SCSI and ST-506 controller

• supports seven SCSI and two ST-506 devices at once
• the SCSI drives are controlled by the WD 33C93 IC
• the ST-506 drives are controlled by the Zilog Z80B CPU
• the 33C93 chip can be controlled by either the 68000 (default) or by the Z80
• DMA transfers are provided by the custom Commodore 8727 IC featuring a 64 byte FIFO buffer
• the Z80 CPU has 2 kB RAM to buffer commands from the Amiga, 8 kB PROM with driver routines and 1 kB RAM for storage of variables
• three autoboot ROMs
• custom bootblock design
• does not support the SCSI Direct protocol
• does not support partitions and drives larger than 256 MB
• the ST-506 interface does not support 16-head drives
• 50 pin internal SCSI connector
• DB25 external connector
• hard disk activity LED connector
• on Zorro III machines the card only works if the driver and all the buffers are loaded into chip RAM
• A-Max II driver (hddisk.amhd)

hard disk kits

• the A2090A was sold in kit form which included the controller itself, a hard disk, cables, installation disk and manual
• A2092: A2090A bundled with a 20 MB Miniscribe 8425 hard disk
• A2094: A2090A bundled with a 45 MB Toshiba MK-134FA or a 46 MB Rodime RO-3055 hard disk
• all of these hard disks are ST-506 drives

drivers & installation