C= commodore 64

Data transfers between Commodores and the outside world

This page is dedicated for the various data transfer systems that are available for Commodore 8-bit computers. There are some utilities that let you read MS-DOS disks with Commodore 64 or 128 and a 1541, 1571 or 1581 disk drive, but the modern way to go is to hook your Commodore to a bigger computer, like the Amiga or a PC compatible.

Wireless (disk-based) transfers

The 1570, 1571 and the 1581 disk drives contain an MFM controller chip that can easily be programmed to read MS-DOS (and CP/M) diskette formats. There are numerous utilities for these drives. Some of these utilities can be found on ftp.funet.fi in /pub/cbm/c64/diskutil.

The 1581 disk drive uses MFM also for its native format, which makes it relatively easy to read and write its disks on an Amiga or PC. For the Amiga, there is Copy1581, and Daniel Fandrich has written a Linux module that reads these disks on a PC.

The 1541 was not intended for anything else than writing (and sometimes reading) the proprietary Commodore Group Code Recording (GCR) format. But thanks to a hack invented by Daniel Fandrich, the 1541 (except the 1541-II) can be modified so that it generates a higher baud rate that is required for reading and writing MFM disks. The 1541-dos package written by Daniel Fandrich and Richard Hable reads single-sided 9-sector 180-kiobyte MFM disks that hold, and it writes files in its own 90-kilobyte format, which can be read with an MS-DOS or *nix program, which are supplied with the package.

Cable-based utilities

A long time ago, the only transfer option you had was an RS-232C cable hooked to an RS-232C adaptor, and a terminal program. Typically, this allowed transfer rates of at most 1200 bits per second. Currently there is one utility, Over5 by Daniel Kahlin that allows transfer rates of 38400 bits per second between an Amiga and a Commodore 64.
Hooking a serial bus disk drive to another computer
Most transfer utilities make use of a parallel connection. On the PC side, the first wave of these utilities was started by X1541, a program that let you hook a 1541 drive to your PC's printer port. The program was full of bugs, and it was never updated, but the X1541 cable became the 'de facto' standard. Nowadays there are several utilities for hooking IEC bus devices to a PC. Check the archive at ftp.funet.fi in /pub/cbm/transfer/1541-to-PC.

For the Amiga, there exist several emulators that can access a disk drive connected to the printer port. One of the best such emulators is Frodo II written by Christian Bauer.

Hooking two computers together
Connecting an 8-bit Commodore to another computer (Amiga or PC) is generally the fastest way to go, because you can use separate handshaking lines and sufficiently many data lines. This kind of utilities existed first for the Amiga and later for the PC compatibles.

Most utilities support only the Commodore 64, but the prlink utility written by me and Olaf Seibert supports most 8-bit Commodores (PET, VIC-20, C64, C16 and C128) and the Amiga and the PC.

Marko Mäkelä (Marko.Makela@HUT.FI)