ACT apricot - Introduction

FLOPPY DISK INTERFACE
INTRODUCTION
The Floppy Disk Interface is located on the System Board
and consists of
the elements of circuitry as illustrated on
the block diagram opposite. The interface provides all the
control functions necessary for formatting and transferring
data
to/from the MicroFloppy Disks via the system disk
drivels).
The configuration of the interface incorporates all the
necessary facilities to control either single or dual
MicroFloppy
Disk Drive systems, operating with either
single or double-sided disks.
All disks,
whether single or double-sided, are soft-
sectored
and encoded with the same disk format. This
format is logically developed from the IBM system 34
format (a standard format for 8 inch disks), and is
specifically designed
to obtain the optimum number of data
bytes
-on a 3.5 inch MicroFloppy disk. The format employs
double
density MFM coding with 512 bytes per sector and 9
sectors per track.
The number of tracks per side of disk is
solely a
function of the version of disk drive, and may be
either 70 or 80.
A brief description of the disk format is included at the
end of this section (under the heading TRACK FORMAT).
This should be read now, if the reader is unfamiliar with the
method of recording data on disks.
Control connections between the interface and the
drivels) are all made internally within the System Unit. The
Floppy Disk Drive Connector is a 26-way male IDC
terminal mounted on the component side of the System
Board. An associated ribbon cable assembly links the
interface to the drivels).
Regulated power supply voltages for the disk drives are
supplied directly
from the System Board. Separate. power
supply
connections are provided for each disk drive, using
Molex
connectors (mounted on the component side of the
Sys~em Board) and 4-wire cable assemblies.