Floppy Disk Interface - DIGITAL-LOGIC Microspace MSM586SEN Technical User Manual

DIGITAL-LOGIC AG
4.3.4

Floppy Disk Interface

The onboard floppy disk controller and ROM-BIOS support one floppy disk drive 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 by using CTRL / ALT / S 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 selected 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 A:
Floppy Disk Interface Technology
We only support CMOS drives. That means that the termination resistors are 1 kohm. 5 1/4"-drives are not
recommended (TTL interface).
The 26 pin connector:
Floppy Disk Interface Connector
FD26: Pin Signal Name
1 VCC
2 IDX
3 VCC
4 DS2
5 VCC
6 DCHG
10 M02
12 DIRC
14 STEP
16 WD
17 GND
18 WE
19 GND
20 TRKO
21 GND
22 WP
23 GND
24 RDD
25 GND
26 HS
Tracks
80
80
80
FFC/FPC 0.3mm thick 1.0mm (0.039") pitch (MOLEX 52030 Serie)
Function
+5 volts
Index Pulse
+5 volts
Drive Select 2
+5 volts
Disk Change
Motor On 2
Direction Select
Step
Write Data
Signal grounds
Write Enable
Signal grounds
Track 0
Signal grounds
Write Protect
Signal grounds
Read Data
Signal grounds
Head Select
MSM586SEN/SEV Manual V1.5E
Data rate DOS version
500 KHz 3.0 - 6.22
250 KHz 3.2 - 6.22
500 KHz 3.3 - 6.22
in/out
33
in
out
in
out
out
out
out
out
in
in
in
out