Mac Plus won't recognize!

[Yoshihide]

I'm trying to connect a SCSI HD to the Mac Plus, but for some reason, it's not recognizing it.

Actually, it's not even recognizing that the drive is connected.

Not even an old version of Silverlining will allow me to choose the disk and format it properly.

Is there some kind of trick to make a SCSI HD work with the Mac Plus?

I have 2 Mac Pluses, and both won't recognize all 4 SCSI drives.

I'll need an external HD (or an external Floppy Drive, which I don't have) to install System 6 from the installation disk. It's nearly impossible to install with only one floppy drive (endless disk swapping!)

Thanks

 

[porter]

Boot from a floppy and run SCSI probe to have a look at the bus and see if it's advertising itself.

You have two problems...

1. As I understand it the Mac Plus requires drives that default to using a 512 byte sector ( or some similar initialisation ), later Macs did a negotiation with the drive to set this up. I use an old 40Mb drive for this very reason.

2. The original SCSI hard disk setup program only recognizes Apple supplied drives, unless you either using the A/UX version or patch it.

 

[equill]

The SCSI port of the Plus needed an HDD formatted for 1:3 interleave, ie a drive slowed down in data acquisition rate. Silverlining 5.8.x gives more control over such matters as block size, that interleave requirement and other matters, while still adhering to Apple's partition scheme (5, of which only one partition is the visible 'mounted' volume). Its GUI is rudimentary compared with those of Silverlining vv. 6.x.x, but a little playing will get you there as well as give you useful diagnostic information about the drive. Apple's utility (HD SC Setup) is barebones, laconic and useful only if there is no problem, such as needing to format a drive that does not include an Apple-blessed ROM.

de

 

[Yoshihide]

I tried using Silverlining version 5.5, and when I try to "Select Drive..." from the File menu, I get...

"SCSI bus is not responding. Check that devices are connected and powered up."

Yes, an old IBM 80MB drive (with Apple ROMS) is properly connected with SCSI ID 0.

I'm stuck.

Could the SCSI bus be blown out on both Mac Pluses? Are they THAT easy to destroy?

 

[porter]

"SCSI bus is not responding. Check that devices are connected and powered up."

Have you gone through the termination options?

What does SCSI-probe say?

 

[tomlee59]

Porter's question is a particularly relevant one. The Mac Plus does not supply termination power. Termination resistors perform two functions -- they reduce transmission-line reflections from bending the bits, and they also provide a DC return path to assure proper logic levels. The DC, in turn, has to be supplied by something external to the Plus.

Drives generally have a variety of jumper-controlled options for how termination power is to be supplied (e.g., from the host computer, from a local power supply, etc.). If it is currently set to receive term. power from the host, then the system will behave much as you have described.

 

[Yoshihide]

What does SCSI-probe say?

Tried SCSI probe, but it looks as if the drive isn't connected at all.

Drives generally have a variety of jumper-controlled options for how termination power is to be supplied (e.g., from the host computer, from a local power supply, etc.). If it is currently set to receive term. power from the host, then the system will behave much as you have described.

Yes, I was going to ask that too. I have a "SCSI System Cable" manual, and it says that if there is no internal drive, a terminator must be connected between the Mac and the drive (unlike the usual way: the end of the chain, or the 2nd connector of the drive).

I don't know if that has anything to do with this, but how do I get termination power from the drive itself? One of my newer SCSI drives (9GB) has such an option, but not on the IBM 80MB drive.

 

[equill]

... how do I get termination power from the drive itself? One of my newer SCSI drives (9GB) has such an option, but not on the IBM 80MB drive.

The HBC (the Plus) must supply termination power to its own on-board termination (resistor packs). Older Macs were not designed also to supply termination power to an external daisy-chain. The termination arrangements at the other end of the daisy-chain have to be taken care of by the user, ie the enclosure supplies 5V for the HDD's logic and 12V to drive the platters, but unless there are resistor packs on the HDD's logic board and a means of supplying them with 5V, the drive is suited only to a non-terminal position in the daisy-chain, or the enclosure has to provide for termination by way of a CN-50F socket into which a CN-50M terminator can be plugged. This latter case allows for other devices to be daisy-chained, of course.

Later drives provided optional termination and termination power, usually shown on a header as TE (enable) and TP (power) in, say, Seagate's lexicon, and less intuitively in Quantum's case.

de

 

[Mac128]

... how do I get termination power from the drive itself? One of my newer SCSI drives (9GB) has such an option, but not on the IBM 80MB drive.

the enclosure has to provide for termination by way of a CN-50F socket into which a CN-50M terminator can be plugged.

I believe this is the answer for your drive if there is no apparent external switch. An external terminator. You might try opening the enclosure to see if there is a resistor you can move to terminate the drive. If this is an Apple OEM, then according to their drive manuals these drives could self-terminate for use with Macs like the Plus. You are probably better off getting yourself a couple of external terminators though, lest you have the same problem when you try to use the drive with a later Mac down the road and forget what you've done.

 

[Yoshihide]

Thanks everyone! I finally got it to work!

Seems like the problem was with the termination.

The drive inside the case is an IBM WDS-L80 (probably) with Apple ROMs. Since it came in the LC II without any jumpers installed, I thought it was terminated by default.

Maybe, it wasn't so.

Installing a standard 50pin external terminator on the 2nd SCSI port of the drive enclosure made it work.

So it's double-terminated now? Is this OK?

 

[JRL]

So it's double-terminated now? Is this OK?

Yeah, that's perfectly fine.