Floppy Disk Interface - DIGITAL-LOGIC MICROSPACE MSEBX800 User Manual

DIGITAL-LOGIC AG
5.2.4.

Floppy Disk Interface

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 DEL or F2 at bootup time.
Floppy Interface Connector
The table shows the pin-out and signal definitions of the board's floppy disk interface connector. It is
identical in pin-out 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 26pin high density (1mm pitch
FCC) connector has only one drive and motor select. The onboard jumper defines the drive A: or B:.
Default is always A:.
Floppy Disk Interface Technology
Only CMOS drives are supported. This means the termination resistors are 1 KOhm and 5 1/4"-drives
are not recommended (TTL interface).
The 26pin connector:
Floppy Disk Interface Connector
FD26: Pin Signal Name
1 VCC
2 IDX
3 VCC
4 DS2
5 VCC
6 DCHG
10 MO2
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 Data rate
80 500 KHz
80 250 KHz
80 500 KHz
FFC/FPC 0.3mm thick 1.0mm (0.039") pitch (MOLEX 52030 Series)
Function
+5Volt
Index Pulse
+5Volt
Drive Select 2
+5Volt
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
34
MSEBX800/900 Detailed Manual V1.0
DOS version
3.0 - 6.22
3.2 - 6.22
3.3 - 6.22
in/out
in
out
in
out
out
out
out
out
in
in
in
out