CBM B128-80 with Fast Bus installed to allow a person to switch from a serial-type disk driveand an IEEE drive. In this case I am switching between a CBM 8050 IEEE-type drive, and a VIC 1541 serial drive (on top of the monitor). Click for larger view.
A closeup of the two required components of a Commodore B Series "Fast Bus" system. On top of the B-128 is the Serial Bus Interface converter box. This is the device that switches betweem serial and IEEE drives. A RAM expansion cartridge is installed into the B128, in this case a new 24K RAM cart in bank 15 ($2000-7FFF) and handles the serial bus RAM space. The original carts covered $2000-2FFF (not pictured). The Fast Bus program is loaded from diskette on the 8050. (CBUG 84). Click for larger view.
Closeup of the B-128 Serial Bus Interface, which allows a person to toggle between a serial drive and an IEEE drive, or reset the serial port. Click for larger view.