IBM 770 manual System Board, Signal, I/O and, Feature

Pin	Signal	I/O and	Feature
1	UBAYID1	I
2	UBAYID2	I
3	GND	GND
4	GND	GND
5	-INDEX	I
6	-DRVSEL0	O
7	-DISKCHG	I
8	-DRVID0	I
9	NC	N/C
10	-MEDID0	I
11	-MONTEN0	O
12	DRATE1	O
13	-DIR	O
14	-DRVID1	I
15	-STEP	0
16	GND	GND
17	-WRDATA	O
18	GND	GND
19	-WREN	O
20	-MEDID1	I
21	-TRACK0	I
22	DRATE0	O
23	-WPROTECT	I
24	-RDDATA	I
25	GND	GND
26	-SIDE1SEL	O
27	UBAYID0	O
28	RSTDRV	O
29	GND	GND
30	DD7	I/O
31	DD8	I/O
32	DD6	I/O
33	DD9	I/O
34	GND	GND
35	DD5	I/O
36	DD10	I/O
37	DD4	I/O
38	DD11	I/O
39	VCC5B	VCC
40	VCC5B	VCC
41	VCC5B	VCC
42	VCC5B	VCC
43	DD3	I/O
44	DD12	I/O
45	DD2	I/O
46	DD13	I/O
47	GND	GND
48	DD1	I/O
49	DD14	I/O
50	DD0	I/O
Figure	2-8 (Part 1	of	2). UltraBay II Connector Pin Assignments

System Board 2-13