Monday, October 10, 2016

RC2016/10 -- A Good Start...

So, I've been a bit slow with my updates -- I could blame the extra duties involved with running the contest, or I could just blame laziness.  Which one is more believable? :-)


Before any wires can be wrapped for the VCF ELF, some preparation needs to be done. The base platform for the wiring is a piece of "perfboard", which serves as a framework for holding the sockets and other parts in a fixed physical configuration. In order to facilitate placing the various parts, the kit creators included a paper template that is designed to be laid on the back of the perfboard. This identifies the location of each part and explicitly labels the numbering of each pin, making this information available from the back (where it is needed when wire wrapping). In addition, the bottom of the template folds back over the front of the perfboard to provide some simple graphics for the "console" area of the board. This was a great idea, but...

Check The Scale

Laying the printed paper template provided with the kit down on the perfboard that came with the kit revealed a problem -- the paper was not printed at exactly 1:1 scale! Since the paper was ostensibly designed to match the physical layout of parts exactly, this rendered the paper template a bit useless. Fortunately, the kit creators have made the template graphics available as a PDF at their site. I was able to print a new copy of the template, this time at the correct scale. Using this template I was able to get started with placing parts on the perfboard.

Fit And Finish

With the template in place, I started poking socket pins through the perfboard and the paper template. I added the side rails, and continued placing most of the parts necessary for the wire wrap process. The only real problem for me was making space for the toggle switches.

Toggle switches are used for a variety of purposes on the VCF ELF. These purposes include turning the machine on and off, enabling the memory protection circuitry, and controling execution of the program on the machine. Most prominently the row of switches at the bottom are used for entering addresses and data while loading programs. Unfortunately, all those toggle switches need holes drilled for mounting them...

Drilling the holes is no big deal per se -- just drill the hole! Even "good enough" alignment with the spaces allocated on the paper template is reasonably easy to do. However, aligning holes for eight switches in a row is a bit too much for my skills with a hand-held drill. I would like to think that I might have done better using a drill press...maybe... Anyway, I got the holes drilled. Alignment is less than perfect, but that won't effect the operation of the device!

Overall, the assembly process was relatively simple and a necessary step. Nevertheless, it did take most of my available time for the first day of work -- I failed to anticipate the prep time! At least at this point I was ready to move onto the real wire wrap work. If you wanna hear more about that, then I guess you'll just have to say tuned...

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