Commodore 1541 inter-drive file copy: reality or myth?

Years and years ago, I was following a discussion about Commodore’s 1541 drive and its programmability. Back then somebody claimed that two 1541 drives can be instructed to communicate to each other, e.g. to copy a file from one to another, without intervention of a host computer, beyond the initial setup stage.

Now, I can certainly envisage this being possible with custom drive code running in at least one drive, however, using exclusively the standard serial protocol and ROM code it seems unlikely to me that there’s any truth to such claim.

The reason I am wondering is that I plan to build a new command-line application called iechost-copy that will be able to copy files from one drive to the host computer, and the other way around, or from one drive to another, as long as they use different device numbers. The latter scenario seems to always involve transmission to a host first, whether a file is first fully read in and then written to, or read and written byte-by-byte.

If anybody has any information about the two-drive file copy without host intervention claim, feel free to comment! I don’t require working code, but just a summary of how that would be done in practice.

About Luigi Di Fraia

I am a Senior DevOps Engineer so I get to work with the latest technologies and open-source software. However, in my private time I enjoy retro-computing.
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2 Responses to Commodore 1541 inter-drive file copy: reality or myth?

  1. silverdrs says:

    It’s been decades ago but I recall a commercial product that allowed two drives to copy disks between them, once initialised by the host computer of course. Also – you can probably (DISCLAIMER: didn’t do any thorough checking) use ROM code but not on the I/O level but rather on the IEC level (LISTN, TLK, etc. rather than CHRIN. CHROUT and Co.) to achieve this kind of functionality. Last but not least for a reasonable speed you will probably want to use custom communication code anyway.

  2. Andy says:

    Maverick use a direct dual copy for whole disks, the filecopy is “normal” one drive at one time…

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