Are newer PATA drives backward compatible with older PATA interfaces?

I'm going to be upgrading the hard drive on an old-model Mac, but before I make a purchase, I want to research my options. At this point, I know for certain that the computer's drive interface is ATA-2 and that I will need to buy a drive that has a PATA, not SATA, interface. What I'm not certain about is whether or a modern drive would be sufficiently compatible with such an old interface.

I do have a background in both electronics and programming, so I could do detailed research about the differences between ATA standards, but I thought I would see if anyone out there has enough (accurate) knowledge to address my questions, thereby allowing me to avoid engaging in more in-depth research.

So here are my questions:

Are all PATA standards backward compatible?
In other words, if I buy a drive that complies with an ATA-4, -5, -6, -7, or -8 standard can I plug it into an ATA-2 interface and expect the drive to function?
If there are any incompatibilities among the different generations of ATA standards, are they merely speed-limiting issues or are there differences in the functionality of the pins that might cause permanent damage to the drive or the computer?
For that matter, since drives tend to be sold independently of computer systems, are there any PATA variations that I should watch out for (that might have manufacturer-specific pin configurations)?
I've noticed that some sellers are listing drives with the tag “PATA II”. Does anyone know exactly what the “II” refers to? Does that mean it's ATA-2 compliant, or is it some other marketing designation that some manufacturer concocted?

It would save a lot of time and typing if you just stated what old-model Mac model you're talking about and what OS and version it's running. It can make quite a difference as to what HDD is used that will work properly.

That would be true if and only if I wanted knowledge about a specific computer. That's not what I want. I want general knowledge that can be applied to any computer.

I can enter any Mac model into a goggle search engine and find web site databases and forum posts that provide cursory information about the specifications of old Mac computers. It does me little good to know that such-and-such computer used a 2.5" IDE drive. I want more in-depth information.

In fact, Apple provided developer notes on their models that are much more detailed. It includes hardware and software specifications. This is the portion that applies to my old Mac computer model:

The implementation of the ATA interface on the Macintosh … computer is a subset of the ATA / IDE specification, ANSI proposal X3T10/0948D, Revision 2K (ATA-2).

What that doesn't tell me is whether or not drives that conform to an ATA-3, ATA-4, ATA-5, ATA-6, ATA-7 or ATA-8 specification are compatible, and (if not) why.

If it is the case that drive selection is dependent upon the OS, then I want a separate answer for every version of the Mac OS from 7.5 to 9.1. (I develop software for vintage computers as a personal hobby, and I tend to create partitions for each version of the OS so I can run old software under a variety of conditions. Therefore, any old Mac I get will have to perform under the widest possible range of OS's that it can support.)


One of the problems with asking for "advice" is that the people responding may or may not know what they are talking about, and may or may not provide accurate information. If someone can explain the technical reasons why I should focus on particular ATA specifications then I am not only more likely to trust their knowledge, I am empowered to make my own educated decisions.

If all I do is list my hardware and OS and wait for someone to give me list of compatible drives from some unknown source, then I'm taking an unnecessary risk and I haven't learned anything in the process.

One of the problems with asking for "advice" is that the people responding may or may not know what they are talking about, and may or may not provide accurate information. If someone can explain the technical reasons why I should focus on particular ATA specifications then I am not only more likely to trust their knowledge, I am empowered to make my own educated decisions.

If all I do is list my hardware and OS and wait for someone to give me list of compatible drives from some unknown source, then I'm taking an unnecessary risk and I haven't learned anything in the process.

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That's not how forums work. You post a question and gather up the answers when replies are given. It's up to you to decide what's useful or not. You're asking for highly technical information. Also the title of your thread is very generic: "Are newer PATA drives backward compatible with older PATA interfaces?"

You also stated this:

I'm going to be upgrading the hard drive on an old-model Mac, but before I make a purchase, I want to research my options. At this point, I know for certain that the computer's drive interface is ATA-2 and that I will need to buy a drive that has a PATA, not SATA, interface. What I'm not certain about is whether or a modern drive would be sufficiently compatible with such an old interface.

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Member "pm-r" was trying to narrow that down in order to provide an answer.

Let's say for discussions sake that we were talking about desktop Macs. The last desktop iMacs that used 3.5" PATA/IDE drives were the iMac G4 line from 2004.

So if we were to say...would a 3.5" PATA/IDE drive from a 2004 iMac G4 work in 1998 G3 iMac?...not sure I haven't tried it. I'm pretty sure they have the same data cable and power cable connectors...so no problem there.

I guess this could be the basis of a discussion or experimentation.

- Nick

My first expectation of posting this question on a forum is to possibly make contact with someone who has prior professional experience in the computer engineering field, someone who enough knowledge of the now-obsolete PATA interface that they can provide some insight or trade article references that highlight backward compatibility issues, both at the hardware and software level. If no one with that caliber of technical knowledge ever posts on public forums than I'm wasting my time.

If there are people on this forum with that kind of technical knowledge, I want as much good information as I can get so I can look at a manufacturer's data sheet for a drive and determine from the ATA specification if I should include or exclude it from consideration.

While the question I placed in the subject line of my post may be broad, it seems to me to be a perfectly valid and useful question. Why wouldn't consumers want a useful method by which they can filter their purchasing choices?


If it turns out that computer engineers don't use this forum, then there's still the possibility that anecdotal information from computer users may be useful. They could respond by saying "I put such-and-such drive in such-and-such computer and it worked fine".

However, if broad-topic discussions aren't allowed on this forum then I'm (once again) wasting my time.


If the moderator needs a question from me that is narrower in scope, then how about this:

Will a drive that conforms to the ATA-8 specification function with a computer that conforms to the ATA-2 specification, in theory and/or in practice?

This question is independent of computer models and operating systems and drive manufacturers. If a forum user doesn't know what an ATA specification is then that user is welcome to ignore my post. That is how forums work, isn't it?

To be honest #1: Reading your posts...you sound quite knowledgeable. In fact...with the knowledge that you seem to be displaying...I'm kind of surprised you cannot answer this question yourself!

To be honest #2: Also from reading your posts...I honestly think that you are over-complicating things. Have you ever heard of "analysis-paralysis"?

To be honest #3: Just do it! Buy whatever PATA drive you are thinking of getting (I hope not a new drive...just something used/cheap)...and stick it in the Mac you are working with. If it works it works...and if it doesn't it doesn't. At least you have an answer. You can also use the current drive as a reference as to what to buy.

Folks stopped using PATA drives 10 years ago. Memories get rusty...and folks that worked with PATA drives day to day back then...probably didn't go into this much detail about them!

Just do it...and don't turn things into a PhD dissertation!

- Nick

p.s. Reading your posts...you do seem to appreciate a high level of detail. Give this a read (link below)...and maybe it will contain the answer you are looking for. If the answer is not contained in this article...then it's probably not an important compatibility parameter:

http://en.wikipedia.org/wiki/Parallel_ATA

I have performed numerous upgrades on older Macs in the past, and I rarely have problems with installing new drives. However, there is a 2 decade gap between ATA-2 and ATA-8 and the article you mentioned doesn't address the issue of backward compatibility, primarily because putting new hardware in old machines is relegated to small number of hobbyists, not the mainstream for-profit personal computer market.

There were a couple or so times that I didn't entirely think through my creative modifications and I ended up damaging circuits boards, so I've learned to employ some caution before recklessly plugging things together.

The other big concern for me is cost. I would prefer to install an SSD drive, and there are actually some IDE/PATA SSD drives available. (Sadly, there are no SCSI SSD drives.) However, SSD drives aren't cheap. I not only don't want to damage the drive (or the computer), but I don't want to buy a drive that I may not be able to use if it isn't compatible.

My goal here isn't to over-analyze. My goal is to find some evidence either for or against the practice of plugging a 2014-vintage drive into a 1995-ish-vintage computer. I was never worried about upgrading any drive in a Mac that is G3 or later, and the old SCSI stuff is hearty stock, once you learn how to configure it properly. It's the models that are in gray-area transition from 68K to PPC, where Apple started to use (P)ATA for its drives, that give me pause. The ATA-2 standard was very new 2 decades ago and I don't know if it radically changed over the next decade, or if the revised standards are just subtle improvements.

It's possible there may not be anyone around (online) that is an expert in the old PATA interface. They may all be busy enjoying their retirement years. I wouldn't mind doing that myself, once I can afford it.

LivingInThePast said:

However, there is a 2 decade gap between ATA-2 and ATA-8 and the article you mentioned doesn't address the issue of backward compatibility, primarily because putting new hardware in old machines is relegated to small number of hobbyists, not the mainstream for-profit personal computer market.

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Two decade gap?...20 years?...1994? I'm a bit confused...are we talking Apple Macintosh computers?

- Apple used 3.5" SATA drives from about 2004-2011 (then switched to 2.5" in some desktop models)
- Apple used 3.5" PATA drives from about 1998-2004
- Apple used 3.5" SCSI drives from about 1987-1998

Where does the 20 year gap between ATA-2 and ATA-8 come in...in relation to Apple computers?

LivingInThePast said:

My goal is to find some evidence either for or against the practice of plugging a 2014-vintage drive into a 1995-ish-vintage computer.

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I think that stating your goal was a VERY good idea. I think that this is the sort of info other folks responding in this thread earlier were looking for.

With that said:

- What sort of "2014-vintage" drive are you talking about (maybe provide a link)?
- What "1995ish" computer are you talking about?

Thanks,

- Nick

p.s. Apple of course also used 2.5" drives in notebooks, Mac-Mini's, early MacBook Air's, etc. But I was focusing on desktops due to the old nature of this 1995ish computer.

LivingInThePast said:

The other big concern for me is cost. I would prefer to install an SSD drive, and there are actually some IDE/PATA SSD drives available. (Sadly, there are no SCSI SSD drives.) However, SSD drives aren't cheap. I not only don't want to damage the drive (or the computer), but I don't want to buy a drive that I may not be able to use if it isn't compatible.

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It was news to me that there are PATA SSD drives available. But a quick Web search shows that you are correct about this. I'm a bit surprised by this, because you wouldn't think that the market would be large enough to justify developing a PATA version of an SSD.

I haven't heard from anybody, or of anyone, who has installed a PATA SSD in a Macintosh.

But I agree with those who have said that you are making this too complex and difficult. If I were in your position, I'd choose two or three likely products that might seem to be perfect for the job, and then contact the developer(s) of those products. I'd ask if those products were appropriate for the purpose to which you want to put them to, and maybe even if they would recommend a retailer that would refund your money if the product didn't work.

Let me put on my attorney hat for a second. (I am an attorney, btw.) If the developer or retailer tells you that their product would work for you in your model of Mac, that creates what is known in the law as an "implied warranty for a particular purpose." That's a legally enforceable warranty. So, if you are looking for a reliable assurance that a particular SSD will work in your Mac, that's how you get one.

I note that Other World Computing sells SSD's specifically for old Macs with PATA:
Mercury Pro Legacy 3.5" IDE/ATA SSD Internal Drive Kit for IDE/ATA desktops, SSD Serial ATA 2.5" Solid State Drives using High Performance SandForce Processor solution
These folks are Macintosh experts. It's a safe bet that they have lots of experience in this area and that they can help you with what you need.

Please let us know how things work out.

1. The newer ATA standards primarily introduced faster transfer speeds... There were also required changes in the LBA addressing as the size of drives became larger.

2. The purchase of an ATA/IDE device - I would say is probably going to work with any ATA/IDE interface. I am sure there are cases where they won't work - at all - and in some cases you may need to find 3rd party drivers to enable the device to work with the interface.

3. The limitations related to whether a drive is usable at all and how much of the space on the drive is usable were often set by: 1) motherboard manufacturers and b) operating systems from those making both of them that set artificial size limitations not foreseeing the possibility of anything larger. Some of these can be overcome by new drivers that have been put out.

Due to this item, there is no correct answer to your question without knowing what motherboard and which operating system you want to put the drive to use with and then finding someone that is knowledgeable related to the motherboard, operating system and the drive you want to use.

4. WD was the last manufacturer of PATA drives - they quit making them last year. Any PATA drive you find from a parts seller at this point are those still left on the shelf or specialty drives - such as the one Randy linked to above from OWC.

To do what you want, I would call OWC and ask them.
For more detailed info, a decent place to start your reading is the wiki and the sections on X86 size limitations and interface limitations. For someone only looking for - will 'x' drive work with 'y' motherboard and 'z' operating system, you still may not find an answer unless you are lucky enough to find someone that has tried the specific drive, motherboard and OS you intend using.

To keep this short and simple and a suggestion for the OP, and it may not have all the technical jargon he is looking for, but you'll find a LOT of useful info here, and it has been a valuable site for may Mac users over the years doing upgrades etc.:
Apple/Mac/OS X News, Tips and Tech Articles - xlr8yourmac.com

But I will add at least two rather major details as I discovered last year when looking into replacing the hard drive in an old iBook:
- not all Macs can support Big Drives, and
- there are not many new/unused IDE ATA PATA drives that are even available for sale.

The last makes a lot of the tech logical knowledge almost useless. i.e: you know what you want or need, but just can't purchase it.

But still lots of choices if one doesn't mind using used stuff.

PS: I was quite surprised to find that some serious enterprise places still use and rely on SCSI drives, but not the old Apple parallel connector type ones.

excuse me i can answer this.

i take it your upgrading a laptop correct?? the reason i ask this is most older power pc macintosh's are not pata pata is the standard for laptop hard drives ide is the standard for the mac g3 g4 g5 and so on so my question i need a answer from you is simple...

what model of macintosh certain macintosh computers won't go over a certain megabyte size because there EFI firmware won't allow them to for example a macintosh powerpc g4 cube will only read 120 gig hard drive as the max hard drive size nothing larger will work older macintoshes like the g3 and g4 ibooks and g3 lambard edition won't read anything larger then 120 gigs unless you firmware update them to accept the larger drive size this is why i need to know.

the good side great you are resurrecting a old mac bad side is if your o.s is tiger you might want to think about a new mac instead

as for specifications it doesn't matter on pata because pata cane downclock and upclock at any speed its not like sata

Alrighty then! Now the discussion is really heating up. Thank y'all for the feedback and useful advice.

The reason I didn't launch directly into providing specific hardware and OS stats is that I'm back into my collecting mode and I'm shopping around for several models of old Macs. Prior to actually purchasing a new set of toys, I'm collecting information about which upgrades I should choose and where I can find the best prices and most trustworthy sellers. Until I encounter a specific problem with a specific computer, I can't provide specific information. I'll be buying a wide range of computers and using a wide range of OS's with each of them.

Having said that, I've already discovered that Apple started using IDE/ATA interfaces in their 5300/1400/2400/3400 PowerBooks as early as 1995. 2014-1995=19, which is nearly 20 years, if you round up.

I always appreciate getting (free) advice from an attorney. Computer shoppers are deluged with a virtual sea of unscrupulous sellers, so it's always nice to know what protections I may have. I've been very impressed with OWC's product line, even though I usually end up buying Samsung SSDs. OWC doesn't make SSDs for pre-G3 Macs, so I will put my questions to them to see if they can offer a highly technical answer as to why that is the case. The information they provide will be useful for making a similar selection of a traditional hard drive.

The drive-size-limitation problem is actually pretty easy to work around. All one has to do is create smaller partitions. I always create a boot partition that is formatted and sized to match the type of hard drive that would have been originally installed on the computer.


As a side note, I've spent half of my adult life in college studying math and engineering and science, and I've worked in the electronic component industry. I've spent my life applying scientific and technical knowledge to the selection of board-level electronic components. Taking this same approach to consumer electronic component selection is second nature to me.

Throughout my life, both as a student and as a working professional, I've been bombarded with this exact same reaction: why don't I just accept the information I'm given, put out the least amount of effort, collect my paycheck, keep my mouth shut, and stop asking questions? People can't seem to understand why I 'overcomplicate' everything. At the same time, I can't understand why other people seem to 'under-complicate' everything.

I guess the answer to that lies in my own nature, as well as in the definition of 'civilization'. For myself, I know that I've always been driven to understand how and why things (engineering and natural systems) work. Through reading and life experience, I've observed that our technology-driven civilization is the result of two human desires: 1) the desire to acquire 'good' information (what we call knowledge) so we can have some control over the natural world and create technology; and 2) the desire to do and create things that have never been done or created before.

Neither of these desires are compatible with uncomplicated thinking or living. Understanding anything to a greater depth necessitates an examination of systemic interactions, and that endeavor is mired in complexity. That's why it takes so many years for students to learn a specialization in college.

Exploration and creation are also not activities that are inherently uncomplicated. If a lack of complication was our foremost desire, we wouldn't climb mountains, build space shuttles, or compose symphonies. All of the really worthwhile pursuits in life are complicated. Those pursuits take enormous effort, they expose us to uncertainty, and they create a need for useful information.

Whenever I encounter someone that wants to know how or why somethings works, I applaud their curiosity. I think if humanity has a genuine desire to be smarter, then there's hope for us all.

LivingInThePast said:

The reason I didn't launch directly into providing specific hardware and OS stats is that I'm back into my collecting mode and I'm shopping around for several models of old Macs. Prior to actually purchasing a new set of toys, I'm collecting information about which upgrades I should choose and where I can find the best prices and most trustworthy sellers. Until I encounter a specific problem with a specific computer, I can't provide specific information. I'll be buying a wide range of computers and using a wide range of OS's with each of them.

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Sorry man…but you're even making the collecting of old Mac's over-complicated. Unless you have deep-pockets…the collecting of older Mac's is a exercise in opportunity/coincidence/luck.

Collecting old Mac's isn't about writing a BIG check by buying whatever you want via eBay. It's about getting lucky/fortunate via Craig's List, thrift stores, garage/yard sale's, business's getting rid of old stuff, stuff found on the curb, or dumpster's.

In these cases you have a specific computer to focus on…which may or may not have specific operational issues. With what you mentioned above…you're preparing for contingencies that may or may not ever surface.

Obtain a specific computer…with a specific issue (which may not even be hard drive related)…then research & fix the problem.

LivingInThePast said:

Having said that, I've already discovered that Apple started using IDE/ATA interfaces in their 5300/1400/2400/3400 PowerBooks as early as 1995. 2014-1995=19, which is nearly 20 years, if you round up.

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Great. From a casual conversation regarding computer history…this is all well and good. Now purchase an older Apple laptop (5300/1400/2400/3400) with a hard drive problem..and fix it.

Without any of these computers in your possession (without a specific issue to fix)…you're just blowing a lot of hot air! What if…what if…what if!!!

Get an old computer with a specific problem…now you're not saying "What if…"…your saying "How can I fix this?"

LivingInThePast said:

As a side note, I've spent half of my adult life in college studying math and engineering and science, and I've worked in the electronic component industry. I've spent my life applying scientific and technical knowledge to the selection of board-level electronic components. Taking this same approach to consumer electronic component selection is second nature to me.

Throughout my life, both as a student and as a working professional, I've been bombarded with this exact same reaction: why don't I just accept the information I'm given, put out the least amount of effort, collect my paycheck, keep my mouth shut, and stop asking questions? People can't seem to understand why I 'overcomplicate' everything. At the same time, I can't understand why other people seem to 'under-complicate' everything.

I guess the answer to that lies in my own nature, as well as in the definition of 'civilization'. For myself, I know that I've always been driven to understand how and why things (engineering and natural systems) work. Through reading and life experience, I've observed that our technology-driven civilization is the result of two human desires: 1) the desire to acquire 'good' information (what we call knowledge) so we can have some control over the natural world and create technology; and 2) the desire to do and create things that have never been done or created before.

Neither of these desires are compatible with uncomplicated thinking or living. Understanding anything to a greater depth necessitates an examination of systemic interactions, and that endeavor is mired in complexity. That's why it takes so many years for students to learn a specialization in college.

Exploration and creation are also not activities that are inherently uncomplicated. If a lack of complication was our foremost desire, we wouldn't climb mountains, build space shuttles, or compose symphonies. All of the really worthwhile pursuits in life are complicated. Those pursuits take enormous effort, they expose us to uncertainty, and they create a need for useful information.

Whenever I encounter someone that wants to know how or why somethings works, I applaud their curiosity. I think if humanity has a genuine desire to be smarter, then there's hope for us all.

Click to expand...

Now you're just going off on a tangent. Your personal philosophy on creativity or problem solving is fine…if you want to turn this into a purely intellectual only conversation. Which is basically what you are doing at the moment…since you don't have a specific computer with a specific problem to repair.

Like I mentioned above…you're trying to prepare for problems that don't even exist at the moment. You haven't purchased a specific computer with a specific problem to solve. And this is why you're making things overly complex in this thread!

- Nick

p.s. By the way. I've been using & collecting Mac's for 28 years…and I own more old Mac's than you can shake a stick at (I'm not talking "little numbers" like 10-20 old Mac's). I know what I'm talking about…you're making things too complicated!!!

Say Nick, do you have any photos or links to photos of your Mac collection...??? It sounds quite interesting.

Sorry to go OT.

pm-r said:

Say Nick, do you have any photos or links to photos of your Mac collection...??? It sounds quite interesting.

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OMG...I'm not that organized...but would like to be! I need a larger room (just a smaller room in the basement). I've tried going vertical by building shelving...and even that's not working.

Bought another used Mac on Monday...so the collection continues to grow!

- Nick

Were you the mysterious buyer of this Mac collection a few years ago??? Hmmm...???

Mac Museum Sells for $10,000 on eBay | Cult of Mac

And it seems the interest in old Macs is growing in Japan lately:
Tokyo's hidden museum of Apple Macs - Telegraph

But maybe another one or two for your collection...???

pm-r said:

Were you the mysterious buyer of this Mac collection a few years ago??? Hmmm...???

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Not me! I actually (within the last 6 months or so)…saw a person in South or Central America was selling a $40,000 Apple/Mac collection. Quite a lot of stuff! Needless to say…I din't place any bids!

I just looked…thinking that it might still be there…but couldn't find it.

- Nick

LivingInThePast said:

The drive-size-limitation problem is actually pretty easy to work around. All one has to do is create smaller partitions. I always create a boot partition that is formatted and sized to match the type of hard drive that would have been originally installed on the computer.

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It's a common myth that doing that will work.

Older Mac's ROM's only support 32-bit LBA (Logical Block Addressing), and support of greater than 128 GB for internal hard drives requires 48-bit LBA and OS X 10.2 or later.
Macintosh: Using 128 GB or Larger ATA Hard Drives
How Big a Hard Drive Can I Put in My PowerPC Mac? | Low End Mac

Mirrored drive doors G4's and later (and 2002 QuickSilvers too) can do 48-bit logical block addressing. Earlier Macs cannot.
The 2001 QuickSilver still had the 128 GB drive limit. The 2002 QuickSilver was produced from January to Aug. 2002 when it was replaced by the MDD that had 4 RAM slots instead of earlier 3.

There are three ways you can access the full capacity of an internal drive over 128GB if your model of Mac doesn't natively support 48-bit LBA.

1)You can use a third-party (non-Apple) software driver
or
2)You can install a PCI card to give you a 48-bit internal IDE bus (obviously this is only an option for Macs that have PCI slots)
or
3)You could put your drive into a FireWire hard drive case kit (assuming that the kit uses a recent FireWire to IDE bridge chip.)

Note that partitioning your hard drive *will not* allow you to access more than a total of 128GB. *That is a common myth.

You can format a hard drive larger than 128GB on a different computer that can do 48-bit LBA, or in an external FireWire case, into multiple partitions. *And, indeed, when you install the drive back into the original Mac that can't do*48-bit LBA, some users have found that their Mac may recognize more than 128GB. *However, there will be*read/write errors actually trying to access anything above the 128GB limit. The OS may report the higher capacity, but in reality you will not be able to *use* more than 128GB.

Intech's ATA Hi-Cap Support Driver software ($25) allows the use of extended capacity ATA drives (drives greater than 128 Gigabytes in size) on older (Pre-Mirrored Door) G4 and some G3 Macintoshes running MacOS X versions 10.2 and later.
Intech Software Corporation : SpeedTools ATA Hi-Capacity Driver

OWC used to include the ATA Hi-Cap Support Driver for only $15 if you purchases a drive from them (this is the old link for that, it no longer works):
Other World Computing - SPEEDHCCD Item Not Found