thad@cup.portal.com (Thad P Floryan) (01/27/91)
wilber@alice.att.com (rew) in <11813@alice.att.com> writes:
Could someone mail or post a brief description of what each of the
signals on the 34 conductor disk cable does? I want to have some
notion of what I ought to be seeing when I do a recal. This is
probably worth posting, since other people are bound to have similar
problems when they attack the motherboard in the quest for a bigger
bucket of bits.
Ask and ye shall receive! :-)
The Signals on the 34-pin cable are fairly standard, but note that OLDER drives
use pin 2 for write pre-comp (actually pre-distortion). The pinnings for the
20-pin cable are from a Maxtor OEM manual which has some other options; the
only signals really used are the GNDs and the MFM Read/Write Data lines.
For the 34-wire daisy-chained cable:
GND RTN SIGNAL Signal
PIN PIN Name
------- ----- ------------
1 2 - Head Select 2^3
3 4 - Head Select 2^2
5 6 - Write Gate
7 8 - Seek Complete
9 10 - Track 0
11 12 - Write Fault
13 14 - Head Select 2^0
15 16 (reserved)
17 18 - Head Select 2^1
19 20 - Index
21 22 - Ready
23 24 - Step
25 26 - Drive Select 1
27 28 - Drive Select 2
29 30 - Drive Select 3
31 32 - Drive Select 4
33 34 - Direction IN
And for the 20-pin radial cable:
2 1 - Drive Selected
4 3 - Remote Write Protect Option
6 5 - Spindle Power Control Option
8 7 (reserved)
10 9 (reserved)
12 11 GND
13 + MFM Write Data
14 - MFM Write Data
16 15 GND
17 + MFM Read Data
18 - MFM Read Data
20 19 GND
One additional comment: I hope you've removed the disk's terminator resistor
pack on the first drive and kept the terminator pack on the LAST drive on the
34-wire daisy-chained cable.
Thad Floryan [ thad@cup.portal.com ]