Physically Change internal "A" drive to an external "B" drive

[djglish]

I'm trying to build an external case to hold a CDR drive, hard drive, Syquest drive and external floppy for an Atari ST system.   I have a drive pulled from a dead ST that I would like to use as the external drive.  

I'm assuming I'm going to have to change some of the jumpers to make it work as a "B" drive.  The drive is marked with D357 and a serial number.  It is the classic Atari drive with the large slanted ejection slot.  

There is a jumper on the bottom right behind where the floppy cable plugs in.  The jumper is between what appears to be the 0 pin and the second pin (there are three pins total).  There is also a three  pin spot that does not have any jumper on it.  There is a "G" near one pin (ground?)

 

If I get this done I just need to figure out how bring the cable out to the ST.  

The other items will be on a SCSI chain going to an ICD Adscisi+

[Almerian]

If you are going to use the external round floppy connector, you might not have to change anything on the drive itself.

I seem to remember that an external drive connected to the floppy port was automatically a "B" drive on ATARI ST models with an internal drive. That's because only the "B" drive select is made available on the external floppy connector of those models, connected to the "drive 0 select pin" of the round floppy connector.
The only exception would be the original ST, ST+, and STM computers as they did not have an internal drive.

 

In short, no need to change the drive number then, just connect the drive to the "drive 0 select" on the round floppy connector.

[TGB1718]

Depending on you ST model, you can change the Drive select by using link on board, see the attached diagram,

the one on the left is for an STE, the other a 1040ST

 

 

[ijor]

If I understand correctly, you want to take the internal drive from one computer and use it as the external one on another, right?

 

If so there is no need to change any jumpers or straps, you "just" connect it to the external connector. The external connector is already wired for the correct drive selection.

 

If you want to use the internal cable instead of the external connector, say, using some kind of splitter, then it depends on the exact computer model. The main difference is that the STE cable carries both select signals, but the ST one does not, at least not by default.

[djglish]

I do want to take an internal drive from one computer and use it as an external drive for another computer.  Good to hear that it should be an easy thing to do.  

 

Now to figure out how to bring the cable out of the case.  Not sure how long of an external drive cable I have.  I also have to figure out how to mount the Adscisi+.  I think I have a long enough SCSI cable in my box to run to the other 3 devices.  I'm using an old smaller Mini ATX style case.  I'm going to put an on/off switch on the back instead of using the front switch.  

[ijor]

23 hours ago, djglish said:

I do want to take an internal drive from one computer and use it as an external drive for another computer.  Good to hear that it should be an easy thing to do. Now to figure out how to bring the cable out of the case. 

 

Again, the "easy" way, at least electronically, to do that is not to bring the cable outside, but to use the external connector. If you want to use the internal cable, which might be easier mechanically, then unless it's an STE, it requires some modification to the motherboard because the drive B select signal is not present in the internal cable.