Fdc-To-Disc Drive Interface - HP Vectra Reference Manual

Foe
Data Register
This is a bidirectional register. Write Function: 8-bit data is written
to FDC chip as commands via programmed I/O and write data
during disc transfers via DMA.
Read Function: 8-bit data is read from FDC chip as result of
commands via programmed I/O and read data during disc
transfers via DMA.
Digital Input Register
Bit Data
7
Definiton
State of the disc change line. Becomes active when
the drive door is opened and at power-on. It will
remain active until reset when a step pulse is issued.
It is active high.
FDC-to-Disc Drive Interface
The 5 1/4 inch disc drive interface with the controller is through
control signals, status signals and data signals. The 5 1/4 inch
drives are daisy-chained on one connector and cable. The
following table shows the pin assignments for the 34-pin
connector. The input or output of the signals are referenced to
the processor board.
In the HP Vectra system the HP45812A 1.2 MB Internal Flexible
Disc Drive provides a - DISC CHG signal on the drive interface pin
34. This signal indicates the detection of the drive door being
opened. The HP45811 A 360 KB Internal Flexible Disc Drive does
not provide a - DISC CHG signal on pin 34. Thus, this signal will
always be inactive and the system cannot detect a possible media
Processor Board 49