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From: pbauer@ATHENA.MIT.EDU (Paul H Bauer)
Newsgroups: comp.sys.apple2
Subject: Re: 2.5" Drive Connections?
Date: 15 Dec 1994 20:24:24 GMT
Organization: Massachusetts Institute of Technology
Lines: 201
Message-ID: <3cq8lo$t7l@senator-bedfellow.MIT.EDU>
References: <3cko2i$7pa@canopus.cc.umanitoba.ca>
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The following may help answer some of these questions:
Following, please find the pinout table for GoDrive SCSI.
Don't try and use the same +5V (or return) for both motor and logic;
t'would be bad.
I'm not certain that the setup of J2 is the same for, say, a Conner
drive, but J1 should be identical.
In my earlier response to this thread, my brain died.
I said there is no 50 pin connector on the GoDrive.
This is only sort of true. While we think of there being
two connectors, J1 & J2, they're both physically one part.
And if there weren't a bunch of missing pins, together
they'd be like a 50 pin connector.
Pinouts for Quantum GoDrive SCSI:
This is excerpted, sort of, from the
_Go-Drive_40/80S_Product_Manual_,
copyright 1991 by Quantum Corp.
The connector is a single 2 x 25 connector on 2mm centers for power,
data and SCSI device address. The connector also includes four
pins (pins 1-4 of J2) which are reserved as factory test points.
J1 J2
Pin39 Pin1 Pin1
| | /
o o o o o o o o o o o o o o o o o o o o o o o
o o o o o o o o o o o o o o o o o o o o o o o o
| |
Pin40 Pin2
Recommended mating P/N: Dupont 69764-050 or equiv.
To prevent the possibility of incorrect installation, the hole
of the mating ocnnector that corresponds to pin 17 of J1 should
be plugged. Max cable length = 12"
Pins 5-7 of J2 are used for hardware selectable device address as follows:
Pin 5 Pin 6 Pin 7 SCSI id
----- ----- ----- -------
hi hi hi 0
lo hi hi 1
hi lo hi 2
lo lo hi 3
hi hi lo 4
lo hi lo 5
hi lo lo 6
lo lo lo 7
Pin 8 of J2 can be used to drive an LED during periods of drive activity.
Signal Pin Signal Pin
----------- ---- ----------- ----
+5V (logic) 1 +5V (logic) 2
Logic return 3 Logic return 4
GND 5 DB0 6
GND 7 DB1 8
GND 9 DB2 10
GND 11 DB3 12
GND 13 DB4 14
GND 15 DB5 16
KEY 17 DB6 18
GND 19 DB7 20
GND 21 Parity 22
GND 23 Termination Power 24
-ATTN 25 -BSY 26
GND 27 -ACK 28
-RST 29 -MSG 30
GND 31 -SEL 32
-I/O 33 -C/D 34
GND 35 -REQ 36
Motor Return 37 Motor Return 38
+5V (motor) 39 +5V (motor) 40
Everything above is my opinion, not Quantum's.
This seems to be a popular topic, so here's some
more info....
Everything above (and below) is my opinion, not Quantum's.
Power Requirements for GoDrive 80S
Voltage +5V +-5%
Current:
Sleep/Standby 0.04A
Parked (actuator off, spindle on) 0.16A
Idle (track following) 0.34A
Active: Reading/Writing 0.40A
Active: Seeking 0.44A
StartUp (peak) 1.10A
Ripple & Noise 50mV
For a one disk unit (40S, 60S, GRS 80S, GLS 85S),
the peak draw at startup is more like 0.90A.
I am not an expert on termination,
or even on SCSI generally, or on much of anything,
to be honest. But perhaps this info will help.
In testing operations, we use
a little interface board which plugs on to
the GoDrive and presents a standard SCSI ribbon
connector, so that the GoDrive and adapter board
together appear, electrically, to be just like
any 3.5 inch SCSI drive. We have termination
resistor packs on that adapter board, so I
assume that means termination must be done
external to the drive. I�ve never seen inside a
Powerbook (I�m saving my pennies), but I assume
there must be termination built onto the
motherboard.
The GoDrive 40/80 S product manual
(copyright 1991, Quantum Corp., etc)
says the following about Vterm:
GoDrive supplies terminator power through a Schottky
and a 1A fuse:
Vterm=
4.25V DC to 5.25V DC
150 mA min with 1K pullup resistors
800mA min source drive capability, if supplying
external terminators
1.0 mA max sink capability, except when providing
power to an internal terminator
1.0A current limiting (fuse)
I don't pretend to fully understand all the
earth-shattering implications of all those
specs, but there they are. If anyone feels able
to explain it all, feel free to followup with
something on the details of SCSI termination.
On the connector pinout which I posted, there
separate pins for Logic Return, Motor Return,
and ground. And I pointed out that you should
keep the logic and motor lines seperate.
I just looked at two different versions of
our adapter boards, and both connect all
returns to common ground, and connect both
motor and logic to a common +5V. Personally,
I would be concerned with the motor draw
pulling the logic +5 down too low, or
dirtying it up. Perhaps that
is not quite such a big worry after all.
However, I should point out that we generally
use these with very capable (big) power
supplies. Linear, not switching. So as
you put these setups together, if you
have problems with drive logic blips, think
about that ripple & noise spec.
The power specs should be similar for non-Quantum
drives.
As for extra connectors (16 pin) on Conner drives:
Quantum GoDrives are what we call self-scan, which
means the 8 hour digital scan (the last step in the
testing process which we inflict on every drive, before
we ship) is run not by an externally connected test
computer, but by the microcontroller on the drive
itself. We connect the drive to a computer, and load
all the test software onto the disk. Then we put the
drive in an oven, with only power connected, and it
tests itself. Then we connect it to another computer
and read the test results back off the disk.
Pins 1-4 of J2 (the other end of the 2 x 25
ribbon connector) are reserved (on Quantum drives)
for signals involved in this test process.
Conner drives are self-scan, too. Perhaps they have
the extra connector for this same sort
of purpose. Just a guess. But whatever it is, you
shouldn't need it to use the drive. I think....