Compaq SLT/286 Floppy Connector Pinout

[KaosEngineer]

As the title mentions, does have the pinout for the floppy connector? It's non-standard and even different than other 26-pin 3.5" floppy pinouts I've found elsewhere.

Pins 1,3,5,7,9,11,13,15 are all ground, and pin 18 and 21 are Vcc (5Vdc). Other 26-pin floppy drives have 1,3,5 Vcc (5Vdc).

Citizen OSDA 53B - discontinued ages ago no info found thus far on any Internet archives

what a couple of us have determined (may be in error) is as follows:

01=GND					02=/STEP
03=GND					04=/WDATA
05=GND					06=/WGATE
07=GND					08=/TRK0
09=GND(no pin)				10=/WPROT
11=GND					12=/RDATA
13=GND					14=/HDSEL
15=GND					16=/DSKCHG
17=/RPM_LC-H/L				18=VCC (5Vdc)
19=/DENSITY_SELECT			20=/INDEX
21=VCC (5Vdc)				22=/DIR
23=???					24=/DRV1 ??? 
25=???					26=/MED1 ???

Drive connector 23-26 connect to a Fujitsu Compaq date code 9014 part number 114390-001 (I think it's a gate array 4x30 pins) QFP chip's pins 13, 2, 3 and 13 respectively.

Thanks for any assistance,
KaosEngineer

 

[T-Squared]

Is it different even compared to the connector found in the large black T-#### series of Toshiba portable computers?

 

[Thermalwrong]

I'm a little late but since this seems to be the only thread discussing the OSDA-53B pinout I think it should go here.
I have been trying to hook up a regular laptop floppy drive to the Compaq LTE Lite laptops and found that connecting all the signals up directly is resulting in damaged drives, it does work though! Your pinout listed here was instrumental in me hooking a regular Teac FD05HG floppy in place of the Citizen VIDA-15B drive and it did work with 1.44MB floppies but when I tried a 720K disk the drive broke and will now only read DD disks not HD.

So a couple of years ago I got a Compaq OSDA-53B desktop floppy drive which had an adapter board attached to connect it up to a standard 34-pin edge connector type floppy cable - here are the results (whether or not signals are active_low is not :
1 GROUND
2 STEP
3 GROUND
4 WRITE_DATA
5 GROUND
6 WRITE_GATE
7 GROUND
8 TRACK_0 (VIA 7407 & 2.7K 5V PULL-UP)
9 N/C
10 WRITE_PROTECT (VIA 7407)
11 GROUND
12 READ_DATA (VIA 7407 & 2.7K 5V PULL-UP)
13 GROUND
14 HEAD_SELECT
15 N/C
16 DISK_CHANGE (VIA 7407 & 2.7K 5V PULL-UP)
17 DENSITY_SEL
18 5 VOLTS
19 MEDIA (VIA 7407 & 2.7K 5V PULL-UP + JUMPER AT EDGE CONNECTOR)
20 INDEX (VIA 7407 & 2.7K 5V PULL-UP)
21 5 VOLTS
22 DIRECTION
23 N/C (SHOULD BE DRV_SEL_A BUT IS NOT ROUTED)
24 DRV_SEL_B
25 MOTOR_EN_A
26 MOTOR_EN_B

The output signals from the floppy drive go through a 7407 before being output to the 34-pin floppy cable. The pinout matches up with what's listed here: https://eab.abime.net/showthread.php?p=1442154
But the handling of some of the signals is useful to me and the MOTOR and DRIVE select signals could be useful to someone

 

[Thermalwrong]

And now my adapter board works with both DD and HD disks, simply unhook the MEDIA and DENSITY_SEL lines and it all behaves. Excellent