USB FDD@1306 USB floppy adapter

USB_FDD@1306

Front of board

This is an adapter for using full-size 3.5" floppy drives as USB floppy drives. It uses an unknown 24-pin TSOP/TSSOP? microcontroller. The chip has "6520" on the underside. The oscillator on the board is 12 mhz.

Desoldered board

Rear of board

Underside of chip

Chip pinout

C4?	1	24	DIRECTION
LED?	2	23	VCC +5v
R3	3	22	N/C
Drive Select	4	21	N/C
Motor On	5	20	Wgate
C3?	6	19	Write Protect
USB Data+	7	18	Track 0
USB Data-	8	17	DiskChange
RDATA	9	16	Index
WDATE	10	15	HeadSelect
VSS	11	14	STEP
OSC1	12	13	OSC2

Note: It seems to use the sorta-compatible Shugart interface, as it uses pin 6 which is N/C in the IBM format.

for "Drive Select" it's hooked up to DS1/DS2/DS3/DS4.

Functionality

I have an identical (presumably: I need to open my case up and double-check) unit installed in my main PC. It identifies itself to windows as "TEAC USB UF000x USB Device", VID=0644 PID=0000.

Links

• Floppy drive connector pinout
• ebay auction where I bought this, on 12/28/2018