N8VEM SBC V2 – Still awaiting shipment

Well, Mouser managed to send an email today letting me know that they have shipped my package which has the needed parts to get this board up and running. However, it looks like the package will not get to me until 1/13/18 (4 more days).  Even though I am only 4:30hrs away from their warehouse.  I’m going to be honest, I’m not very happy with their service this time around.  But I suppose every company is allowed to have a bad day from time to time…

I already have all of the sockets and passive components soldered. I’m just waiting on the chips to stick into the sockets.  As well as an oscillator. I plan on testing this board at 16mhz , but may drop the speed depending on how the initial testing goes.  I decided to go with ACT logic families, since they have a very fast propagation delay, low power consumption, and are CMOS and TTL compatible.


The bare SBC V2 Board


Missing only the chips, the CPU Clock, and a 1k resistor array (RR1).  Well, and it needs a bi-color LED…

I actually had several of the chips needed on hand.  The board currently has a 20mhz CPU (z80 of course), an 8255, an 16C550, and a MAX232CPE.  But I still need to have a few more ICs before this will be able to boot to CP/M.  Still waiting on Mouser…

As you may have noticed in the second picture above, I installed a machine pin DIP-8 socket in place of P4 (CPU Clock).  This allows me to try a variety of oscillators until I find one that works as desired.  The goal is to have a very fast processor, and be able to run the SCG (Sprints and Color Graphics) Card in this computer.  Though I hear that card prefers something in the range of 4mhz.  For some reason I have to believe it can handle more speed.  Maybe the person who suggest this used a slower logic family???

As soon as I have more to report I’ll be back with another post.

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