Floppy Disk Interface - DIGITAL-LOGIC MICROSPACE PC/104 Technical User's Manual

DIGITAL-LOGIC AG
4.3.5

Floppy Disk Interface

The onboard floppy disk controller and ROM-BIOS support one or two floppy disk drives in any of the
standard PC-DOS and MS-DOS formats shown in the table .
Supported floppy formats
Capacity Drive size
1.2 MB 5-1/4"
720 K 3-1/2"
1.44 M 3-1/2"
Floppy interface configuration
The desired configuration of floppy drives (number and type) must be properly initialized in the board's
CMOS - configuration memory. This is generally done using ALT + 'S' or F2 at bootup time.
Floppy interface connector
The table shows the pinout and signal definitions of the board's floppy disk interface connector. It is
identical in pinout to the floppy connector of a standard AT. Note that, as in a standard PC or AT, both
floppy drives are jumpered to the same drive select: as the 'second' drive. The drives are uniquely se-
lected as a result of a swapping of a group of seven wires (conductors 10-16) that must be in the cable
between the two drives. The seven-wire swap goes between the computer board and drive 'A'; the
wires to drive 'B' are unswapped (or swapped a second time). The 26 pin high density (1mm pitch
FCC) connector has only one drive and motor select. The onboard jumper defines the drive letter A: or
B:. Default is always A:.
Floppy disk interface technology
We support only CMOS drives. That means that the termination resistors are 1 K ohm. 5 1/4"-drives
are not recommended (TTL interface).
The 26 pin Connector: FFC/FPC 0.3mm thick 1.0mm (0.039") pitch (MOLEX 52030 Serie)
Tracks Data rate
80 500 KHz
80 250 KHz
80 500 KHz
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MSM486V Manual V3.22
DOS version
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3.3 - 6.22