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 ?