Highest Version of System Software on Mac 512K & 512Ke

In order to boot at all, the HD20 INIT has to load into RAM at the appropriate moment during startup. If System 6 does not have any provision for this ROM patch, then I don't see how it could work and without it a 64K ROM Mac simply can't boot System 6 if it requires HFS to boot. Obviously System 6 can read and write MFS, but could the System really need HFS formatting to load the boot code?

I just did an interesting formatting on my Mac Plus by installing a minimum System 6.0.5 for Mac Plus onto a 400K HFS disk. Then I dragged the 400K HFS disk onto a freshly formatted 400K MFS disk. THe result was slightly different than I expected, it copied only the files onto the MFS disk and did not reformat to HFS. I then further dragged the system contents out of the folder so they clearly resided on the root directory (even though technically they were already there). It's interesting that the Mac knew to convert a real folder/directory into a fake folder grouping. Next I copied the HD20 INIT v.1.1 file onto the 400K MFS disk.

The 400K MFS disk will boot the Mac Plus, so to the extent System 6 needs HFS to boot, it's not in the formatting of the disk. Now to the 512K – no dice. It does pretty much what JDW reported: Happy Mac, to Welcome screen, but just about where I would normally see the HD20 loaded message, the screen freezes and the box begins to cycle. When I boot up with a regular pre-system 6 MFS HD20 boot disk and try to switch to the System 6 MFS disk, by launching an application from it, the application loads fine. Upon quitting, I too get an Error 2. The Application SystemVersion reports 6.0.5, but upon exiting reports error 2 as well. When I used an MFS 400K disk without the HD20 INIT, the exact same startup sequence occurred. That indicates to me that the HD20 is not a factor. In fact, as I suspect, the HD20 patch code is likely not even present in System 6, so despite the fact it is included on the disk, the System doesn't even know what to do with it – that, or it is hanging up at some point before it attempts to load the HD20 INIT. But what loads before the disk driver and HFS code? I suppose it is possible that System 6 attempts to load something from a 128K (and up) ROM before accessing any ROM patches for an unsupported 64K ROM.

Another interesting feature of this System 6.0.5 System ... the minimal system installed for the Mac Plus by default contains AppleTalk. It is possible that System 6 AppleTalk is somehow incompatible with the 64K ROMs, or loading before the HFS ROM patch can be loaded into RAM?

Either way, any effort to get System 6 to run on a 512K Mac would require a system hack which defeats the practicality of running System 6. Unlike the "Magic Disk" solution for formatting 800K MFS disks on a 512K Mac, getting System 6 to run does not seem to be a simple matter of installing the correct sequence of files. Both JDW's tests and mine suggest a much more serious hack is in order to get the System booting, or even running after booting off another disk and switching over to it. If one were limited to a stock 512K, it would seem that one could boot over to System 6 on an application by application basis in order to use a program that only runs on System 6. However, if upon exiting such applications the system must be restarted, it is not a very practical remedy.

I think Mac512.com MUST have been using a 512Ke and not realized it. The HD20 file makes no difference to a 512Ke and it seems to run System 6.0.8 without issue. Given that Apple does not recommend System 6 for a 512Ke, it is unlikely an installer would produce a custom install for anything below a Mac Plus. Therefore, if a standard install of Mac Plus software onto a 400K disk will not yield a bootable or even switchable System 6 disk, then there's not really much point. That said, I am certainly curious as to what is causing the actual limitations and will probably keep looking for a "hack" that demonstrates the removal of those limitations, but that is what it will be, not an easy workaround of standard software.

--

In looking at these Apple docs, it would appear that despite the fact the SE/30 does not have a driver in its ROM, the HD20 INIT does not allow access. Apple further refers to a special INIT which allows the HD20 to be mounted by the SE/30 and files copied from, but not written to. http://docs.info.apple.com/article.html?artnum=6182

Since the SE/30 ONLY runs System 6, it would seem that System 6 is not able to implement the HD20 INIT ROM patch. If it could, then the fact the SE/30 does not have the driver in ROM should not be a factor in its ability to access it. As the driver is in the Portable/100's and Classic's ROM, System 6's limitations are irrelevant. Interestingly Apple created an NEW INIT for the SE/30, but ONLY to access the HD20, not utilize it, their recommendation is to copy the info to a new SCSI drive (yeah I'll bet!) ... but seriously, what would be the real technical limitation to running an HD20 on an SE/30? The IIcx & IIsi seems to suffer from the exact same problem as the SE/30, yet it is not mentioned on Apple's site. Nevertheless, the IIci does have the HD20 driver in ROM and is otherwise identical to the SE/30 & IIcx/si. So the SE/30 INIT should work on the IIcx & IIsi as well and if the Classic II doesn't have the driver in it's ROM as well, then it would likely work on it too. But would it work on the 512K?

MORE IMPORTANTLY, Where is this INIT today? Is it included on an SE/30 disk set? I have looked all over the internet and found no other references to it.

Apple further refers to a special INIT which allows the HD20 to be mounted by the SE/30 and files copied from, but not written to. http://docs.info.apple.com/article.html?artnum=6182

Click to expand...

I've been begging for someone to post that for ages. If any of you out there have access to that magical INIT, please PM me! I wish to test and offer the classic Mac community a complete report.

Thanks!

By the way, the minimum OS for the SE/30 is 6.0.5. The maximum compatible OS is System 7.5.5. (And with a IIsi or IIfx ROM and a System File hack, you can run 7.6.1 and 8.1.)

UPDATE: This Apple article makes it clear that 6.0.3 can boot an SE/30.

Here's a curious entry:

Subject: Hard Drive 20Date: Sat, 27 Sep 97 09:51:39 -0800

From: "B.J. Major"

To: Classic Posts

In reply to:

To: Classic Posts

From: brobson

Date: 25 Sep 97 18:24:20 -0500

Subject: MacPlus/mounting a hard disk

I just found an Apple Hard Disk 20 (model M0135) that looks like it connects

to the floppy port of my Mac Plus. I'm not sure how to go about testing

and/or using this drive. Will I need to initialize it? How will I know if

the CPU is recognizing it? I assume I would need some utility for such

things. Any advice would be greatly appreciated.

Brian Robson

I've got one of these and it still works very well. Earlier versions of

System 6.x software contain the "Hard Drive 20" extension/init that you

need for it. It can be initialized/reformatted with the OLD versions of

the Apple HD SC setup utility included with System 6 software. And yes,

the Mac will treat it like a big floppy. You'll know if the CPU is

recognizing it because its icon will (same as Mac hard disk icon) will

show up on the desktop. My Mac Plus boots from this drive.

--bj

Enthusiastic Barbie collector and doll-displayer

Apple //, ///, and Macintosh user/supporter/collector

Click to expand...

And this from the Apple Developer's IIsi guide is just maddening:

Hard disksThe Macintosh IIsi computer’s internal one third-height, 40 or 80 MB

hard drive connects to the 50-pin industry standard SCSI connector

on the Macintosh IIsi main logic board. Support for an HD20 hard

drive is provided through an 'INIT' resource that you can install in

the System Folder

Click to expand...

Finally, the smoking gun. I found a read me text but alas no INIT off a developer CD:

Macintosh II HD-20 Support

6/5/87

Warning:

This software is not supported. Additionally, the hardware and even the manual (this document) is not supported. It is not a product, and is to be used at the risk of the user. Caveat Emptor!

!

Macintosh II HD-20 Support

! Warning:

Since the Macintosh II internal IWM port is not buffered (as external IWM ports are in other Macintosh products); there exists a real danger of causing severe damage to the IWM itself when installing. Taking the precautions recommended here minimizes the risk of this happening, however some damage may still occur since the Macintosh II was not designed to support the HD-20. Please read all of this document before even attempting to install any of the hardware. The greatest danger is in installation and removal. At the very least, please keep the number of times that you install/remove this hardware to a bare minimum

!

Installation:

• Turn both the Macintosh II and the HD-20 off. This step is paramount in avoiding costly repairs to both machines.

• Remove the cover of the Macintosh II.

• Touch the power supply in an effort to remove static electricity from your body.

• Remove the floppy drive cable (if your MacII is so equipped) from the internal IWM port #2 (the connector nearest to the NuBus slots).

• Connect the ribbon cable to the IWM port #2.

• Feed the ribbon cable out the rear of the machine (through an open slot access port).

• Replace the cover on your Macintosh II.

• Remove the screw and top cover of your HD-20.

• Touch the power supply in an effort to remove static electricity from your body.

• Remove the cable coming into the HD-20 at the 20 pin connector (this looks amazingly like the Macintosh II's IWM port connector).

• Connect the ribbon cable to the 20 pin connector inside the HD-20.

• Leave the HD-20 in a position where it will be least likely to cause accidental eloctrocution and where the fan is least likely to get external objects (your fingers) in it.

• Turn on the HD-20. (continued on next page)

• Turn on the Macintosh II.

• After booting the Macintosh II, insert the floppy drive to drive #1 (located at the far right hand side of your Mac II) and copy the file "MacIIHD20" to your system folder.

• Select "Restart" from the Special Menu.

Your Macintosh II will now reboot mounting the HD-20. You are now in a position to copy data from the HD-20.

!Recommendation:

Since this software is RAM-based, it is slower than the normal floppy disk driver. You are also at risk of damaging your computer when you install the hardware affiliated with this software. It is the recommendation of the author that you use this software as it was intended, to retrieve data from your HD-20 and place it on a different storage media. Nothing prevents you from using it in an "extended" fashion, except that you are running a risk and there was not enough time to properly trim the execution loops of the driver. I recommend against it.

!

After copying your data from the HD-20, you should remove it to guard against the possibility of an accidental electrocution, damage to your computer equipment, or both.

Removal:

• Remove the file "MacIIHD20" from your system folder.

! Warning:

This software must be removed from the system folder prior to disconnecting the HD-20. Failure to do so will require booting off an alternate system and removing the file "MacIIHD20" from your original system folder while under the alternate system.

!

• Turn off your Macintosh II and your HD-20.

• Touch the power supply of the HD-20 in an effort to remove static electricity from your body.

• Remove the ribbon cable from the 20 pin connector.

• Replace the original cable for the HD-20, replace the cover and secure it with the screw that you previously removed.

• Remove the cover of your Macintosh II.

• Touch the power supply in an effort to remove static electricity from your body. (continued on next page)

• Remove the ribbon cable from the IWM port #2 connector and remove the ribbon cable from the computer.

• Replace the cable from floppy drive #2 (if so equipped) into the IWM port.

• Replace the cover on your Macintosh II.

This completes the removal process.

Use:

The use of this software or hardware voids all warranties on your HD-20 and Macintosh II. Once it is in place, you may use the HD-20 as you would normally, realizing that not enough time to properly modify the driver has been given. You will experience especially long waiting times should you choose to write to the HD-20.

! Warning:

Do not connect an external floppy drive to the pass through connector of the HD-20. This software does not support such configurations. Additionally, the hardware does not support older single sided drives from the IWM port. Failure to comply will bring unexpected results.

!

You may however connect another HD-20 to the pass through connector of the HD-20. The additional HD-20 will operate as does the first.

Configuration:

You will need to have at least the following equipment. A Macintosh II equipped with a viedo card, monitor, ADB mouse, and a SCSI hard disk. This hard disk must have a system folder on it and be the "boot" system. An HD-20 in operating condition. A ribbon cable (20 conductor) with keyed "L" connectors on each end exactly with the same keying as the floppy cables inside the Macintosh II. Appropriate tools for removing the covers of both the Macintosh II and the HD-20.

Click to expand...

Now that I've had a chance to sleep on this and reflect on what this means ... obviously somebody at Apple realized there was a need to get data off of an HD-20 by consumers who no longer had access to an older Mac or external SCSI drive. In an effort to keep them happy they offered this "temporary" driver (and ensured they didn't keep using that HD-20). However, the fact that it was first made available for the Mac II, may raise more questions than it answers:

Since the Mac II was released with System 4.x, if this INIT was compatible with it, then it has less to do with a System 6 workaround than patching into ROM at a different location than the HD20 INIT, possibly patching drivers only and NOT HFS since the II series did not need HFS. Therefore, this driver will likely NOT work on a 512K assuming System 6 needs HFS awareness to function (and that is why SYstem 6 is not loading on a 512K). Is this the same driver as used in the SE/30? Probably. Since the SE/30 was based on the IIx, it would make sense. Clearly as long as the System software knows about and where to patch the INIT into ROM, then it will. This brings up a question about just how these INITs worked. Since the HD20 will not work with System 2.0, but will work with System 2.1, I assumed that System 2.1 provided a hole to load the HD20 INIT, by name or TYPE. Since the 512K will run System 5, clearly all versions of System 4.x have a hole for both the HD20 INIT and the MacIIHD20 INIT. Why the new driver then – did the new 68020/30 ROMs require different patch points? I would be curious to see if the old HD20 INIT would work on a Mac II running 4.x connected to a HD20 as described above. System 6, most certainly creates the proper hole. At the same time, it likely closed the original HD20 hole. Apple made the decision to officially drop support for the HD20 with System 6 and perhaps this is why, as there would have been little accommodation for it to support a 512K, even though many have indicated no problems with a 512Ke. I suspect RAM based HFS support would have had to be re-written with System 6, which doesn't make much sense for an obsolete product. As enticing as this INIT is, I seriously doubt whether it will solve this problem on a stock 512K if it's an HFS support issue. But it's always worth a try ...

If this analysis is correct, the real question is was the original patch hole for the HD20 INT closed System 6 arbitrarily, or was it due to an incompatibility? If the former, then the hack would be to make System 6 aware of the original HD20 patch point again. Since the 512Ke loads System 6 just fine and the only differences are an additional 64K in ROM, which is mostly HFS and SCSI drivers, what else could System 6 failure to boot be but the lack of HFS code? I know System 7 requires a SCSI disk and will not use an HD20, but could System 6 require the SCSI code to be present as a condition of startup (i.e. it expects the ROM to scan the SCSI bus and report back so System 6 hangs when the 64K ROM doesn't do this)?

Apple further refers to a special INIT which allows the HD20 to be mounted by the SE/30 and files copied from, but not written to. http://docs.info.apple.com/article.html?artnum=6182

Click to expand...

I've been begging for someone to post that for ages. If any of you out there have access to that magical INIT, please PM me! I wish to test and offer the classic Mac community a complete report.

Click to expand...

Anyone know what the exact file name is for that init? Is it named the same as the standard HD20 init, but a different version, or does it have its own special file name.

Hmmmm. Would it have been included on old developer disks? I have a pile of those I bought on Ebay.

Oooops. Never mind. I posted before I read the next post after that one.

I'd read the TIL article to which Mac128 refers too. All the documentation suggests that the HD20 transfer INIT is a temporary hack that you would not wish to be permanently installed.

My speculation is that the transfer INIT disables polling on the signal lines that are explicit to the SuperDrive IWM. So it provides enough functionality for a data transfer (ie a Finder copy) but other disk activity may require signals that are being disabled. Formatting a floppy disk is a case that the transfer INIT may not be able to handle.

BTW, Mac128, thanks for the test of a 400K MFS disk in a Plus. It destroyed my theory completely but it is good to know the facts.

It's also important to keep in mind that the highest System file version I could use to boot off an 800k MFS floppy is System 4.1. However, I can use version 4.2 on a 400k MFS floppy. Go figure!

So it provides enough functionality for a data transfer (ie a Finder copy) but other disk activity may require signals that are being disabled. Formatting a floppy disk is a case that the transfer INIT may not be able to handle.

Click to expand...

Yes, in fact that would handily explain why they recommend you do not write to the drive. Perhaps what they've disabled affects not just formatting a floppy in the SuperDrive but writing to and attached floppy bus disk, including the HD20. Either way, I doubt this INIT would do much toward helping the 512K boot System 6. I fear the answer lies more in what's missing from the 64K ROM and the HD20 INIT, or the fact System 6 ignores the INIT altogether.

So what does the 128K ROM add that the 64K ROM doesn't have, that System 6 needs?

800K Driver – I booted the Plus off a 400K drive withe both the HFS & MFS version of System 6, so it doesn't need an 800K drive.

HFS – I booted the Plus off of an MFS disk. Are there resources in the System folder that are stored hierarchically so that HFS is actually needed to read them? Otherwise everything is at the root level and HFS shouldn't matter.

SCSI – Does System 6 require confirmation of the presence of SCSI or not ... a prelude to System 7's requirement of SCSI?

That's all I can think of? What else is missing that System 6 could possibly require?

To answer my own question I just took a look at Inside Macintosh IV and it turns out there could be any number of issues hanging System 6. The Sound, disk and serial drivers are stored in 64K ROM but not as resources. Also, the Apple Talk drivers were not in the 64K ROM. Since System 6 makes much more out of AppleTalk, that could be check it fails. It also makes reference to a number of QuickDraw bugs in the 64K ROM.

 

The reality of these facts is that System 6 may be expecting any number of things in the 128K ROM, no longer compensated for by dropping support for the 64K ROM, which the HD20 INIT never compensated for anyway and therefore System 6 will never be possible on a 512K without a custom INIT to load all of the 128K ROM code substitutions into RAM, the net effect being that there would be little usable RAM left for applications and therefore somewhat pointless.

It's also important to keep in mind that the highest System file version I could use to boot off an 800k MFS floppy is System 4.1. However, I can use version 4.2 on a 400k MFS floppy. Go figure!

Click to expand...

Will that 800K MFS disk boot on a 128K+ ROM? Since Apple really shouldn't have expected anyone to be running 800K MFS partitions, there shouldn't be anything in the system folder to exclude it. Could you ResEdit compare the System files to see if there are any obvious differences? I can't imagine why 4.2 wouldn't boot off of an 800K MFS disk but boots fine on a 400K disk. Especially if 4.1 boots off an 800K MFS disk and I trust they are roughly the same size?

I will compare 4.2 and 4.1 with ResEdit when I have time after work, but I must admit I don't know what I am looking for, and there will be numerous differences.

As to the SE/30 INIT that allows the HD20 to be connected, I personally would still have use for it. I would use it to make easy backups of my HD20 via my SE/30. In this day and age, it doesn't make sense to use floppies for such backups, saving a 20MB hard disk to a modern drive is nothing! But alas, until I get a copy of that INIT, I cannot have this wonderful convenience!

Lastly, as I requested in one of my previous posts in this thread, if someone could be so kind as to send me a copy of System 4.3 on an original disk image, I would be grateful! The version I have didn't come from a disk image -- I found it on the web and it was simply compressed in a folder. I think it may have been corrupted, which is why that System file won't boot any disk on my Mac (400k or 800k) or any format (HFS or MFS).

Yes, in fact that would handily explain why they recommend you do not write to the drive. Perhaps what they've disabled affects not just formatting a floppy in the SuperDrive but writing to and attached floppy bus disk, including the HD20.

Click to expand...

Well spotted. It is more likely that the transfer INIT brain damages the 64KB ROM floppy interface rather than the 128KB+ ROM interface. The document talks about transferring data from an HD20 to other media. Given the era, this would imply that you could transfer data from the HD20 to a 1.4MB floppy disk.

This second theory is supported by the warning that external floppy drives should not be connected.

Either way, I doubt this INIT would do much toward helping the 512K boot System 6. I fear the answer lies more in what's missing from the 64K ROM and the HD20 INIT, or the fact System 6 ignores the INIT altogether.

Click to expand...

Me too, as they used to say in the AOL era.

It's also important to keep in mind that the highest System file version I could use to boot off an 800k MFS floppy is System 4.1. However, I can use version 4.2 on a 400k MFS floppy. Go figure!

Click to expand...

A possible explanantion is the way that programmers work. When you are asked to modify existing code, you go back to the version that looks "cleanest". By cleanest, I mean the version that the programmer considers can support recently introduced features whilst being easy to update. You may review several versions of the code before making a choice. After making that choice, you might need to copy, paste and edit some code for existing features into your new version.

And it is during the copy and paste exercise that changes get missed. Perhaps the original programmer for System 4.1 was told to drop support for a feature that relied on a 64KB ROM. But when System 4.2 was being written, the programmer reverted to earlier code and incidentally included a discontinued feature.

This is pure speculation, but it is based on real life experience.

It is more likely that the transfer INIT brain damages the 64KB ROM floppy interface rather than the 128KB+ ROM interface. The document talks about transferring data from an HD20 to other media. Given the era, this would imply that you could transfer data from the HD20 to a 1.4MB floppy disk.
This second theory is supported by the warning that external floppy drives should not be connected.

Click to expand...

Actually that article was written contemporarily to the Mac II and specifically discusses the IWM. Another issue with that Mac is this hack has you basically connecting the HD-20 to an internal floppy disk. Meaning the Mac II had 2 internal enablers and no external ones. Since the HD-20 is being connected as an internal drive it is likely the Mac II ROM cannot support an additional floppy drive, particularly an external one, which is what the HD-20's internal IWM supports. Only the SE & Portable support two internal drives as well as an external drive. So at best, you could back up the HD-20 to the 1st 800K floppy disk. It specifically says what would happen of you try to write to the HD-20, which is: it will take a long time. It doesn't say not to do it, so I would think the internal floppy drive would be fair game as well. I must have gotten this article mixed up with the SE/30 one.

The SE/30 article specifically discusses transferring to the internal SCSI drive. The SWIM chip should support the HD-20, but it is being enabled via a hack and the SE/30 article also warns of writing to the HD-20, though it doesn't prohibit connecting an external floppy drive. Nevertheless who knows what affect this driver has on the floppy bus in general.

What is odd between the two articles is that the SE/30 uses the IIx ROM, derived from the II. This suggests the IIx ROM added support for an internal and one internal OR external floppy Superdrive if my theory is correct and would therefore have no problems supporting an external drive. However, there was no restriction towards writing to the HD-20 on the II, whereas on the SE/30 it's taboo. Is this because the HD-20 has it's own IWM chip onboard? Are SWIM & IWM chips incompatible at least with respect to this ROM patch? The HD-20 is endorsed for use by Apple on the Portable which also has a SWIM, but also supports the HD-20 natively in ROM.

Charlieman, you've raised more questions than you've answered!

The same kind soul and an outstanding contributor to the classic Mac community, has been gracious in offering me a copy of the MacIIHD20 extension mentioned in this thread. I tested that extension today in conjunction with my SE/30 and HD-20. I put two photos and a complete report under each of those photos on Flickr here.

Please read the comments under both of my photos (some of you have looked at my photos in the past, only to PM me and say you couldn't understand what the photo was about -- PLEASE READ!). Please also click the links I have provided in my photos, as that takes you to relevant information.

All said, the MacIIHD20 extension doesn't work to allow mounting of the HD20 on the SE/30. I need the Apple "INIT Utility" for that. And if one of you out there have it, please PM me for the sake of the classic Mac community. I am dying to test that extension and provide a complete report.

UPDATE: It was suggested to me offline that I test under System 6, not System 7. (As written in the comments under my Flickr photos, I used System 7.5.5 in this test.) I just finished testing under 6 and added details of that test under my photo. See that Flickr photo for details. Simply put, System 6 is NOT the solution here.

I tested that extension today in conjunction with my SE/30 and HD-20.UPDATE: It was suggested to me offline that I test under System 6, not System 7. (As written in the comments under my Flickr photos, I used System 7.5.5 in this test.)

Click to expand...

This is why:

http://docs.info.apple.com/article.html?artnum=9856

Also, it is not clear that Apple calls their INIT Utility "INIT Utility". So looking for such a generic name may make one crazy. The document states:

Additionally, we have included an INIT Utility that reads the data from theHard Disk 20 and puts it on the internal hard disk of the Macintosh SE/30.

Click to expand...

They are not specific about where they have included the utility. One might imagine that it appears on SE/30 Install disks. As the article is dated November 01, 1990, perhaps it is on the System 6.0.7 upgrade disks as an "extra". The IIsi was also released around this time and Developer's notes also reference an "INIT resource" to run the Hard Disk 20. I would expect to find the INIT on the IIsi install disks as well.

Apple references System 6.0.3 in that article as well which is likely when the issue came up again (clearly it had already been an issue in '87 with the Mac II) with the release of the SE/30 in '89. It looks like the INIT paragraph was tacked on later as more HD20 users were migrating to SE/30s and Mac IIs. So I would expect the INIT to show up on any software from 6.0.3, to System install disks that shipped with any Macs that did not have built-in support from 1989 through 1990, which includes the IIx, SE/30, IIcx, IIfx, IIsi and LC and Sytem 6.0.7.

The fact that the MacIIHD20 didn't work with the SE leads me to believe that the II with its 68020 processor may be the reason. Therefore the IIx which is basically an SE/30 may also have the INIT in its system install disks. Possibly even on the 6.0.2 general release.

The MacIIHD20 INIT came off of a 1989 Developer's CD. So I would expect the SE/30 version to be on a newer Developer's CD as well. Because, if one had to get it from a dealer, then we may screwed!

Oddly, Apple posts the exact same article without the INIT Utility comments dated 1992.

http://docs.info.apple.com/article.html?artnum=3501

Could it be that someone at Apple thought the INIT worked with the SE/30 and some helpful employee tacked that on, as well as Apple intended to provide it for the IIsi, but never did. Then in '92 when that second article was reviewed for accuracy, someone deleted the INIT comments because they didn't really apply to the SE/30 afterall, but failed to delete the original article? If so, think of how many hours have been wasted on this pursuit!

They are not specific about where they have included the utility. One might imagine that it appears on SE/30 Install disks. As the article is dated November 01, 1990, perhaps it is on the System 6.0.7 upgrade disks as an "extra". The IIsi was also released around this time and Developer's notes also reference an "INIT resource" to run the Hard Disk 20. I would expect to find the INIT on the IIsi install disks as well. It looks like the INIT paragraph was tacked on later as more HD20 users were migrating to SE/30s and Mac IIs. So I would expect the INIT to show up on any software from 6.0.3, to System install disks that shipped with any Macs that did not have built-in support from 1989 through 1990, which includes the IIx, SE/30, IIcx, IIfx, IIsi and LC and Sytem 6.0.7... the IIx which is basically an SE/30 may also have the INIT in its system install disks. Possibly even on the 6.0.2 general release.

Click to expand...

I have all four System 6.0.5 install disks. One is named System Tools, but even on that disk I cannot find any "INIT Utility" or anything else that would perform the same task. I thought it could be on the 6.0.3 System Tools disk, as is clearly alluded to in that Apple Article, but I couldn't find it. See for yourself, as Apple makes 6.0.3 disks available for download here.

Another issue with that Mac is this hack has you basically connecting the HD-20 to an internal floppy disk. Meaning the Mac II had 2 internal enablers and no external ones. Since the HD-20 is being connected as an internal drive it is likely the Mac II ROM cannot support an additional floppy drive, particularly an external one, which is what the HD-20's internal IWM supports.

Click to expand...

The Mac II's inability to support an external floppy drive is a physical one: lack of external floppy port. As far as the mac is concerned, the floppy drive could be anywhere. Various third party manufacturers manufactured adapters (basically a ribbon cable and a plate that fitted on the back of the Mac II) that enabled external floppy drives. The manufacturer that sticks in my mind is Kennect (sp?) who made an odd ball high density floppy drive. Very collectable and technically interesting.

I have all four System 6.0.5 install disks. One is named System Tools, but even on that disk I cannot find any "INIT Utility" or anything else that would perform the same task. I thought it could be on the 6.0.3 System Tools disk, as is clearly alluded to in that Apple Article, but I couldn't find it. See for yourself, as Apple makes 6.0.3 disks available for download here.

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Yeah, I have a set of 6.0.4 release disks as well as a set of 6.0.5 pre-release disks and have certainly downloaded the 6.0.3 disk set. I was gambling for that "extra" disk that may have been included in the box which might not be considered part of the "official" release. We need someone with original system install disks to weigh in, do we need to post this in the Mac II forum as well? If the INIT is not on one of the specific System install disks shipped with the Mac, then it must have only been available from the dealer upon request of the specific problem. Hopefully, today, it is on a later Developer CD at a minimum.

Back on topic, back in January of 2005 someone over at Wikipedia seems to have already confirmed what we have re-learned about the 512K's ability to run System 6. http://en.wikipedia.org/wiki/Macintosh_512K Unfortunately, they were a random visitor who did not log in to provide a traceable path of inquiry, which is one of the reasons Wikipedia is an unreliable source at best. Interesting that they reference the exact limitations you found yourself, JDW. It is most frustrating that no other reliable source can be found to confirm it and that the Mac512.com site has such glaring contradictory information about the very Mac from which it derives its eponymous URL.

he Mac II's inability to support an external floppy drive is a physical one: lack of external floppy port. As far as the mac is concerned, the floppy drive could be anywhere. Various third party manufacturers manufactured adapters (basically a ribbon cable and a plate that fitted on the back of the Mac II) that enabled external floppy drives.

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I've been looking at too many block diagrams. I thought there were specific enable lines that were polled to determine operation that might be encoded into ROM. I had often thought the lack of external drive ports was a non-issue on two internal drive Macs and clearly I was right. I suppose Apple thought people would not keep peripherals from previous computers so moving all drives internally and dropping support for the HD-20 would not be an issue. On the other hand, they would have saved themselves some headache if they had simply included a third external port as with the SE and included the HD20 driver in ROM – especially considering the II's cost. However, could the II's ROM have limited it to only two disk drives? Given that the HD20 was not supported on the II and had to be enabled by a patch, which admittedly is not fully implemented, could that have somehow limited the HD20's ability to daisy chain an external floppy drive, thus the warning (i.e. the INIT is tricking the II into seeing the HD-20 as a giant internal floppy and it doesn't enable the HD20's native ability to support a third)?

So we have an INIT that is supposed to patch an HD20 driver into the Mac II ROM, which won't work on an SE. What other variables are there besides ROM code variations between the 68020 & 68030 processors that would account for its failure? The II shipped with System 4.x and given the date of the article, the INIT almost certainly applies to 4.2. Since the SE/30 (or IIx) can't run 4.2, there's no way to test this variable, except to possibly check its compatibility with System 6.x on a Mac II.

Here's a blurb about that Kennect drive ... http://www.macdrivermuseum.net/disk.shtml – why haven't we heard of this thing before!

someone over at Wikipedia seems to have already confirmed what we have re-learned about the 512K's ability to run System 6. Interesting that they reference the exact limitations you found yourself, JDW.

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"Confirmed" or "Copied out of the 68kMLA forums." Seriously, as you point out, there's no way to verify that the Wiki poster did the tests himself. I am going to guess he (or she) did not. It often makes people feel good to extract info from one site and post it on Wiki, even if their name isn't in lights. Gives them a sense of power. So I don't give that Wiki entry too much credence. Indeed, the photos used on that Wiki entry have been used to sell compact Macs on EBAY, even before they were used on that Wiki entry!

IMPORTANT UPDATE:

First of all, I screwed up royally. I had relied on my memory, the name of my 400k floppy disk and the name I wrote on that disk label to tell me the System file version. Bad idea, because I was wrong. I wasn't getting System file 4.2 to boot my Mac 512k after all. It was version 4.1 all along! (I used a SysVer app to confirm the actual system file version today.)

 

I discovered this only today, after a kind soul directed me to the download location for System file version 4.3. I put that on an 800k MFS disk, but it wouldn't boot (gives me an ID=12 error at boot time). I then deleted some of the fonts and DA's in the 4.3 System file so that it and Finder 6.0 would fit on a 400k disk. But S4.3/F6.0 would NOT boot my 512. I then tested my so-named "4.2" floppy and found that it was in fact 4.1. When I then corrected the problem, copying over System file 4.2 onto that same 400k disk, I got the same ID=12 bomb at cold boot as I do with 4.3.

 

So what this means is, neither System file 4.2 nor 4.3 will work on the stock 512 with 64k ROMs. But various Finder 6.x versions WILL work with many older systems through S4.1 though.

 

Now the question is, why won't 4.2 and 4.3 and higher Systems work on the 512? More specifically, why won't they BOOT the 512. I can use those System file versions just fine if I first boot off another disk and then double-click an app on the S4.2 or S4.3 disk, such that control of the Mac is handed over to S4.2/S4.3. It's just that I cannot BOOT from S4.2 or S4.3.

 

Thanks again for the kind soul who has assisted my testing thus far!

Now the question is, why won't 4.2 and 4.3 and higher Systems work on the 512? More specifically, why won't they BOOT the 512. I can use those System file versions just fine if I first boot off another disk and then double-click an app on the S4.2 or S4.3 disk, such that control of the Mac is handed over to S4.2/S4.3. It's just that I cannot BOOT from S4.2 or S4.3.

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When you hand off to the Application disk System, does it return you to the 4.2/4.3 System's Finder desktop when you quit or does it crash like you found on the System 6.x versions you tested. That would be an important distinction.

AppleShare v.2.0 ships with System 3.4 & Finder 6.1 for the Mac 512Ke. Also the System 7 LaserWriter driver is fully compatible with the 128K/512K AppleTalk Systems and up. So the newer Finder and drivers seem to be more fully compatible with earlier systems than the newer system files to the earlier ROMs.

System 4.2 & 4.3 comprised System Software 5.x which introduced the MultiFinder that was at the core of System 6 use. Perhaps the system changes required to support MultiFinder and other new background operations were incompatible with 64K ROMs and there was little incentive to rewrite the HD20 INIT to support a machine that System 4.1 had already technically left behind with its 1MB limitation. Frankly, I wouldn't think a 512K could run RAM-based HFS and disk drivers, MultiFinder and background networking as well as any useful applications. Though the 512Ke can support System 6 and presumably MultiFinder, I'm not sure how useful it would be to attempt to run say MacWrite & MacPaint at the same time. The 512K usefully supports System 6.x with ample RAM when used traditionally, in part thanks to the 128K ROMs.

Also, System 5 jumped from around 500K to over 2MB for a standard install. Even the System file alone jumped over 100K on the startup disk between System 4.0 & 4.1. Those increasing System sizes alone would be enough to cut out anything considered obsolete. I've found Inside Macintosh IV absolutely fascinating reading as it details the changes between the 64K ROM and 128K ROM. One of the most remarkable differences that I was not aware of is that in addition putting a number of items in the 128K ROM formerly in the systems written for the 64K ROM, a large amount of 128K ROM redundant code was however left in the newer systems in order to maintain compatibility with 64K ROMs. This was not HD20-type INIT, though it arguably should have been, but rather written into the system code used on every new Mac. Had this redundant code been included in an INIT-type situation one could simply have not installed it on a Plus and above, then again that might have slowed the 64K ROM Macs even more and taken more RAM on those Macs, as well as making future updates more difficult. So clearly Apple made the choice to strip any unsupported code, presumably to fight system bloat, maximize compatibility and improve overall speed with current systems. 4MB was still a real RAM ceiling for most of its product line at this time and every Kilobyte freed from system use was available for applications.

Besides, Apple had a very simple 800K Drive upgrade kit for your Mac 512K if you didn't want to be left behind. Why should they continue to break their backs to distribute free system software to support consumers who were unwilling to buy more Apple products to the detriment of those who were?

Besides, I am not so much interested in running System 6 on a 512K as I was curious about what it could actually handle. I think now we know and hopefully a pretty good understanding of why. For me the joy of 64K ROMs is running those native MFS systems and early HFS Systems that support AppleShare. SCSI only holds appeal for me to the extent that I could eventually use a flash drive on it. However, I would settle for a serial flash drive interface for the HD20 drive mechanism. Anybody interested in constructing one?

When you hand off to the Application disk System, does it return you to the 4.2/4.3 System's Finder desktop when you quit or does it crash like you found on the System 6.x versions you tested.

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The hand off is seamless. I just double-click an app on the 4.2 or 4.2 floppy, the app loads (at which time the hand off takes place), and then when I return to the Finder, I see the 4.2 or 4.3 disk is the boot disk. Launching SysVer confirms this.

So you see, I get no crashing for hand-offs that occur after boot, but I just cannot boot from a 4.2 or 4.3 disk. It's very odd.

And no, I did not include MultiFinder in the System Folder during any of my tests (there wasn't enough disk space on my 400k floppies to do so).

I am not crying over the fact the Mac 512k cannot run System 6 (or 4.2 or 4.3, from what it seems). I am just interested in confirming what can and cannot run on the 512k, and then discuss all the reasons why (as Mac128 has done in this thread).

As to getting SCSI to work on my 64k ROM Mac, or getting serial flash to work, I am all for it. Yes, I know many will try to say it's not cost effective for someone to manufacture a couple hundred pieces of such a system for sale to the classic Mac community. But it would be nice to see a set of detailed instructions on how to build something like that as a hobbyist. But then again, if there are drivers or other software that would be required to make it run, then we would need to rely on a 68k programmer to put that together for us.

The hand off is seamless. I just double-click an app on the 4.2 or 4.2 floppy, the app loads (at which time the hand off takes place), and then when I return to the Finder, I see the 4.2 or 4.3 disk is the boot disk. Launching SysVer confirms this.

So you see, I get no crashing for hand-offs that occur after boot, but I just cannot boot from a 4.2 or 4.3 disk. It's very odd.

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So where does that leave us? The Mac 512K can boot up to System 4.1 and can hand-off to System 4.2 & 4.3, but can't run System 6 in any manner (except single application hand-offs, which is sort of pointless).

Though it would be nice to know exactly what is hanging up System 5 during boot, most likely it is a resource which is looking for something in a specific ROM location which is not in the 64K ROMs. I assume you tried both with and without the HD20 INIT. In which case, the only recourse left is to compare System 4.1 & 4.2 to see if there are any major differences which can be disabled allowing it to boot without affecting the system operation. If not something that can be easily removed with the FONT/DA Mover, then the resulting system would be a hack beyond the capabilities of the casual user.

I don't really have a problem with handing off to 4.2 & 4.3 as long as they are stable afterwards. For instance In order to use the HD20 you have to boot from a 400K disk anyway. So startup with System 4.1 and install 4.2 or 4.3 on the HD20. This should have the same effect. If it does not, then I may suddenly be curious again as that means the hang up is at a higher the ROM address than I would expect. A 512K using systems that large should be running off a hard drive anyway.

The one final speculation I will toss out is that sometimes when I create a disk by dragging known good files to a new disk, rather than using DiskCopy or an installer, I end up with a system that will not boot, but will take over when an application is launched from it. I have read that in such cases it's a matter of "blessing" the system, which in the early days sometimes meant going back into the file headers with a disk editor and putting back certain data that somehow got stripped during the copy process. Either way, at this point we are looking at code level disk details.