HDD + SCSI2SD in Macintosh SE?

[PotatoFi]

A friend of mine gave me (!!) a SCSI2SD 5.0B, which attaches neatly to the expansion slot connector with a part that I 3D printed. The internal 20 MB hard drive on my SE still works fine, and while I love the speed of the SCSI2SD, I do miss the noise of the hard disk.

Is it possible to connect both the internal hard disk and the SCSI2SD adapter with a different SCSI cable and a Y Molex cable? What exactly do I need to buy? I’d probably use the hard disk as a secondary, keeping the OS and applications on the SCSI2SD. Eventually, I expect the hard disk to die.

 

[Crutch]

While I haven’t tried this, yes it is definitely possible. 

You’ll just need a three-device SCSI cable (google “three connector SCSI ribbon” or similar). One end goes to your motherboard, the middle connector goes to your Scsi2sd, and the other end goes to your internal HD (or vice versa).  You will need to terminate whichever drive is last on the chain. With a Scsi2sd 5.1 you could do this in software, but I don’t believe the 5.0 allows that, so I’d recommend getting an internal pass-through SCSI ribbon terminator and putting it on the last device. (Or you could probably get a four-device cable and just plug a regular 50-pin terminator in last.) I THINK you won’t need to terminate the other end (at your external SCSI port) because unless you plug in an external SCSI device, this will now leave your motherboard SCSI controller at the other end of the chains and the controller self-terminating, but someone might correct me. Of course if you then add an external SCSI device you will need to terminate the end of the external chain as usual. 

The Scsi2sd shouldn’t need molex power on an SE so you don’t need a molex Y connector. It will take adequate power from the SCSI bus. 

Good luck!

 

[PotatoFi]

Great, thank you! Looks like I can have one here before the weekend for about $9. I *am* using an external SCSI device, a Farallon Ethermac SCSI Link, which has termination built in. My understanding of SCSI is pretty weak (I feel like I'm learning how to use a computer all over again), so I'm envisioning a bus that looks something like this:

Ethernet Adapter - Macintosh SE - SCSI2SD (terminators removed) - Quantum Hard Drive (which I would guess includes it's own termination). 

Am I on track at all there? Or in the original configuration of Macintosh SE and internal hard drive, was termination not needed since it was a 2-position ribbon cable?

 

[Crutch]

Right, I expect you will need to terminate that Quantum either with an internal pass-through terminator or by using a ribbon with a spot for a terminator at the end. My old Quantum drives, at least, are not terminated. (I am also no SCSI expert but have gotten a setup like that to work!)

 

[jupo]

If the Quantum has resistor packs near the 50-pin connector, then it's terminated. Most stock drives should be, since they're installed as the only drive on the bus.

 

[PotatoFi]

Welp, I haven't had much luck with this. Here's my current setup with a 3-position ribbon cable:

Macintosh SE > Miniscribe M8425S HDD (resistor packs removed, jumpered SCSI 1) > SCSI2SD (resistor packs in place, configured SCSI 0)

I'm not totally sure that I have the HDD jumper settings right. One of my friends found the manual but the orientation and settings on the jumper pins are kinda vague. Tempted to give up on this as I've tried pretty much every combo I can think of.

 

[Crutch]

Have you tried popping an external terminator onto the SE’s SCSI port?

 

[PotatoFi]

Have you tried popping an external terminator onto the SE’s SCSI port?

I don't have an external terminator, but I do have a Farrallon SCSI/Link with built-in termination (verified working). Plugging that in had no effect.

I'm pretty much ready to give up. I don't understand why it isn't working, and I don't know how to proceed.