Mitsubishi Electric M4853 Maintenance Manual page 26

Non-standard modes of operation are available to the customer by
using option plugs,
plug, installing the option plug on a pair of square pins is a
short" condition, and removing it is an "open".
soldered wire jumper between two pad3 is a "short", and none is a
"open".
The specific options are explained below.
7.1 DSO to DS3
When two or more PDDs are connected to the system,
jumper one of the four choices to allow the drive to be
enabled when the particular select line is taken to a,
logical "0" condition.
Only one drive per system may be designated for each
drive number.
drive "0", etc., in a system.
7.2 MX
If only one FDD- is in a system, this option may be used
to constantly select the drive.
ignore the status of the "DS" lines.
This jumper must be removed in multi-drive systems.
7.3 HS
This plug is installed to cause the heads to load when
the drive is selected by DSO through DS3.
after the drive is "ready" (see section 7.3).
install HM or HC with this option.
7.4 HM
This plug is installed to cause the heads to load when
the motor on line (P-l-15) is brought to a logical "0"
level.
section 7.3).
option.
7.5 HC
This plug is installed to cause a constant head load
condition which occurs after the drive is "ready" (see
section 7.3) to allow for proper seating of the
disk.
7.0 USER OPTIONS
and some PCB cut and/or jumpers.
In other words, there can only be one
This occurs after the drive is "ready"
Do not i nstall HS or HC with
Do not install HS or HM with this option.
When using
A trace or a
It causes the drive to
This occurs
Do not
(see
this
f l o p p y