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64K ROMs and 800K floppy


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Here's a slightly strange one. My 128K mac had been upgraded to 128K ROMs and internal 800K drive. Since my Plus covers this space well and I wanted a representative machine with the 64K ROMs I downgraded it, but kept the 800K drive (because I don't have a 400K drive and it appears to work perfectly). However, when I connect an external 800K drive, although both drives work, the INTERNAL drive motor starts making regular noises.

 

Is this just another manifestation of the standard "cut-wire-x" thing with 800K drives and the 128K/512K macs? Or something different?

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There are heaps of very cheap second hand copies of the Dead Mac Scrolls available in the US - I got mine (perfect condition with disk!) from www.abebooks.com. The other Pina book for early macs is much harder to come by, but I have it too and will look into it to see if I can find where this is mentioned.

 

Thanks

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Checked what Larry Pina had to say, his solution is "Upgrade to the 128K Roms" :-)

 

However, he then talks about pin 20, and that is consistent with Tom Lee's paper as well, so I will try disconnecting it and seeing if things get better.

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Here's a slightly strange one. My 128K mac had been upgraded to 128K ROMs and internal 800K drive. Since my Plus covers this space well and I wanted a representative machine with the 64K ROMs I downgraded it, but kept the 800K drive (because I don't have a 400K drive and it appears to work perfectly). However, when I connect an external 800K drive, although both drives work, the INTERNAL drive motor starts making regular noises.

 

Is this just another manifestation of the standard "cut-wire-x" thing with 800K drives and the 128K/512K macs? Or something different?

 

Apple did sell an upgrade kit to turn an older compact into a Plus. One of my Pluses is actually an older machine that has been upgraded. It sounds like you may have an amalgam of parts from the original machine and an upgrade kit. If that's what it is, I don't know how it's all working together, but something definitely isn't right. That may be the reason why your internal drive grinds away when there is a disc in the external one. You may need to put those 128k ROMS back in or get a 400k floppy. The 64k ROMS may be having problems with the 800k floppies. You may also have a Plus motherboard in there that is also having a disagreement with the 64k ROMS since it was never designed to work with those, either.

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I think I posted in detail about this in the past, but my memory fails me and I am not able to pull up that post via Google. If only there was a backup before this site went down!

 

What I can say is that I have a Mac 512k with the original 64k ROMs and I also have a 400k internal drive, 400k external drive, 800k external drive and a HD20. I have tested all these drives together, even testing an 800k internal drive too, all with the 64k ROMs installed. After consulting a Larry Pina book, I cut the appropriate wires on the 800k external drive. But despite this, the LED on that drive still flashes every few seconds at boot time (before any disk is inserted). Every time the LED flashes, you can hear the motor spin (showing it is trying to access a disk). This will continue forever until you put in a floppy. I suppose it won't damage anything, but it is annoying, and I spent hours going over schematics and Pina books in vain trying to find a solution. My posts here resulted in zero ideas from anyone else on how to solve it either.

 

So what I am saying is that even if you cut the right wires, you will likely have this external 800k drive access issue appear. Hearing that motor and seeing that LED flash every few seconds bugged the heck out of me.

 

Of course, if you connect the HD20 and then connect your 800k drive to that, you won't have the LED/access problem anymore. The reason is because you cannot boot off that 800k drive until you first load a disk into your internal drive! That's the secret catch of using an HD20!

 

Also, when you use the 800k drive without loading the HD20 init, you can still use the drive just fine. Most sites and books say this cannot be done, but I know first hand it can be done! The catch is that you will hear grinding sounds coming from your 800k drive. It will be a bit slower too. But if you then boot off a floppy with a HD20 init on it, the 800k drive will suddenly stop grinding and access speed will be greatly improved (on the 800k drive).

 

I am now awaiting delivery of a Mac I bought off EBAY with a 20MB GCC HyperDrive in it! The HyperDrive was the first of its kind in that it allowed you to put a hard disk INSIDE your Mac! That didn't become possible from Apple until the SE.

 

UPDATE: I found my 800k drive connector photo and uploaded it to Flickr with a detailed description here. I also found a cached version of the detailed thread on this subject, which was sadly deleted when this site went down several weeks ago. Reading through that thread and having a look at my photo should get everyone up to speed.

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Yes - I remember that thread, and the outcome. :-(

 

The 128K upgrade is straightforward - you just put in the two 128K ROMs and an 800K drive. That had indeed been done to my machine, but I put 64K roms back in. Nothing is wrong with that, but there is clearly some issue with the drive combinations. I may try the wire cutting exercise and hope I am luckier than JDW, but I can't use the HD 20 init because of only having 128K of RAM.

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...hope I am luckier than JDW...

If you are "luckier," please post all the pertinent details in this thread. But I am skeptical if you will be; for that would mean the hardware I have is defective somehow, and I am simply not seeing any other anomalies that would indicate such to be true.

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  • 3 weeks later...

To supplement what I posted above about the external floppy drive LED flashing problem, here is a

showing the LED flashing. The first few seconds of the video shows the LED flashing continually until a disk is inserted. Still curious if there is a way to solve this issue without resorting to 128k ROMs.
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  • 2 months later...

It depends on the drive. See my advanced file transfer tutorial at http://www.Mac128.com

 

Only one 800K drive can be used as a boot drive. The Apple 3.5" drive made for the Apple IIGS. The original 800K drive made for the MacPlus needs the HD20 Init to be recognized and will actually cause the 400K drive to pulse even with the INIT. But the Apple 3.5 is totally compatible.

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Make sure it's NOT a UniDisk 3.5" or else you'll have to modify it a little bit. UniDisks are easy to spot because of their unique eject button and white IIc colour. They're not that common but just in case you find one I suggest you look elsewhere for the aforementioned 3.5" drive.

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Scott, I appreciate the tip. However, my drive is not white, nor is it an Apple II compatible UniDisk drive. My 800k external drive is model A9M0106. I have posted a photo of my drive and a detailed commentary on it. You can read that I also disconnected some wires in an attempt to solve the LED flashing problem, but it didn't work.

 

Mac128, you say the 800k drive could cause the 400k internal drive to pulse, but I never had that problem. Perhaps it is because I disconnected those two wires (as mentioned in my Flickr commentary) on my 800k external. In any case, the only problem I have is that the 800k external LED flashes and it spins the motor when the LED flashes (i.e., "disk access attempt") every few seconds as shown in my video.

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Pina details the pulsing problem clearly, which you describe as regular noises. It is the primary problem with using 800K drives with 64K roms. This is one of the reasons I specifically mention on my website tutorial that your drive is the only one that's compatible with the 64K ROMS. Since the 800K drives don't use the speed control for the 400K drives, all versions are disconnected at the socket head or the cable. Not sure which method is used on the external 800K drives, but cutting wires on your drive would not affect this at all. Most likely the disk access issue you describe is some aspect of the dual purpose the drive served for the Apple II series, i.e. checking the drive for the presence of a disk. On my A9M0106, the drive only exhibits the disk access/flashing light until a disk is inserted somewhere in the system, either internal or external. Then all is normal. Is your problem that when the system is on and no disk are in the drive it exhibits this behavior? If so, what's the problem? Just insert a disk and get on with it. Also, your external 800K drive as you know will boot your Mac and will format a double sided disk to 800K MFS. You don't need the HD20 INIT at all to use two of these 800K drive models to capacity, only to read/write HFS. The HD20 is required on the older 800K drives to even see them. Just so I'm clear ... is the problem you're having related to the pulsing when the external drive is connected, or the external drive itself?

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Pina details the pulsing problem clearly...

Indeed. I have the book you speak of and have read it through three times! It was one of several sources I used to determine which wires to cut on my drive.

 

On my A9M0106, the drive only exhibits the disk access/flashing light until a disk is inserted somewhere in the system, either internal or external. Then all is normal.

Yes, that is correct. You are experiencing exactly what I am. But my pursuit has been to eliminate that LED flash/disk access every few seconds because I don't like it. I want the drive to remain silent until I decide to put a disk in one of the drives. I doubt this drive access will hurt anything, but it bothers me. "Just insert a disk an get on with it" is not a "solution to the problem" in my eyes. I have no other computer that flashes a red light at me and spins a motor every few seconds until a disk is inserted, so I don't care to have this setup do it to me. No doubt, there is a technical reason why this happens, and I am in search of that reason. Because if I know what that is, I can possibility solve it. And again, "just put in a disk" is not a "solution." If anything, "just put in a disk" is a mere bandage that masks the root problem.

 

You don't need the HD20 INIT at all to use two of these 800K drive models to capacity, only to read/write HFS.

I was actually one of the first to post this on the net quite a long time ago. Until that time, there was a lot of bogus info (and still is) on the net saying you have to have that INIT or you cannot use the drive. That's wrong. You can use the 800k drive without the INIT, but it will make different sounds when accessing the disk. It sort of sounds like grinding noises. I don't think this is a problem at all. It's just the computer treating the drive like a 400k drive instead of an 800k drive. Also, without the INIT the speed is a bit slower too. With the HD20 INIT (or 128k ROMs), the 800k drive read/write speed accelerates tremendously (and there are no grinding noises either). I would refer you to my original post on this subject, but alas it was on this forum prior to the hard drive crash. That thread has been completely deleted.

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First I would refer you to this if you have not read it: http://docs.info.apple.com/article.html?artnum=1605

 

Pina's Macintosh Repair & Upgrade book is invaluable to the old Mac user. However, it is often unclear and contradictory to published Apple info (not unusual since Apple often contradicted itself). In particular I would ask you to re-read Pina's statement about the speed signal in the last paragraph of page 193. Like many statements he makes in the book you really have to read it several times to understand why he's saying it. However, he gives this info so you won't mix up your internal drives and cables. I'm afraid you mis-interpreted this to mean you had to physically cut wires on your drive, which already had taken Pina's observation into account. Besides, Pina's advice is for internal drives and as you know the external pin-outs are completely different.

 

That said, it might be worth a look at the Apple IIGS 800K floppy controller pin-outs to see if there is a signal line that might be cut which would prevent the LED flashing and disk access.

 

Now, as to your problem ... thank you for clarifying. You mention in your initial post that the internal drive "pulses". So I wasn't sure which problem you were trying to fix. Frankly the flashing LED is the least of your problems since that goes away after the system is in use and the pulsing does not (at least with an 800K internal drive, the 400K works fine) ... so much for a quiet system. This is on of those things that I shake my head at because I know what you are saying. It bothers me too, like dust under the refrigerator. Frankly (and I mean no offense here), but the time the Mac is on without a system disk working is so brief as to be a negligible issue ... particularly when you consider the following:

 

What you and I are both doing is a HACK. PERIOD. The 800K drives may well work with the 128K (and indeed Apple intended this from the beginning when the double sided drives became available, but their strategy changed when they created HFS), BUT once Apple changed to HFS, they made no attempt to make them compatible with the 64K ROMs without the HD20 INIT and HFS support. For whatever reason the A9M0106 and MFD-51W-03 drive doesn't care, possibly to enable compatibility with the Apple II. Notice Apple says specifically NOT to put the older drives in the A9M0106 external enclosure. Therefore, AS A HACK, you are using something that is not designed to be compatible with your system and therefore is likely to do lots of things that bothers you. I personally have banged my head against a wall simply because I wanted something to work in a manner in which it was never designed to work, simply because it bothered me. That said, certainly Apple must have known the A9M0106 worked without the HD20 with 64K ROMs (as well as the MFD-51W-03 drive). Since very little is known about the exact release dates and discontinuation of the external drives or the rational behind Apple's design, it has been assumed Apple intended the A9M0106 as a universal replacement for all of their previous 400K & 800K drives and as such, an original 128K/512K Mac which still needed a 400K drive could buy it as a replacement external with an eye toward upgrading in the future. If so, they must have also known the LED would flash and drive accessed until a system disk was inserted with or without the HD20 INIT. And just so you know ... when the A9M0106 is used with a Mac Plus, the LED flashes once upon startup as it is being accessed by the Plus looking for a startup disk – the difference obviously being that the 128K ROM knows how to handle the drive response and patiently waits. With that in mind, I doubt cutting any cable will stop the problem without rendering the disk useless. All in all the continual disk access at startup is a small trade off for use with the 64K ROM.

 

I do hope you find a solution, however unlikely and I must admit your post has peaked my curiosity about testing various combos of my external drives with my 128K to get to the bottom of not only the flashing LED but also the pulsing, which Pina himself fails to explain (I mean really, if the speed control is already isolated from the drives, then why do they pulse?).

 

Finally, I am thrilled you are helping to clarify the mis-information on the web. I am certainly not looking to take credit as discovering this, or certainly overshadow your accomplishments ... if anybody deserves the credit it's Larry Pina! My goal is to clarify the mis-information and to make working with an old Mac in an Intel world easier for the Mac enthusiast. Particularly when it comes to pre-system 6 and MFS systems. I will not state anything that I myself have not tested. That said, I must tell you that while this 800K drive works without the HD20 INIT, the actual 800K External Drive M0131, sold for the 512K & Mac Plus will NOT work. Also, on a 64K ROM system, you CANNOT use HFS formatted anything without the HD20 INIT which will not load on a 128K. On a 512K, even with your drive, you must have the HD20 Init in order to write HFS formatted disks with a System 2.1 or later. System 2.0 and earlier will write MFS ONLY with or without the INIT. So, be very careful about saying a thing is right or wrong unless you've tested it personally. Also, your posts seem to indicate that you are limited to 400K without the HD20 Init. on your drive and that's how mis-information gets around.

 

In any event I look forward to your future discoveries ... happy hacking!

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I'm afraid you mis-interpreted this to mean you had to physically cut wires on your drive, which already had taken Pina's observation into account. Besides, Pina's advice is for internal drives and as you know the external pin-outs are completely different.

 

I don't think JDW misinterpreted it. You actually *do* have to cut one or more connections on the ribbon cable in some cases. Late-run drives evidently (re)used the pins for other functions. So, if you had an original ribbon cable, but a late-model drive, it could misbehave badly (e.g., pulsing; eject motor stuck on, etc.). I've observed this problem first-hand.

 

Yes, it would be equally effective to cut the traces on the drive itself, rather than playing with the ribbon cable. Personally, I prefer mucking about with easy-to-replace ribbon cable than with the drives proper.

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Yes, that is true for the internal drive if you are trying to use the MFD-51W-03 with the red cable, however, he is talking about an external drive. All external drives are properly configured to avoid this problem. There is no need to cut anything inside an external drive unless you are using it on a computer not compatible with it ... and the 512K is listed as compatible: http://docs.info.apple.com/article.html?artnum=10268

 

Pina's instructions to cut the ribbon cable (which as far as I know only appears in the Dead Mac Scrolls, page 249) refer specifically to the internal drives ONLY. The problem he's having with the external drive I suspect is ROM related and cannot be changed without altering the circuit board on the drive or re-writing the 64K ROM since this is a pre-system hardware issue that goes away when you load a system disk. Also, the red cable is designed for use with 400K drives or 800K drives that have the socket header disconnected, so all wires are connected. The original 800K drives disabled the speed control pin at the header since it was unnecessary for the them, so it doesn't matter which cable is used. The newer 800K drives did not, probably so that pin could be used for other purposes as you suggest (eg the IIGS). Whatever the reason, the yellow cable was required which disabled the those pins inside the Macintosh. If you used a red cable with the newer drives, the speed control signal is passed through and the drive goes into an endless spinning & eject cycle. Pina's instructions in Dead Mac Scrolls are greatly simplified and designed to solve your problem without explaining it, necessarily. So clipping the red cable wires with the newer drives would solve the problem, particularly since there are some newer drives with the same part number as the old (confusing indeed). But again, totally unnecessary on the external drive. Cutting those wires on the A9M0106 probably will cause it not to work properly on the IIGS, though should not affect the Mac's operation. Most likely the circuit board in the A9M0106 receives the speed signal from a Mac and disables it, whereas on a IIGS, whatever that pin is used for is applied accordingly. Pina's detailing of the problem in Repair and Upgrade (page 193) "for 64K ROM diehards" is merely informational, probably in the event you don't have the proper ribbon cable. It is very easy to confuse what Pina is saying based on his writing style so I'm not surprised JDW mis-understood.

 

I suspect that the external disk drive is queried by the system for a disk at a regular interval when attached and for whatever reason the 800K drive does not return the proper answer on a 64K ROM Mac. I'll have a look at Inside Macintosh and see if I can confirm that. FYI, the original 800K drive (M0131) also accesses the disk (though it has no LED to flash) until a disk is inserted. However, without the HD20 INIT on a 64K ROM Mac it cannot be used. This is most likely why the older drives cannot be used in the A9M0106 external enclosures, at least with the IIGS. Though if the circuit board does not receive the speed signal from the Mac, it may not know what what kind of computer it is attached to, should that make a difference. Though since JDW cut those lines, obviously it would seem to make no difference on a Mac.

 

Lastly, the 800K drives are MFD-51W, MFD-51W-10 (HD20 INIT only), MFD-51W-03 (used in the A9M0106) and MFD-51W-23 which I have seen referenced as used in the IWM Mac SEs. Obviously the last incarnation, I would love to get my hands on a MFD-51W-23 to see if they were further upgraded to avoid the problem JDW is having with the disk access. Just to be clear, I have come across drives labeled MFD-51W ONLY which appear to behave identically to the MFD-51W-03 (without the HD20 INIT), yet can use either red or yellow ribbon cable. Perhaps this is the MFD-51W-23 and Sony had dropped the suffixes at some point. Otherwise, it is a the original 800K drive which Apple subsequently crippled to prevent use without the HD20 INIT. Either way, Pina in Dead Mac Scrolls only refers to these drives as MFD-51W which I suspect is a simplification as a result of the unpredictability of part numbers and their corresponding drives. I will at some point try using the this drive in the A9M0106 to see if it operates any differently.

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First I would refer you to this if you have not read it: http://docs.info.apple.com/article.html?artnum=1605

Thank you for the link, but I believe I had posted that in the past on this site. But alas, that thread too was deleted in the server crash a few months ago! Nevertheless, I would have you know I own both types of cables (red stripe and yellow stripe). I tried those cables before and after cutting the wires I mention above. It does not solve the LED flashing issue.

 

Pina's Macintosh Repair & Upgrade book is... often unclear and contradictory to published Apple info... you really have to read it several times to understand why he's saying it. I'm afraid you mis-interpreted this to mean you had to physically cut wires on your drive.

You are correct about mistakes in Pina's books, but you are not correct in assuming I misunderstood. If you re-read my post above, you will see that I mention I had referenced sources other than Pina before making my decision to severe wires (which was done in such a way that I can easily connect them again). I tend not to trust any single source of technical information. I prefer to see the same or similar content in two or three places prior to my believing it.

 

it might be worth a look at the Apple IIGS 800K floppy controller pin-outs to see if there is a signal line that might be cut which would prevent the LED flashing and disk access.

I've cut and tried many different combinations of wires, but I the only combinations that stop the LED flashing are the same combinations that stop the drive itself from working.

 

Apple says specifically NOT to put the older drives in the A9M0106 external enclosure.

To be precise, you are referring to the second sentence of NOTE #3 at the URL you specified above. More specifically, that Apple tech page is just saying: "You should NEVER try to install the older MFD-51W or 51W-10 drive mechanisms in a PN# 661-0345 floppy drive enclosure. Only the MFD-51W-03 mechanism should be used inside a 661-0345 enclosure." Interstingly, the A9M0106 drive is not the same as the 661-0345. Nevertheless, my A9M0106 drive has the MFD-51W-03 drive mechanism inside it.

 

 

AS A HACK, you are using something that is not designed to be compatible with your system and therefore is likely to do lots of things that bothers you. I doubt cutting any cable will stop the problem without rendering the disk useless.

That is why I have not been complaining about Apple or the Macintosh in general. I merely discovered an anomaly and posted it here on this site (long ago, but all that has been wiped away in the server crash), in hopes that some other technically inclined soul, more technical and experienced than I, can possibly provide some insight that would lead me to a solution. Even if it requires some simply programming of a PIC MCU to stop the problem, I may be open to that. But I would first like to explore less involved options that may work. So far, no one has provided a solution. But that's not to say no one will. And thanks to the server crash on this site that wipe much of my experience away, the response to this problem has been "delayed."

 

I am thrilled you are helping to clarify the mis-information on the web. I am certainly not looking to take credit as discovering this, or certainly overshadow your accomplishments ... if anybody deserves the credit it's Larry Pina!

I simply try to do for others what I would want them to do to me. I also believe in the Biblical notion that "there is nothing new under the sun." No doubt, much of what we think we have invented as "new" has actually be thought of by someone else before (regardless of the fact they may have taken it to the grave with them). I therefore do not take "credit" as such, but simply mentioned my previous posts to you in an attempt to point out that I have, for quite some time, been thinking about the points you have suggested to me. But I too would like to formally credit Pina with his work. He was a very constructive and dedicated member of the Macintosh community for many years. May more such people rise up among us and keep the classic Mac community alive and kicking!

 

 

I will not state anything that I myself have not tested. That said, I must tell you that while this 800K drive works without the HD20 INIT, the actual 800K External Drive M0131, sold for the 512K & Mac Plus will NOT work.

I appreciate this insight. I've often wondered about it. But in not having an M0131 myself, I could never test such.

 

on a 64K ROM system, you CANNOT use HFS formatted anything without the HD20 INIT which will not load on a 128K. On a 512K, even with your drive, you must have the HD20 Init in order to write HFS formatted disks with a System 2.1 or later. System 2.0 and earlier will write MFS ONLY with or without the INIT.

Thank you for posting those clarifications.

 

your posts seem to indicate that you are limited to 400K without the HD20 Init. on your drive and that's how mis-information gets around.

I never mentioned any '400k limit without the INIT,' and I would take issue with insinuations that such is "mis-information." If a criticism is to be lodged against me, it would be more accurate to say that "some people could think 'such-and-such' because you did not say 'this or that.'" But I never intended my posts above to be 100% comprehensive, saying all that could be said on a given subject. Indeed, if I was able to do that, I should likely put it in print and begin sales on Amazon!

 

With that said, I appreciate your clarification on this point -- something which I was well aware of but did not clearly state in my post above.

 

 

I too look forward to new discoveries in classic Mac computing. It takes time to post those discoveries on the web, which is why we have times of relatively few posts here. But I would like to encourage those of you out there reading this to be diligent and make time to post your experiences. Posting what others have done is nice for those of us who have never read such articles or tips before. But to post your own first hand experience is far better, and it makes that information more real and more fun for yourself as well.

 

Thanks to everyone who has contributed to this thread. And a special thanks to Tom Lee for your hard work in putting together that excellent technical PDF for us!

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Apple says specifically NOT to put the older drives in the A9M0106 external enclosure.

To be precise, you are referring to the second sentence of NOTE #3 at the URL you specified above. More specifically, that Apple tech page is just saying: "You should NEVER try to install the older MFD-51W or 51W-10 drive mechanisms in a PN# 661-0345 floppy drive enclosure. Only the MFD-51W-03 mechanism should be used inside a 661-0345 enclosure." Interstingly, the A9M0106 drive is not the same as the 661-0345. Nevertheless, my A9M0106 drive has the MFD-51W-03 drive mechanism inside it.

 

Actually no, at the risk of calling another misunderstanding, that's not what the note says. Part #661-0345 is NOT a "floppy drive enclosure". It is in fact the drive mechanism inside the A9M0106 enclosure. MFD-51W-03 is the SONY part number and 661-0345 is the Apple part number for the sony drive mechanism. A9M0106 is the Macro part number for the entire assembled unit marketed as the 'Apple 3.5" Drive' which contains 661-0345, the Sony drive mechanism. So what you say below is actually correct but misleading. The A9M0106 is in fact NOT the same as the 661-0345. However, 661-0345 is the same as the MFD-51W-03 and is not an "enclosure" of any kind but a drive mechanism. So, what the note actually says in translation is: don't use Sony drives with part number MFD-51W or 51W-10, otherwise known as Apple part number 661-0305, inside the external drive with Apple part number A9M0106, otherwise known as the Apple 3.5" Drive, but ONLY use the Sony drive with part number MFD-51W-03, otherwise known as Apple part number 661-0345. Sorry for the elaborate explanation, but as I said before this is how misinformation gets started, through no fault of our own. Apple's site is the source of much misinformation itself, but in this case I have personally verified what they are saying, if however badly. So it makes perfect sense that your A9M0106 contains the MFD-51W-03 – it's supposed too!

 

You are correct about mistakes in Pina's books, but you are not correct in assuming I misunderstood. If you re-read my post above, you will see that I mention I had referenced sources other than Pina before making my decision to severe wires (which was done in such a way that I can easily connect them again). I tend not to trust any single source of technical information. I prefer to see the same or similar content in two or three places prior to my believing it.

 

Not to beat a dead horse ... but what other sources detail cutting the ribbon cable on an external drive to disable the speed control & voltage? Are you referring to Lee's article you linked to above? That also speaks solely of the internal cables, not external. In either case, the writing is ambiguous and could easily be mistaken to mean any drive connected via any method. While I have certainly not seen every source on the subject, those are the only three texts in which I have seen this problem explained and I have never seen a source that explicitly indicated the cutting of an external drive's wiring was necessary. Also, did you try to use the red & yellow ribbon cables inside the A9M0106, or on your internal drive? Out of curiosity what is the Sony part number for your internal 800K drive, is it also a 51W-03?

 

Also, please forgive me, I did not mean to insinuate you had intentionally provided misinformation at any time. Moreover, that lack of complete information is how misinformation originates. And certainly we are all guilty of it (including Pina and Lee)!

 

Cheers :beige:

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your posts seem to indicate that you are limited to 400K without the HD20 Init on your drive...

Mac128, you've inspired me to be even more zealous about confirming things 100%. Tonight I did some checking, and it would appear that you are indeed "limited to 400k without the HD20 INIT." At least, you are if your 800k disk is formatted HFS. And despite what I've "read" on the net, I cannot get any of my 800k disks to format as MFS. You can read my report about formatting 400k & 800k disks in HFS/MFS.

 

My "guess" is that you would not be limited to 400k without the HD20 INIT if you could format an 800k disk MFS. The reason my Mac512 with 64k ROMs cannot see 800k disks without the HD20 INIT is because of the HFS formatting, I believe, not the physical size of the disk itself. But again, I need to create an MFS 800k disk to test this for sure. So if you have some insights to share in this regard, I'm all ears!

 

Thanks.

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JDW and Mac128 -- thanks for providing such an incredibly detailed discussion about this issue. With your permission, I'd like to include a summary of your conclusions (with proper attribution, of course) in a future rev of the classic mac tech docs.

 

I continue to be amazed at the knowledge (and persistence) of the folks on this forum!

 

--Cheers,

Tom

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Tom, I'm not one for taking credit. But if some of the dialog I've contributed on this site can assist you in bettering the classic Mac community, then I'm all for it. Please freely use whatever information I've posted as you see fit.

 

And once again, Tom, thank YOU for that outstanding technical document. A lot more work went into that than we've posted here, that's for certain. You are to be greatly commended for that excellent work! Your work actually inspired me to be more diligent about testing things on my old Macs and toying with hardware modifications. For that I am sincerely grateful to you.

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