8-bit parts in Motorola's HC12 series and Cygnal's 1000-MIPS C8051F120 can easily accommodate multiple tasks. While you can write your own RTOS for a job, it's not so easy. Design and implementation are only the first steps. Debugging and maintenance are more important in the long run. This time takes resources away from application development, so consider the long-range implications before rolling your own.
An RTOS, and even a C compiler, can be overkill for an 8-bit PIC with just a few kbytes of flash, in which case Microchip's new MPLAB ICD will be of interest. I found it to be quite handy and easy to use. It takes advantage of the new in-circuit debug capability in Microchip's latest PIC18Fxxx chips and is similar to the Parallax SX-Key for Ubicom's SX microcontrollers. These devices only need a serial port and provide limited breakpoint support. Check them out.