Path: blue.weeg.uiowa.edu!news.uiowa.edu!hobbes.physics.uiowa.edu!math.ohio-state.edu!howland.reston.ans.net!gatech!bloom-beacon.mit.edu!senator-bedfellow.mit.edu!pbauer 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> NNTP-Posting-Host: alfredo.mit.edu 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. IÕve never seen inside a Powerbook (IÕm 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....