Zenith H-100 - Page 29

10-82
The H-207 is a floppy disk controller board. It functions
as an intelligent interface between the CPU and the disk
drives. The H-207 selects the correct drive in a
multi-drive system and properly handles data transfer to
and from the disk drives.
The H-207 operates as a slave processor. This means the
disk controller board contains its own processor which is
controlled by the master CPU. Thus, the disk controller
board takes commands from the master CPU and converts them
into the necessary signals required to control the drives.
This type of system allows the master CPU to do other tasks
while the disk controller board processor actually does
the work of controlling the disk drives.
The H-207 is versatile. It can support up to four 5-1/4"
and four 8" disk drives. User software selects the type
of drive used and the density of the media. However,
present Heath Company software limits the number of drives
to three.
The H-207 can be operated in three different modes; Wait
State, Polled I/O, or Interrupt. This allows the disk
controller board to support almost all available
so ft-sectored disk formats. By using the Wait State mode,
the board can be jumpered to operate at speeds up to 6 MHz.
Because the H-207 is a IEEE 696 Standard S-100 compatible
card, it can be installed in other makes of computers using
the IEEE Standard. Additional features that make the
controller board acceptable to other computers are: user
selectable addressing, software controllable formatting,
Shugart compatible 8" interface, and adjustable
precompensation.
The in formation provided in this section of the manual will
familiarize you with the operation and troubleshooting of
the H-207. Using this information, you will be able to
troubleshoot the disk controller board to the component
level.
5-113