Code Probe 2.1

Code Probe 2.1 — a lightweight machine language monitor for the Commodore 64.

Code Probe is a software-based alternative to hardware cartridge monitors. It lets you inspect and modify memory, manage CPU registers, fill and transfer memory regions, save and load files, and execute machine language programs directly on the machine. Originally written for the Commodore VIC-20 in 1990 and later ported to the C64.

Getting started

Load Code Probe into memory at $C000 and start it:

LOAD "CODEPROBE",8,1
SYS 49152

Command summary

Command	Action
D <start> <end>	Hex dump a memory range
A <address>	Alter mode — write bytes to memory
R	Display registers
R <reg> <value>	Set a register and display
RF	Display registers with flag bit-view
RF <flag> <bit>	Set a flag bit and display
F <address> <count> <value>	Fill a memory range with a byte value
T <source> <count> <dest>	Transfer a memory range to a new location
S <device> <filename>	Save a memory range to a file
L <device> <filename>	Load a file into memory
G <address>	Execute a machine language program

Downloads

• code-probe-2.1.d64 — bootable disk image for emulators and real hardware.
• codeprobe.prg — ready-to-run C64 binary (loads at $C000).
• Source code (zip / tar.gz) — 6502 assembly source, the rendered user manual (docs/user-manual.pdf), and demo images.

See the bundled user manual (docs/user-manual.pdf) for full documentation.