User manual for the PEPBUG debug monitor built into the Fairchild F38T56 power supply.
The PEPBUG Debug Monitor provides an interactive debugging environment for F8 or F387X programs running on the Fairchild F38T56 power supply. It can be accessed via a teletype terminal or a 4 × 6 keypad and allows inspection and modification of memory, registers, I/O ports, and program flow.
The manual describes the hardware interface (ports 28h and 29h, timer and interrupt vectors), command set, baud‑rate configuration, and available subroutines. Appendices contain full command reference, port assignments, keyboard/display schematics, and a complete program listing.
| Port A address | 28h |
|---|---|
| Port B address | 29h |
| Local Interrupt Control address | 2Ah |
| Timer address | 2Bh |
| Timer interrupt vector | 0300h |
| External interrupt vector | 0380h |
| Clock frequency used for baud calculations | 2 MHz |
PEPBUG uses RAM locations 2B80h–2BE5h as a save and work area, keeping it out of the user's first 8 KB address space.