Monday, June 29, 2015

The Commodore 128D Journey Continues

This is a continuation of the alterations I'm doing on my Commodore 128D.

In the last post, I described the internally mounted uiec/sd.  All I had left was to mount the Forward and Backward buttons, but the buttons had not yet arrived in the mail.  Well, today they arrived.

I figured this connection would be relatively easy, and it was, except that I could not, for the life of me, discover instructions on the internet as to whether the button should give +5 to the F/B lines, or Ground them.   Even the uiec Wiki was no help! Luckily, I had purchased an extended daughterboard from Retro Innovations at one point, and was able to use my multi-meter's continuity checker to determine that the correct answer is Ground.

The only remaining task in the computer upgrade was the Second SID.  This would actually be my third or fourth second-SID implementation.  The others had gone into my flat Commodore 128, and several different breadbox C64s.  Those were all either piggy-backed implementations, or custom daughterboards with wires spaghettied all over.  They aren't pretty, but they all still work.

Some time ago, I had purchased a couple of SID2SID boards, hoping it would save me a lot of trouble, while also giving me a nice clean-looking implementation.  However, I also have a SuperMMU board which hangs right over the SID, leaving no space for ANYTHING to be done there.  Therefore I ordered several precision sockets, in order to Lift the SuperMMU 1/3 of an inch further off the board.

Well, those sockets arrived today, and seem to do their job.  However, I discovered another problem.  One of the mounting legs on the C128D power supply obstructs the SID2SID board from lining up correctly.  In the picture above, you can see where the SID is, and where the power supply leg sticks up.  The picture below shows how and why the board does not quite fit underneath the power supply.

I considered trying to shave the board a bit, but wasn't sure how that would end up, and besides, some experimentation convinced me that there wasn't enough head-space under the power supply either for the board, socket, and then chips on top of that.

My next thought, which I still might go with, is to basically make an extension cable for the SID slot that would allow the SID2SID board to sort-of dangle somewhere else on the board.

However, while I'm almost done with the cable, the thought of that daughterboard rolling around inside the case has been eating at me.  Perhaps I could finish this cable and glue the board down somewhere -- perhaps on top of the RF box.  However, I might also just bite the bullet and do another piggyback implementation. :/

I'll have the answer in the conclusion.

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