6560/6561 "Options"

[lance.ewing]

The datasheet for the 6560/6561 mentions various options that were available:

6560-001 2.0 MHz Clock for Clocked Memories
6560-101 Light pen option
6560-201 Reset Horizontal and Vertical counters to Vertical Sync
6560-301 Bus available option (Pin is low when VIC is displaying data)

It would appear that they may all have been essentially the same chip. The datasheet kind of implies that, given what it shows on the block diagram with all of those "options" wired in to the diagram. It also mentions that Pin 37 is the one that changes depending on the option.

Something that immediately draws the eye when you look at the 6561 die shot are the bonding pads that were never connected to a pin.

Those two pads to the right of the Light Pen pad and the one to the left are probably the other three options. I've tracked through where they go and they appear to be connected to various important parts of the chip. I can't tell at this stage whether they definitely relate to the other three options in the datasheet.

The pad immediately to the right of LP is connected to a line that also at least partly controls the loading of the cell index from the data lines.

It may be that we all have a chip that internally supports those options; they're just not wired up to do so.

Edit: Updating this post to report that the bonding bad immediately to the right of the Light Pen pad is for the Memory Clock and the pad to the right of that is the Bus Available pad. The pad to the left of LP is the external Reset pad.

[eslapion]

I guess it was just a matter of what pad do you attach the gold wire to.

Now, seeing the insides, we could make a new 6560/6561 that provides all 4 functions simultaneously.