Why Not the DIsk /// ?

And since when has Apple ever made "compatibility" hardware for current products in the wild?  

What do you mean?

Apple were very good about compatibility in the 80s-90s. In fact, LTS for their products was financially crippling them, as they were fabbing short runs of parts for machines decades old to satisfy AppleCare on those products until 1996/7.

As an aside, I wonder what pure SOS would look like on a IIe...

As would I. it needs a memory remodel as the //e does not have the same memory map, but I suspect that it could be done, if not for the //e, then at least for the //gs, but it would take someone more spry than I am to do it. I would love to see SOS for the //e with EXP RAM or the //gs. It was one of the best OSes ever made!  If someone wouod ever port SOS to an expanded //e and add A2D on top of it, it would be an incredible 8b OS. 

I dont know but I have two very early Disk III units which are almost identical to a Disk II. To be honest, a card to utilize the Disk III would have been smart. It was pretty spaceage in styling compared to the Disk II. I like it better in design than the Unidisk 5.25" drive in contstruction anyway.

I wholeheartedly agree, and they spent the money to design the DuoDisk, and UniDisk. I see no reason why they could not have taken the Disk /// design model and made it work on the ][ series, other than that they just did not think to do it. I occasionally use Disk ///s on my ][ machines just because I prefer them aesthetically next to a ProFile. 

As an anecdote, our original Disk /// looked identical to the Disk ][ and had a typewritten sticker on it that said 'Apple /// Disk Drive'. This is what they supplied with the /// developer system when it first came out. They shipped these, with more professional stickers (they still said Disk ][, but the drive label said 'Disk ///. Drive 2' or similar, instead of just 'Drive 2', for the first 6 to 10 months, ere they released the final Disk ///. We had two external drives on the office ///. The first was the modded Disk ][, the second an official Disk /// marked 'Drive 3' along with a 10MB ProFile. It always bothered me that we did not have a D4 and that the stack was un-even and non-uniform. 

IDR if the twpewritten sticker was from Apple or if someone in the office put it on the drive so that we did not forget what it was, as from the front, it was not distinguishable from any other Disk ][. I recently saw one of those early drives on fleebay. I am more inclined to buy a dead Disk /// and to convert it to a Disk ][ for its aesthetics so that i can eventually have three to stack on top of a ProFile and under a Monitor ///. ;)

I’m guessing that there weren’t enough drives around to make it worthwhile. With the costs of paying someone to design and test the card and then the production and associated costs it’s probably not worth it.

Another issue is that I suspect most Apple II stores wouldn’t want to carry it. They already stock the Disk II. Unless the Disk III was significantly cheaper there’s not much incentive to stock it. Even then, with a limited supply you’ll run out quickly and a month later you’ll have someone coming in looking for a second drive that you can't get.

I'm thinking it was a combination of two factors:

1. The cost to develop and manufacture a controller card was too high to justify vs the potential profit of selling it and the Disk IIIs. (While we enjoy easy, computer-based circuit design and downright cheap PCB manufacturing costs today, that was certainly not the case in the early 80s.)

2. If Apple couldn't sell the Apple III systems and drives, it could scrap them and get a tax write-off. (Remember the Lisa?) This was probably also more advantageous than the potential profit (and taxes paid) from selling the drives to IIe owners.

I am going to knock this one down. They did not bury the Disk /// units, they made millions of them, and they did not bury the remaining stock of Apple ///s as they did with LISA systems. They could have sold them to //e clients and made more than any tax writeoff was worth with one TTL card that has PROMs that comprehend device select, and have gone that route. Likewise, they did not crush out ProFile drives and they even made the stand for the ProFile and Monitor ///, so you could have stacked a ProFile, a Monitor /// and three Disk ///s on that stand. 

There is no reason why a vendour would not sell a Disk /// card for the Apple //e. They sold the DuoDisk card, and the real issue is why they designed the DuoDisk instead of selling the Disk /// for the //e. That was yet-another-product for any vendour to carry and support, and to be frank, the Disk /// was a smarter design. 

If they had pushed the Disk ///, possibly rebranded, for the ..e, then there would be no supply issue, and the later DuoDisk and UniDisk could hav e used the analogue board from the Disk ///, and still worked, and supported four devices off one card. 

The cost to develop the card also,l was naught. They already had the design. It was built into the /// mainboard, and all they needed to do was adapt it to the ][ series bus, and be done. They had the components, and to spare. In fact, they had the Disk /// components and Apple /// components as spares until at least 1992, when i last had to order any. 

My case in general, is that the /// and //e teams were simply too separate, and did not cooperate enough to think about this as a solution. I would love to see a Disk /// card for the ][ series. If I live long enough, I might make one. AFAIR, it is a Disk ][ interface with some extra data lines that told the analogue board if it should accept the signals or pass them on to the next device. There was no magic involved: If the analogue board received a D3 signal, and it was D1, it passed all signals to the next device, and then D2 passed it to D3. If it was the correct device, it used the signals. 

It was truly intelligent design, and smarter than MFM by a long way. 

Dr. Webster wrote:

Timelord wrote:

I am going to knock this one down. They did not bury the Disk /// units, they made millions of them, and they did not bury the remaining stock of Apple ///s as they did with LISA systems. They could have sold them to //e clients and made more than any tax writeoff was worth with one TTL card that has PROMs that comprehend device select, and have gone

Oh dear me, my apologies. I was not attacking you either personally or professionally. I was simply saying that in my mind, the idea that they would write off inventory was not a particularly valid argument for this hypothetical, as if they wanted to write off the /// series, they would have done it, and not greenlit the ///+, &c.

 I am not an angry, or particularly emotional person; and I would never intentionally antagonise anyone else. 

I did use the word millions, but that was meant in the proverbial, like the Arabic 'forty'.

I do not know the actual total. I know that it was at least 200,000 drive units, double that if you count the number of /// and ///+ systems to count their internal drive, but that is another thing entirely. I have seen Apple /// serials above 120K, and when you consider that these are ///, and do not include ///+. the total number of /// series machines is likely somewhere between 200K and 250K. That is my estimate, based on observations over the years, but unless Apple release some factual total of units produced, we will likely never know. 

Companies love to celebrate their successful systems, and hide their failures. 

Apple however, absolutely did expect every Apple /// owner to buy at least one Disk ///.

Here is the basic business logic behind that:

Many business programmes for the Apple /// either outright required two drives, or would require a lot of disk swapping if you did not have at least two drives. In the 1980s, most people who worked for a company, using a system like the Apple /// made at least £8 (at the time, say, US$12) per hour. If the average person wasted just twenty minutes per day swapping disks, then after three  days they waste one full pay hour of time. If you scale that up to what was a general salary for technical work in the era, after a few months, that second drive has paid for itself, and has created a net gain for the employer. 

Our /// system had all four drives in use, and a ProFile. Note that the /// never supported more than four total Disk ///s, in any way that I know about. The ///+ changed the ribbon to a DB, but the interface remained unchanged, so, still total 4 drives. If you know of some way to hae twelve drives on a /// system, I would love to know how. Not that I would ever need that many, but AFAIK there was never a separate Disk /// controller card, for the /// series, to add up to four more drives. I may simply not know about it. 

Anyway, the bottom line, is that there is at least one external Disk /// manufactured per /// and //+ system made; likely more, as they were built with mostly already off the shelf parts. The first run were all in Disk ][ cases, and had a Disk /// sticker applies tot heir upper-left cornet. The only different component between the Disk ][ and Disk /// is the analogue board in the drive, and it was precidely this that allowed signal passthrough and drive select. 

I suppose, a better question to ask, is why this particular technology was not used for the DuoDisk or other later innovations. I recall nothing about the Disk /// analogue board that was unreliable. I can certainly understand that if Shugart mechs were at some point more costly than making an in-house drive (huzzah FileWare drive!), that Apple would use their in-house design, but in all cases, they used their own I/O boards, so why not use the Apple /// Drive Select with four devices per controller?