Sunday, April 21, 2013

ALU and ID board progress

I don't know what I did to annoy my sinuses, but I haven't been able to breathe through my nose all day. This has really put a damper on my plans for the day, as I really haven't wanted to be far from a box of tissues. Since I'm otherwise clear-headed, I parked myself in front of my computer and worked on the layouts.

The ALU board now has only 161 airwires remaining, of which 21 go to GND and 11 to VDD. That's down significantly from 560/141/79 on Friday. I don't think I want to do much more with it until I pin-out the remaining inter-board connections. In order to do this I need to work on the Instruction Decoder board.

The ID board didn't have a power plane defined, so very few of the VDD connections had been made. I rectified that, then spent some time adding short stubs and vias. It now has 182 airwires remaining, of which 64 go to GND and 28 to VDD. That's down from 622/322/109 two weeks ago.

While the ALU board has a few channels with clusters of vertical signal traces on the VDD plane, the ID board has lots of vertical signal traces spaced across the board. There are also pull-up resistors in many of the gaps, so current will be drawn through these narrower areas. This will require some attention to make sure I don't end up with islands.

There hasn't been much visible change unless you look really closely, so I won't bother posting pictures today.

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