The SWTPC S/09 system was the second computer of the brand based on the Motorola 6809 microprocessor, said to be the most powerful 8-bits general purpose MPU available.
As with the first 6809 version, it used the SS-50 version bus. The S/O9 system had a 20-bit adress bus. It was able to address up to 768 Kb. of memory and used dynamic address translation to map 4K pages into the 64K address space of the microprocessor.
The system could be used as a multi-user/multitasking platform. It was delivered with optional operating systems: S/09, Pascal or Basic, and later OS-9 and Flex allowing the system to operate simultaneously with several terminals. Assembler, editor and debug tools were also available.
Three disk options were available, dual 5" floppy drive (2 x 175 KB), dual 8" floppy drives (2 x 1.2 MB) and a 16 MB hard disk. Disk controller as well as printer and RS232 interfaces were provided on appropriate I/O cards.
R. W. Anderson reports:
My old SWTPC has an IDE interface and an IDE HD with 96 partitions of 16
megabytes each (the maximum size that can be supported by the FLEX operating
Hardware and software design of the IDE interface was a colaboration of members of the FUG, Flex User Group.