Buster 11 is required for ZORRO III cards to manipulate Multiple DMA Channels correctly. No way will an A4091 or Z3 Fastlane SCSI card work in a ZORRO III miggy with Buster 9. It will fall over & lock up on the SCSI Bus when another DMA channel is called. I lived this one & had my very first A4KD upgraded by WANG. They were responsible for C= Home Warranties in 1992 until their demise in April '94.
When the service guy came to replace Buster 9 with an 11, I got a complete Mobo swap out as mine was surface mounted Rev 9.
Not O.T. but, ....heh, ....through the WANG Engineer, I also scored a very cheap A3640 which Over-Clocked to 33Mhz.
There were some issues with C= upgrading Buster09 to 11 & the A3640 processor cards going from Rev 3.0 to 3.1 & finally Rev 3.2. This all happened at the same time. With GAL Chip U209 showing a -03 for Rev 3.2, -02 for a Rev 3.1 & -01 for a Rev 3.0. This DMA cock-up did not go down well with Old Skool Amiga fans from the A3000 days, along with the fact you had to have an A4KT to get on-board SCSI. :|
I'm digressing, but it's all part & parcel of the whole she-bang. Buster always was a pain in the ass of all the Amiga Custom Chips. Anyway, slap a Rev 11 Buster in your A4KD & you have multiple ZORRO III DMA channels waiting to be used.
My i7 4.2Ghz X58 monster has one DMA channel. :|
Kin