SCSI DB25 External to 50-Pin Internal

[Xamiche]

Okay, I've create a new project for myself. Towering an Amiga 500. Why? Just for fun. I have a cool little PD device called a SCRAM 500. It has RAM on board as well as an external DB25 SCSI connector. My question is, not being very familiar with SCSI devices, can I create an adaptor to go from a DB25 to a 50pin SCSI device?



Would such an adaptor need any interface circuitry, or would it just be a matter of aligning the correct pins?

I know I could use an external case to house the HD and then just use a DB25 SCSI cable but I'd like to be able to have the HD inside the tower I put the Amiga into. Also, can I have more than one SCSI device on such an interface. Say a HD and a CD-ROM drive?

[Xamiche]

Thanks for the link. :-)

It's not quite what I'm after though. I need a DB25 Male -> 50 Pin IDC Male adaptor. The adaptor in the auction is DB25 Female -> 50 Pin IDC Male. It's cool though. The item in the auction tells me one thing, any such adaptor can be made as a straight up connector converter without the need to include an interface circuit.

Maybe that item and a gender changer could work out. :idea:

[Xamiche]

50-pin IDC? Is this an internal drive?

Yeah, it's the connector on an internal SCSI HD I have. I also have a CD-ROM drive with the same 50-pin connector.

It's good to know it's just a pinning thing. Should be much easier to set it all up.

[Xamiche]

1. I'm going to power the whole thing with a ATX PSU. I have a modified ATX PSU I'm using to power my Amiga CD32s at the moment. I'll just rig up another one for the A500 tower project. The SCSI HD and CD-ROM drive have the usual molex power connectors so there's no drama there.

2. Yeah. Though I'm not sure if I need to terminate if all the connectors on the ribbon are being used by a device. If I use a SCSI cable with 3 connectors; one going to the SCRAM 500, one to a HD and the last one to a CD-ROM, would that be a complete and correctly terminated set up?

[Xamiche]

Ilwrath wrote:

Yeah. Though I'm not sure if I need to terminate if all the connectors on the ribbon are being used by a device. If I use a SCSI cable with 3 connectors; one going to the SCRAM 500, one to a HD and the last one to a CD-ROM, would that be a complete and correctly terminated set up?

The thing you have to remember is that in ALL CASES on the SCSI bus, both ends of the chain MUST be terminated.  

If there is only one connector on the SCRAM, it should have an on-board termination on it's end, so that will take care of one end.  

The other could be taken care of by setting a termination jumper on the SCSI CD-ROM drive unit.

The logical SCSI chain would thus look like:
------------

This would be a correct configuration as it would have termination on both ends of the chain.

Excellent. Thanks for that info. :-)

[Xamiche]

Thanks for the excellent advice from all of the above. :-)

I think I'm going to go the route JimS advised. I enjoy building stuff and I wont have to wait weeks for an adaptor to arrive. Although Radio Shack, or Tandy as it's called here, stop selling such things a decade ago. They're pretty much and electrical appliance store now. Electronics stores are scarce these day. Electronics is not as popular a hobby as it once was. :-(