(34W IDC connector for floppy drive)

Spectrum +3 External FDD Interface: (1)				Amstrad 3" model FD-1 FDD: (2)
Direction	34w Edge Connector (3)	34w IDC Connector	Description	Description	26w IDC Connector	Direction
IN	B1	34	/READY	/READY	25	OUT
-	T2	33	Signal Ground	Signal Ground	26	-
OUT	B3	32	/SIDE 1 SELECT	/??? (4)	23	IN?
-	T4	31	Signal Ground	Signal Ground	24	-
IN	B5	30	/READ DATA	/READ DATA	21	OUT
-	T6	29	Signal Ground	Signal Ground	22	-
IN	B7	28	/WRITE PROTECT	/WRITE PROTECT	19	OUT
-	T8	27	Signal Ground	Signal Ground	20	-
IN	B9	26	/TRACK 0	/TRACK 00	17	OUT
-	T10	25	Signal Ground	Signal Ground	18	-
OUT	B11	24	/WRITE GATE	/WRITE GATE	15	IN
-	T12	23	Signal Ground	Signal Ground	16	-
OUT	B13	22	/WRITE DATA	/WRITE DATA	13	IN
-	T14	21	Signal Ground	Signal Ground	14	-
OUT	B15	20	/STEP	/STEP	11	IN
-	T16	19	Signal Ground	Signal Ground	12	-
OUT	B17	18	/DIRECTION SELECT	/DIRECTION SELECT	9	IN
-	T18	17	Signal Ground	Signal Ground	10	-
OUT	B19	16	/MOTOR ON	/MOTOR ON	7	IN
-	T20	15	Signal Ground	Signal Ground	8	-
-	B21	14	Not Used (NC)	-	-	-
-	T22	13	Signal Ground	-	-	-
OUT	B23	12	/DRIVE SELECT 1	NC?	5	-
-	T24	11	Signal Ground	Signal Ground	6	-
-	B25	10	Not Used (NC)	/DRIVE SELECT 0	3	IN
-	T26	9	Signal Ground	Signal Ground	4	-
IN	B27	8	/INDEX	/INDEX	1	OUT
-	T28	7	Signal Ground	Signal Ground	2	-
-	B29	6	Not Used (NC)	-	-	-
-	T30	5	Signal Ground	-	-	-
-	B31	4	Not Used (NC)	-	-	-
-	T32	3	Signal Ground	-	-	-
-	B33	2	Not Used (NC)	-	-	-
-	T34	1	Signal Ground	-	-	-

(1) From Spectrum +3 Manual
(2) By inspection of hardware: Drive is equivalent to a PCW8256/8512 "A" drive
(3) B=Bottom row, T=Top row
(4) Possibly not used as the drive is single-sided