WTB IWM disk controller IC for Apple IIgs (or a dead board that has one)

earlier compact Macs (128/512/Plus/SE... not sure about models after that)  uses S/IWM in DIP packages. You'll need to look for one in later models.

Lee Adamson wrote: Aside from the package, are the ICs otherwise equivalent? If so, I could probably make an adapter if I had to.

Here is the pinout for the DIP. The pinout data for the PLCC should be on the image (below). use at your own risk. These are for the IWM, not the SWIM.

At a glance, the pin number and the function of each pin seem to match. Note that pin-1 on the PLCC is at a central point on the top, and the pin numbers increment in a clockwise-manner. 

IWM for Liron and Macintosh

Phase-0 1     28    Phase-1Phase-2 2     27    Phase-3A0      3     26    VCCA1      4     25    Q3A2      5     24    FCLKA3      6     23    /RESET/DEV    7     22    RDDATAWRDATA  8     21    SENSE/WRREQ  9     20    /ENABLE1D0      10    19    /ENABLE2D1      11    18    D7D2      12    17    D6D3      13    16    D5GND     14    15    D4

IWM for //gs

iigs-iwm.png

Lee Adamson wrote:

Oh thank you very much!

 

I think I'm going to try to grind off the corner of the IWM that I have, to try to get a bodge wire attached to one of the pins that corroded completely off.  But if that doesn't work I will surely try to make an adapter and try to snag a broken board with the DIP IWM next time one pops up on fleabay for a reasonable price.

 

I understand that there are some basic incompatibilities between the IIc/IIgs and Mac DB-19 disk ports, though?  As in, attaching certain Mac 3.5 drives to a IIc/gs will fry the controller, and attaching a 5.25 drive to a Mac will also fry the controller?  Does this indicate a difference in the actual IWM chip, or is it something to do with the support logic?

As far as I am aware, the IWM itself is identical. There are other logic components that differ, and IDK what they are. I also have a //gs that someone connected drives to, imporperly, and I'm unsure what burnt out on it. 

Do yourself a favour and buy a hot air station. You can get a basic model that will do the job inexpensively. 

P.S.

I know that these exist, which can be in theory, used for the reverse:

https://www.proto-advantage.com/store/product_info.php?products_id=3600002

I am unsure if you can find a PLCEE to female DIP socket converter that is proper, but you can order a PLCC adapter tat extends out to wires from here:

https://www.adapters.com/catalog/emulator_adapters.pdf

110-6965 is the part number, from their Type 4 line. This will allow you to build your own DIP board on a simple bit of perf, that you can attack to a 28p PLCC socket (that you must attach to the board. You could experient with SWIM signals in DIP configuration in this manner, too. 

Note that SWIM comes in a set of variants, and I do not have handy docs for the differences:

• 343S0061-A : Apple ][ 3.5“ Disk Controller

• 343S0137 : SWIM III

• 344S0607-A : UART/MMU/SWIM (Plus Only)

• 344S1029 : SWIM (Mac Portable)

The only truly interesting thing that I have found:

Apple offered an upgrade kit for the SE, which replaced the IWM sith a SWIM, and updated the firmware. From the Mac SE Technical Procedures Manual, Upgrades Section, page 19:

Note: The 1.4 MB SuperDrive Upgrade Kit available for the Macintosh SE includes two new ROMs, a SWIM disk controller chip, an audio extension cable for reducing EMI interference, the new 1.4 MB SuperDrive, system software, two labels, and an Apple product return form.

P.S. I dug into this rabbit hole, as I had a funny idea of putting a SWIM direct on the //gs mainboard, and trying to add routines to handle it from the 3.5 Drive card ROM, into the //gs ROM 03, as a 'ROM 5', so that I could have a superdrive controller built in. I had considered making a 'Mark Twain' style machine out of that, but I would likely need some help with the ROM code. Only the ROM3 boards could likely handle this, as the ROM size is larger.