Re: 1541 – two computers, one drive

From: Jim Brain <brain_at_jbrain.com>
Date: Wed, 25 Mar 2020 19:28:37 -0500
Message-ID: <26998565-564c-27f7-1b6d-65af12f5e6c8_at_jbrain.com>
On 3/25/2020 9:35 AM, silverdr_at_wfmh.org.pl wrote:
> https://www.wikizero.com/en/Commodore_64_peripherals
>
> says:
>
> "It was also possible, without requiring a VIC-switch, to connect two Commodore 64s to one 1541 floppy disk drive to simulate an elementary network, allowing the two computers to share data on a single disk (if the two computers made simultaneous requests, the 1541 handled one while returning an error to the other, which surprised many people who expected the 1541's less-than-stellar drive controller to crash or hang). This functionality also worked with a mixed combination of PET, VIC-20, and other selected Commodore 8-bit computers."
>
> Has anyone tested that? Is that a fully deterministic/reliable behaviour?
>
OK, I tested this.

  * Assuming one has done the poke or otherwise released the lines on
    each machine, a simultaneous request from two machines to a single
    drive does indeed work as stated above.
  * But, the requests must be simultaneous.  If one waits for any amount
    of time between requests from 2 machines, the one returns a "file
    not found" error and the other one hangs.

So, I don't think the above is reasonable advice.

Jim


-- 
Jim Brain
brain_at_jbrain.com
www.jbrain.com
Received on 2020-05-30 01:24:51

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