Amiga 2000 Buster tower (Commodore 1986)
The A2000 Buster is based on the PAL equations of the original German A2000 bus controller logic. The Buster tower fixes a buffer direction bug in the first production run of the Buster (318075-01) chips.
The German PALs contained a bug which did not allow the buffers between the 68000 bus and the Zorro bus to point away from the Zorro bus when a Zorro bus master talked to another Zorro bus target.
In Germany, it was fixed by a replacement PAL, but that PAL needed to be combined with the initial MOS Buster vhip on tower' adapter PCB.
The later MOS/CSG 5721 318075-02 revision of Buster contained the missing logic, and is the recommended component to use.