Tag Archives: Peripherals

A Look at On Three’s 512K Memory Board for the Apple III

When Apple introduced the Apple III at the National Computer Conference in May of 1980 in Anaheim, California, it was touted as supporting up to 512K of RAM (as opposed to the Apple II and II Plus, which commonly shipped with up to 64K).  Thus, I was somewhat surprised when I opened this Apple III and took a look at the installed On Three 512K memory board.

On Three's 512K Board

On Three's 512K Board

I don’t know specifically what I was expecting – probably a similar set up to what you see in Apple IIIs with 128K and 256K boards.  And that’s sort of what I got, with the exceptions of the additional wires and cables coming from the memory board and attaching to various spots on the motherboard.  The person from whom I acquired the Apple III didn’t have any documentation about On Three’s expansion, so I was confused.  Why would a 512K board need such additional electronics if the III natively supported that much memory?

On Three's board includes several modifications

One of the unfortunate side effects of the III’s short lifespan is that Apple never developed more than a handful of expansion cards for the machine.  While cards such as the ProFile controller and the UPIC were produced in fairly plentiful numbers and are easy to find today, Apple never got around to releasing memory boards with more than 256K RAM, or much of anything else for that matter.  This left it up to small third party developers to manufacture and support peripherals for the die hard users who refused to migrate to Macintosh or other Apple products.

One of these developers, a user group called On Three, holds a special place in Apple III history.  While most UGs of the day held weekly or monthly meetings and offered other services such as shareware sales and newsletters to members, On Three took it much further.  In addition to printing a professional monthly Apple III-specific magazine, they also published numerous commercial-quality software titles and the 512K memory expansion.   The latter is doubly impressive, as Apple never released much in the way of low-level technical documentation for the machine, so it represents an excellent hardware hack in the truest sense of the word.

Back to the issue at hand.  I had this neat add-on, and no documentation for it.  Fortunately for me, when Dave Ottalini decided it was time to get rid of his Apple III collection, it ended up in the hands of Bill Degnan.  Degnan photographed and commented on much of the collection, including the 512K board.  It was his website that turned up in the Googles when I was hunting for more information.  After a brief email exchange, Bill provided me a copy of the scan he made of the user’s guide.  (You can get a copy here, if you’re interested.)

A quick perusal of the PDF gave me the answer to my question:  the Apple III doesn’t actually support 512K.  SOS does but not the hardware itself, at least not without some modifications.  The manual doesn’t really go into much other technical detail, but there it is.  In the mean time, enjoy some pictures of the board while my search for the specific function of On Three’s hacks continues.

Several hardware modifications are necessary to allow the Apple III to access 512K of RAM

On Three's new board includes addressing ROMs as well new address lines

In the end, the rather high $949 introductory price (On Three later dropped it to $449) and fact that it was introduced after the III was discontinued to an already-shrinking market, helped to limit the number of boards that made it into the hands of users.

Update (1/19): I added a gallery of high-resolution photos of the On Three board.  Check it out in the Picasa galleries.

Remember the Titan

I finally managed to get my hands on a Titan III+IIe card this week.  This set of PCBs allows an Apple III to emulate a 128K unenhanced Apple IIe by circumventing the circuitry Apple added to the III to limit the inbuilt emulation mode.

For those unfamiliar, the committee tasked with designing Apple’s new business computer felt it would help boost sales if they included hardware to allow the Apple III to run Apple II-compatible software.  This would allow III users access to the Apple II’s vast business software library and help ease the upgrade process, while also allowing developers more time to produce software specific to the Apple III’s expanded capabilities.

III Plus IIe box

The committee also felt however, that the III should be positioned as a serious business machine and wanted to distance it from the Apple II’s image as a home and educational computer.  The solution they came up with was to emulate a 48K Apple II computer, but include circuitry designed specifically to block the emulation mode from accessing some of the Apple III’s more powerful functions.

In addition to blocking access to a large portion of the Apple II software library, this added a level of complexity to the design of the machine that was already pushing the limits of standard engineering practices of the day.  Woz, who valued simplicity and reduction of chips above all else in his designs, later noted that this was one of the Apple III’s main design flaws.

Titan, the company that also produced a popular line of accelerators for the II series, created a plug in board for the Apple III specifically designed to defeat the limiting electronics and allow the users to better emulate an Apple II within the III.  The first version, the “III Plus II” was released in 1984 and was essentially an Apple II Plus on a card with better access to some of the III’s advanced feature set.  A year later, Titan introduced the “III Plus IIe”.

The Apple III of course was not on the market for very long so many of the peripherals and upgrades were designed and sold by small companies such as Titan, in limited runs well after Apple Computer discontinued the III.  What this translates to today is a very limited marked of expensive and difficult to find peripherals and documentation.

III Plus II III Plus IIe adj

Which leads me to my request.  The Titan card set I received has all the cables and software necessary for operation, but is missing the users manual.  While I can probably muddle my way through set up and use, it would be nice to have something to reference for the inevitable times I get stuck on an issue I can’t fix.  Additionally, because hardware bearing the “III” mark is often referenced as “///” or worse, “///+”, search engines that use Boolean expressions (basically all of them) tend to fail to produce much useful information.  Searching for “Titan III” returns a handful of hits, but “Titan ///” or “///+//e” gives me everything on the web about “Titan” because the “///” isn’t treated as plain text in the search term.  I’d imagine there are specific command sequences in the Google that can give me better results, but my efforts have been unsuccessful so far.

So the question I have is, does anyone have a manual for the Titan III+IIe (///+//e) card that they’d be willing to give or lend me?  Better yet, has it been scanned and posted somewhere that I can’t find because of the aforementioned difficulties in searching for terms with a forward-slash?