Home » GRC TBC QBUS Board

The “GRC TBC” is a bootstrap and terminator board designed for PDP-11 QBUS systems.

The manufacturer is General Robotics Corporation.

The TBC provides the following functionality:

  • Termination for QBUS backplane signals
  • On-board EPROMs (for bootstrap or other purposes)
  • Support for front-panel functionality (run status indicator, enable/halt switch and LTC switch)
  • Capability to generate LTC signal from external AC transformer

According to the User’s Manual, GRC made available a range of bootstrap EPROMs for this board (including support for RX02 and RL drives). I have one set of EPROMs for this board. I don’t yet know which device these support, but I have inserted links to them below.


GRC TBC User’s Manual

EPROM marked “TBC 1 Hi”

EPROM marked “TBC 1 Lo”

I have also found the following documentation (which appears likely to be earlier than the Users Manual mentioned above):

GRC TBC-11 Specifications

GRC TBC-11 Schematic

TBC Hard Bootstrap for Cartridge Disk and RX01 Floppy