The Z-207 was the floppy disk controller board used for all floppy disk IO
with the Z-100 Computer. It functioned as an intelligent interface between
the CPU and the disk drives. The Z-207 selected the correct drive in a
multi-drive system and properly handled the data flow to and from the
drives. The Z-207 operated as a slave processor. This means the disk
controller board contains its own processor which was controlled by the
master CPU. Thus, the disk controller board took commands from the master
CPU and converted them into the necessary signals required to control the
drives. This type of system allowed the master CPU to do other tasks while
the disk controller board processor actually does the work of
controlling the disk drives. The Z-207 was versatile. It
could support up to four 5-1/2" and four 8" disk drives. User software will
selected the type of drive used and the density of the media. However, the
Heath Company software limited the number of drives to three.
The Z-207 could be operate in three different modes; Wait State, Polled I/O,
or Interrupt. This allowed the disk controller board to support almost all
available soft-sectored disk formats. When placed in the H/Z-100, the disk
controller board used the Wait State mode of operation. By using the Wait
State mode, the board could be jumpered to operate at speeds up
to 6 MHz.
Because the Z-207 was a S-100 compatible card, it could be installed in
other makes of computers using the S-100 bus. Additional features that make
the controller board acceptable to other computers are: user selectable
addressing, software controllable formatting, Shugart compatible 8"
interface, and adjustable
pre-compensation. The board utilized the Western Digital 1797 FDC chip
The relevant sections of the Z-100 user manual for this FDC board and drive
can be obtained
here.
