What are you talking about?

Every subgroup has its own terms people in the know expect everyone to know. - Everyone knows that … right?

In the wiki is a function active to show a short explanation for certain terms, like what you get when you write C64. - To modify or add those contact Walter.

This page is to try to give some information about terminology used in the Commodore and retro computer community.

File formats

TAP — Raw Tape Image

A byte‑accurate recording of the actual magnetic pulses on a Commodore cassette tape.

PRG — Single Program File

A raw C64 program as it appears in RAM, with a 2‑byte load address at the start.

Key traits:

Contains one program or data block.

Loads instantly in emulators or SD2IEC.

D64 — Disk Image (1541 floppy)

What it is:

A full 170 KB image of a 5.25“ 1541 disk, including directory, sectors, BAM, and filesystem.

Key traits:

Can contain multiple PRGs, data files, and custom loaders

G64

Which is a d64 with additional data to represent low level floppy info. Used for disks with disk based copy protection.

CRT — Cartridge Image (ROM dump) & T64 — Tape Container (simplified tape image)

What it is:

A virtual tape file that stores one or more PRGs, but not the real pulse‑timing of a tape.

Key traits:

Contains a directory of PRGs extracted from a tape.

Does not preserve turbo loaders or custom tape protection.

Loads much faster than a real tape because it skips the pulse‑level detail.

REU

A c64w>RAM Expansion Unit is a hardware device that increases the amount of RAM available to a computer. The C64U has this functionality build in and can be enabled in the menu.

The 8-Bit GUY explains how the REU works on the classic C64

What is border removal?

Border removal exploits VIC-II behavior when $D011 bit 4 is cleared at specific raster lines. This lets demos display sprites and graphics in the border area.