One of the SITCOM training computer prototypes
 SITCOM 85 Training Computer
 
  Izabella As I am often asked just how long a project should take to build, for your information, I timed myself for both preparing the board on Day 1, then the wiring up on Day 2. Start time
 
 
 
  Day 1
 
  All bits and pieces gathered together.
Nothing but a collection of parts and a wiring list at 11:49 Day 1.
  The first components fitted.
First step - fit the rubber feet, the two switches and the power bits.
 
  SM components may save some boardspace.
A good way to save a little space is to use surface mount decoupling caps. Quite simple for little fingers... (Day 1).
  End of day one.
Wiring combs and power to the IC’s shown sorted end of Day 1.
 
  The time is now nearly 5:00 PM and it has therefore taken just over 5 hours to sort out and mount the hardware, the decoupling caps and the power wiring (including a break or two for refreshment of course!). End of day one.
 
 
 
  Day 2
  It took me about 4 hours to complete the wiring.

Start time
  Start time
If using one of the ‘eurocard’ type of boards, this is how I arranged my sockets to maximise the space useage. Big down point is identifying Pin 1’s. Thus I ‘blacked’ out every pad immediately to the right of each Pin 1 (Day 1).
 
  All wiring done.
Wiring complete, less that needed for the 100Hz source and the 40 way header (Day 2).
  Close Up
Close-up of wiring around the RAM.
  A close-up of prototype number 2 with most IC’s in their sockets. Please note that the two DL1414 displays are NOT needed to successfully complete the SITCOM project. They simply give a few more experimentation options IF you have one or two handy in the spares box.
 
  Izabella's project works.   An other Close Up
 
  As mentioned above, whilst those two DL1414 displays are very useful, they are NOT essential, as all the SITCOM’s ‘programming’ states may be identified by the single SOD LED, shown on my version immediately to the right of the blue BOOT button. After switch on, this LED will flash slowly, with other faster flashing rates enabled for detecting downloading program data and error conditions.
 
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