Graphic Dual-Mode Floppy & Hard Disk Controller Board
This was both a
floppy disk and hard disk controller all on one S-100 board.
There was circuitry for 5 or 10 Mbyte (Seagate) hard disks as well as the
controller for Tandon double sided double density hard sectored floppy drives.
The board could be used as a floppy only controller. The 8 inch FD-HD controller
for the 40 Mbyte drives was very similar to this board.
"dual mode" floppy & hard disk controller had its own RAM, which was accessed
through a control port. This provided high speed loading and unloading of data
to and from the floppy & hard disks. Board control and status, were each
accessed through two 8-bit register data ports. After the board receives the
control signals and data in the correct format, it automatically sequence the
physical reading or writing of the disks.
The board had built in hardware to generated Error Correction Code (ECC) of the
data. Write pre-compensation for disks that needed it was also an option.
It was quite a creative accomplishment at the time putting on one board what
took others two boards to do. Unfortunately the floppy disks had to be hard
The schematic for the board can be
I cannot locate a manual. If somebody can donate a pdf file
will put it here for others.
Other Vector Graphic S-100 Boards
Dual FD-HD Controller
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