HardFrame is compatible with 2620s. The problem is with ANY DMA device and
(as I understand it) ANY accelerator board. It is caused by a pokey rise in
the AS* line and can be fixed "fairly easily" by a minor mod to the
motherboard (adding a pull-up resistor to a chip). By the way, even the
2090 controller (CBM's own) has this problem. If you want implementation
details, give me a shout.