CompuPro - Disk 1A
The Disk 1A was as you might expect an upgrade of the original Disk 1. It still used an Intel  8272 or NEC 765A floppy disk controller instead of a at the time, then more common Western Digital 1791-7 chips. Unlike the Disk 1 it did not have on board a basic serial I/O port to boot the system for the first time. Instead the CompuPro boot software assumed your consol was connected to their System Support 1 board or their Interfacer 4 board.

What was interesting about both the Disk1 and 1A was that the boot ROM had code which via a switch selection could be used to work with either a 8085/Z80, a 8088/8086/80286, a 68000 or a 32016 CPU based system. The board handled data transfers via 24 bit DMA with the ability to cross 64K boundaries.  There was a priority arbitration scheme for the on-board DMA circuitry that will allow up to 16 temporary bus masters to operate without conflict.  There was an advanced digital data separator for reliable data transfers. No cap or resistor adjustments were required. The board had provisions for running both 5.25" and 8" floppy drives at the same time.
 
The manual for this board can be obtained here.