Vector took the Micropolis S-100 board
and relabeled it with their logo. Here is a Micropolis 5 1/4" FDC board.
Vector Graphic Micropolis Floppy
Very early on in the S-100 era, Vector
Graphic made a decision to go with hard sectored floppy disks. They joined up
with a company called Micropolis who were one of the first to make floppy disk
drives available to the S-100 community. The only other significant hard
sectored disk system at that time was the popular Northstar disk controller
system. However over time the soft sectored disks (1 index hole per disk
instead of 16) won out. Thanks mainly to the reliability and flexibility of the
Western Digital controller chips. and the common adaption of CP/M to the format.
In the end even Vector switched over (see
The controller contains the following major functional
Control logic to interpret CPU selection and respond to CPU commands.
A sector separator that separates sector and index pulses and keeps track of
each sector as it passes under the read/write head. Write logic that converts
parallel-form bytes from the CPU to serial data suitable for recording on the
Read logic that converts the serial data from the disk to parallel-form bytes
for transfer to the CPU.
Bootstrap PROMs for reading sector zero of the system disk into RAM, then
starting the program in RAM.
Disk Data Format
Data is recorded on the disk in concentric tracks. The outermost track is track
zero. Each track is divided into 16 sectors. The beginning of each sector is
indicated by a sector hole punched in the disk. An index hole is located halfway
between the holes for sector 15 and sector zero. The sector and the index hole
are sensed by a photo transistor in the disk drive. Each disk sector consists of
a preamble, sync byte, header, data, a checksum, and a post amble. Details are
described in the manual.
The normal controller base address was C000H-FC00H but the board could be
jumpered to any 1K boundary. This was a large bite the 64K available address
You can find out more about this board
from the manual here.
Other Vector Graphic S-100 Boards
Dual FD-HD Controller
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