Commodore 64 has a known bug which doesn't allow to use tape drive together with a 1581 drive.

Basically, in C64 the SRQ (Serial ReQuest) line is connected between IEC bus, CIA chip and the tape drive, burst mode drives (such as 1581) hang when both device in question and tape drive are connected. The bug does not affect older drives such as 1541 or 1571.

C128 has this bug fixed.

Is there any hardware fix that can resolve the problem in C64 ?

  • Can you add details about the bug (such as what code causes the problem)?
    – user3169
    Commented Jun 9, 2016 at 17:37

1 Answer 1


From a quick search, it sounds like the quickest way to solve it is to update the 1581's ROM (see this thread on Lemon64) - either by buying JiffyDOS, or finding the newer version of Commodore's own firmware (such as from this page).

  • For what it's worth - I've never actually had that issue on my own C64 + 1541 Ultimate + 1581 combo - makes me wonder if it's got the newer firmware (and if there's ways to confirm the version).
    – robc
    Commented Jun 9, 2016 at 5:28
  • that's because 1541Ultimate is NOT a tape drive. The problem seems to be with SRQ line shared between IEC and tape drive signals. Commented Jun 14, 2016 at 4:20

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