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Way to force master?

Posted on 2003-11-02
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Last Modified: 2008-02-26
I have a TEAC DV-28E DVD-ROM module that I'm trying to adapt to work with my laptop. The connector matches up perfectly (I swapped out the interface converter card out for one from another TEAC CD drive that has the same internal connector) with the connector in my laptop, and powers-up just fine. I had looked up the specification outlines for both the original TEAC drive I'm replacing, and the current one, and the connectors have the same pin-outs, so it should be compatible. It even FITS in the same space as the original module.

There's just ONE PROBLEM! The drive wants to be a SLAVE when it should be a MASTER. Apparently, the laptops that the drive is manufactured for have both the expansion bay and the hard disk on the same ATAPI/IDE bus. In my case, however, the expansion bay and the internal hard disk are on separate IDE channels. Thus, the BIOS expects the CD-ROM drive or ANY expansion bay module to be device 0, the MASTER. The drive does not have any jumpers to set which it is, the firmware must have it hard coded.

Because the drive is indentified as SLAVE and there is no master to control it, the drive cannot be used at the moment.

Now, I know that the IDE interface has many pins that control communicaton between SLAVE and MASTER and also tell the host which is which, and I was wondering if I might be able to force the drive into being MASTER by simply blocking a signal? Is there a way?

There does not seem to be any firmware update out there for the drive, or else I would try my hand at simply modifying the firmware image, but the only copy of the firmware seems to be on the drive itself (it IS flashable).

Any thoughts on how to for the drive to be MASTER?
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Question by:GuyPaddock
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Author Comment

by:GuyPaddock
ID: 9668788
I have heard it suggested that a simple modification can be performed to the similar TEAC CD-224E on some models where they also want to be SLAVE. Could it be what I suggested, blocking a signal?
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Accepted Solution

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chicagoan earned 250 total points
ID: 9669118
You can get the integrator's resource manual with the pinouts from DSPDTSG@TEAC.COM

On the Slimline drives, setting is made via the firmware. With standard drives, the setting of the last two digits will tell you how the drive has been set at the factory. – 83 stands for cable select (CS) and – 93 stands for inverted cable select (CS-). However, this does not apply in many cases on notebooks, as the OEM often exchanges these for hardware design reasons. TEAC will reflash the drive (not free I believe)

PIN47 and PIN48 of the I/O connectors control cable select on these I believe
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Author Comment

by:GuyPaddock
ID: 9675562
Well, I did some digging in the apple developer guide (I'm trying to make this drive work with the expansion bay on a Powerbook 1400... but don't get hung up on that) and found that CSEL (Cable Select) is an unused connector; they recommend that hardware developers wire it directly to the ground wire to force a master connection, as a master-slave situation should never arise (hence, my problem, as the controller isn't expecting it). Now, the drive I have ends in "-93" in one of the model #s, indicating inverted cable select. TEAC has also told me that it is set to cable select, just not which one.

I am assuming that the interface card I got off the original CD drive has the CSEL pin wired to the ground. If the drive IS cable select, but INVERTED cable select, then I am assuming I need to BREAK the ground connection to the CSEL pin in order to force the drive to be master? If this is so, then can't I simply cut the trace for that pin on the EBM interface card?
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Expert Comment

by:chicagoan
ID: 9676008
Pins 47 and 48 would be shorted, you want to isolate pin 47.
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Author Comment

by:GuyPaddock
ID: 9691524
Through trial and error, and by using the information both you and TEAC provided to me, I discovered that the drive I have is, in fact, set for normal cable select. The problem was that the original drive set its position via two tiny switches, thus the drive did not require cable select. I tested the cable select pin (pin 47) on the connector to the drive (i.e. the connector that connects to the drive, on the opposite side of the connector that connects to the expansion bay) and found it not to be connected to anything. This meant that cable select was already isolated!

Conveniently, two ground pins (45 and 43) are right next to pin 47, so I soldered pin 47 and pin 45 together, where the leads are surface-mounted on the board.

As soon as I inserted the drive, the disc inside was mounted without a problem. However, there are still two small issues that I am hoping to address. The first is that I cannot boot the Powerbook using the drive; if the drive is in the expansion bay during the startup test )before and during the appearance of the happy mac), the Powerbook will FAIL the startup test. The error codes are 00000000F and 000000001. It doesn't matter if a CD is loaded or not, the test fails. Second, if the powerbook attempts to go to sleep, and there is a CD loaded in the drive, the Powerbook will either:
1) Lock-up after dimming the screen
2) Go to sleep, then request that the expansion bay module be reinserted on wake-up, followed by a lock-up if I remove and reinsert the module
3) Crash the Finder and lock-up if I attempt the sleep command again

I'm thinking that the drive isn't receiving the power commands properly, or is interpreting the ones it receives differently than intended. The drive will act as if I just inserted a new CD right before it goes to sleep, if there is a CD loaded.

Any thoughts?
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Expert Comment

by:chicagoan
ID: 9691906
...some sort of machiavellian way of getting you to buy Apple branded hardware?
This is a question for the MAC hardware area... I haven't had my hands on one since they had 40 column dispays...
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Author Comment

by:GuyPaddock
ID: 9697108
Ok, thank you for helping me get the drive up and running. You get the points.
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Expert Comment

by:chicagoan
ID: 9697920
Thanks, sorry about the lack of MAC expertise, I'm still pondering the mysteries of SBUS
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