Dead HD20

[trag]

Just wanted to weigh in since I didn't see this mentioned. It has always been my understanding that the Rodime drive was indeed fitted with a proprietary controller. This Apple Tech article indicates one conversion method I've heard of which seems to support that the drive itself could not be converted to SCSI, but the interface logicboard could be replaced to interpret for SCSI (or maybe I'm reading too much into it).

What I find particularly interesting about this article, is that it implies that, at one time, someone at PCPC understood the interface to the HD20 drive--either that or this adapter sits between the floppy connector and the host computer, but I do not think that is the case. I think it is a replacement interface board, from the way the article is worded.

So, we must now find someone who did design work for PCPC...

 

[macdownunder]

I think it is a replacement interface board, from the way the article is worded.

I saw (but did not bid on) one of these interface kits on eBay not long ago. The listing appears to have dropped off the completed search.

From what I recall, it appeared to replace the logic board in a HD20 to provide a SCSI interface to the HD20 drive mechanism.

Regards,

Macdownunder

 

[equill]

While it is perfectly conceivable that Rodime might have used different platter separations and different head constructions in the same motor-and-platter diecast box as they later used for SCSI drives, providing a different logic board also for each style of storage, it seems a little painful. JDW's pics of the Rodime in his HD20, and my SCSI drive, differ only in 'Option Number' (read construction/storage mode?) and Build Level (que?), nonetheless.

I have to presume that Rodime never 'filed' its secrets on the Web?

de

 

[Mac128]

That's how I read the Apple article, too. While I am the last person to discuss technical matters of this nature, if equill's drive is physically identical to the HD20 drive mechanism, I would suggest that the circuit board interface on the drive is the difference and is designed to interface with Apple's HD20 digital board which is sending very different signals than a SCSI interface. I suspect any conversion kit not only provided access to the Mac's's SCSI bus but also translated those signals to the proprietary hard drive controller. So theoretically you could just trade disk controllers for a native SCSI and be all set to plug into a SCSI interface. However, that doesn't really get you any closer to converting the HD20 to SCSI without a SCSI logic board. In other words, strip the guts out of the HD20 reusing only the hard disk and power supply but replacing all logic circuitry. In which case why even keep the drive itself? And the power supply would have to be adjusted to the needs of the new mechanism.

 

[JDW]

I have found this thread to be quite interesting, especially the technical points hinting at the HD20's interface and protocol. But for myself, I am even more interested in figuring out how to put a bootable flash drive inside my old non-SCSI Mac 512k! Or perhaps substituting a 20MB or 32MB CF flash card for the Rodime drive mechanism in the HD20! Or perhaps swapping the MMi drive mechanism used in the HyperDrive kit with a 20MB CF card! Or for those without either the HD20 or the Hyperdrive, having a CF card and controller kit to be used internally in the Mac 512k and higher (and 128k too, if it has the RAM for it).

Flash drive options exist for the ancient Apple II series, as I am sure most of you have seen on EBAY from time to time. So why not the Mac? Makes no sense to me as we Mac collectors should also have an equally interesting number of modern add-ons for our old machines! But then, perhaps this is a topic for another thread.

 

[Mac128]

While it would be a dream, as Dan Knight points out, someone would would need to write drivers for it and I'm afraid anything less than a System 6 would not get much attention.

http://lowendmac.com/musings/mm07/0815.html

However, I have routinely used IDE to SCSI converters so I could use smaller IDE, cheaper drives on an old SCSI internal bus. Since there are ATA/IDE Flash drive interfaces, this may well be a solution with the right connectors. No special drivers, just connect your flash drive through the IDE to SCSI adapter and plug into your SCSI bus. Depending on the flash drive you may need a special application to format it before you can see it on a very old System (like a ZIP 100 drive), but once formatted it might work on any old System just like my ZIP does.

I'm thinking the better approach at this point would be the MacMinitosh running Mini vMac and expand its capabilities ... which I know Paul Pratt is doing. This way you can have the best of both worlds in one case (I think I would mount my MacMini upside down and access the DVD slot through the bottom side vents to modify the case as little as possible.

But, you're right this belongs in it's own topic ...

 

[Mac128]

Interesting solution.

Can't figure out if he's talking about an HD20, an HD20 SC or a third party drive. Either way, the Rodime mechanism looks awfully familiar!

http://www.bernardbelanger.com/computing/hd/index.html

 

[JDW]

Mac128 (love your new Avatar BTW),

You Google-up the most interesting classic Mac links on the web! That drive indeed looks to be the same as the drive mechanism inside my HD20. I just never opened the housing to see the heads move.

Thanks for bring this to our attention.

 

[Charlieman]

Quote from the page: "This one is an old one, a 20 MB Rodime that came with a Mac Plus." Presumably the drive came in a third party external SCSI enclosure (Rodime drivers were very common in Europe and I've got loads).

 

[Mac128]

Anybody on the forum with an HD20 got the original manual or a copy of one?

 

[equill]

The Service Source for the Hard Disk 20 was, before Apple's counsel assiduously shut them down, available from a number of sites. If you find one that they have missed, don't post its URL.

As far as I am aware, the hard-copy manual 030-1228-A has not been downloadable from Apple at all.

de

 

[JDW]

If you find one that they have missed, don't post its URL.

But be sure to PM me! :b&w:

 

[Charlieman]

Anybody on the forum with an HD20 got the original manual or a copy of one?

I've just dug out my copy. The media kit comprises the HD20 Manual (030-1228-A), an addendum (032-0026) and startup disk (690-5067-A). Those documents don't cover anything that I haven't written up already at http://www.vintagemacworld.com/hd20.html

There is some additional information in the service procedures -- I have a paper copy from 1989 that includes a diagnostics section for the HD20 dated November 1986:

-- Only use a Plus or earlier to try to fix an HD20. Don't use an SE or II.

-- Boot from the HD20 Startup Diskette and hold down the Command and Option keys through the entire boot process to rebuild the desktop.

-- Boot from the HD20 Startup Diskette and hold down the Command, Option and tab keys through the entire boot process to initialise the HD20.

I haven't tried the third procedure and would be interested to hear if it is different from the optional procedures available in "HD 20 Test".

For info, the paper doc is "Apple Service Technical Procedures, Macintosh Family, Volume Two" (072-0228). The doc covers peripherals, monitors and cards for early Macs upto and including Mac II. Volume One (same part number) covers the Mac 128 through to IIcx system boxes.

 

[Mac128]

LOL, yes Phil, you indeed comprise all the current comprehensive information to be found on the net! I might have known you had the original manuals. Would love to get my hands on a PDF of the manual though ... mainly to read how Apple explained the HFS format and instructed the new adopters to implement it. As you well know, Apple quietly introduced it with the HD20 in September 85 when no one would have known anything about HFS and would have resulted in a lot of confusion unless it was clearly explained. Though as you say, the manuals don't cover anything you haven't written up. The disk part number looks as though it may be the original 2.1/5.0 v1.0 as well. Thanks for digging around to assist with this!

 

[Charlieman]

Would love to get my hands on a PDF of the manual though ...

I don't have the time to do the scanning to create a PDF. Drop me a line privately, David, and I'll investigate whether I can produce high quality photocopies to post to you. I'm not sure about hosting -- I'll have a chat to some of the people who have reproduced Apple II stuff to see if Apple generate any legal problems.

 

[JDW]

I don't have the time to do the scanning...

If someone who has these wants to ship them to me (in Japan), I will MAKE THE TIME to scan them for everyone to have access to. (And there's no reason bitmap scans really need to be in PDF format. Since there's no vector text in such scans, even JPEG format will do.)

 

[Mac128]

FYI, I have the HyperCard stack of the HD20 service source manual and trust me when I say it doesn't offer any revelations other than preventing you from breaking the clips when you open the case. It's from a time when Apple's answer even to their field techs was "return to Apple for repair". Anybody who wants a copy just PM me.

I too have finally been able to diagnose my dead HD20 and it appears to be a dead drive. The logic board powers a replacement drive just fine. This is most likely the case with yours Academician since mine exhibited all the same symptoms as yours.

I did open the HD itself and the platters and the internals all seem to be in working order. So if nothing physically is damaged, then does the problem lie on the drive's circuit-board? I haven't a clue as to where to start looking, if so.

It is sad to think that as these drives fail there is no good way to replace them. In fact I find it almost unbelievable there is no modern way to replace the drives, even with some sort of homemade adapter. Well, here's hoping.

I was looking at the Apple Service Source manual for the HD20 and they list the drive as part number 661-0373. This happens to also be the same part number as the Apple 20SC hard drive that shipped with the HD 20SC, the original SE 20MB configurations and may also be in the II, IIx, IIcx, IIci & IIfx, SE/30 & possibly Classic. So I checked the service source manuals for them and sure enough, Apple calls them "Revision A". Revision B is a different part number and cannot be interchanged with the Revision A drive. Unless Apple decided to reuse a part number, the drive in the HD20 appears to be a SCSI hard drive of a certain configuration. In which case, it should be possible to adapt any SCSI drive to work with the HD20. Anyone with a 20MB drive from one of those Macs should check the part number and see if it may be a compatible drive with the HD20, since you can switch out your SCSI HD with any old SCSI drive, but the HD20 can evidently only use one.

FYI, Service Source indicates of the two Revisions of the 20MB hard drive the 661-0373 is the only one that is drop-in replacement. In other words all other drives require the techs to insert/remove them from their carrier/sleds and configure the dip switches, terminator resistors, etc. for the specific enclosure, but the 661-0373 is pre-configured by Apple

 

[Temetka]

If it were me, I'd strip a crappy external scsi and stick in that case.

Or try and stick and LC mobo or something else neat inside. I would spend all of 40 seconds trying to save a 20MB HD that is just as fast as a floppy. Unless of course a client was paying me large piles of cash (say a couple hundred bucks) to save. Then I would use every trick in the book and even come up with some new ones.

 

[Maccess]

Hahaha. It sounds like something I would do. I have a Rodime too (only the case remains), and a GCC HD20 Hyperdrive. Nice cases.

Some later cases, notably the Micronet ones and Mass Micro ones now have IDE drives with either USB or SCSI bridges depending on their use.

 

[Mac128]

If it were me, I'd strip a crappy external scsi and stick in that case ... I would spend all of 40 seconds trying to save a 20MB HD that is just as fast as a floppy.

The whole reason we are trying to save these drives is because they are the only ones that will work with a stock 512K/e which are still around. It also has to do with something many of us on these forums are committed to, preserving these artifacts in their original condition.

Besides, I had already suggested using my Zip 100 drive in the case, assuming the drive were completely beyond repair. The one problem with that idea is neither the 512K or 512Ke are SCSI capable. The only way to add that functionality is modify the logic board and case, which sort of defeats the point of restoring these Macs to their original condition and preserving them.

I know JDW made himself clear on the oddball 128K mourning thread about the "stock" differences between his SE and 512K, but unlike the SE, despite the fact Apple did not build into the Macintosh any expansion capabilities, many third parties provided some excellent products to add these capabilities. Though Apple did not support them directly, the fact that references to many can be found in Apple's Knowledgebase is sort of a tacit approval on their part. With that in mind, like others on the forum, I think anything that can be added to a vintage Mac that is non-destructive preserves it in its original condition as it might have existed at the time. In the case of the Dove MacSnap SCSI upgrade, it actually takes advantage of the one feature of the Mac that Apple did design to be upgraded: the ROMs. The only socketed chip on the logic board. That my friends is the original Macintosh expansion slot! Pull the ROMs, insert the board and re-install the ROMs. Instant SCSI, the port for which cleverly takes the place of the battery cover on the rear. It does require 128K ROM upgrade, but again, the Macintosh was designed for that. Depending on when you bought your 512K, it may well have been an option you had installed upon purchase like you might extra RAM or bigger hard drive today.

There were other solutions which clipped onto the CPU and RAM which were also non-destructive solutions. Though as Larry Pina points out, any additional power consumption to the already overtaxed Mac must be compensated for or risk major component failure AND that really defeats the goal of preserving these old Macs!