First hardware: 6 bit ÷ ten (decimal)

First attempt, on a 220 mm × 100 mm (ROTH ELEKTRONIK - RE310-S2) - appropriately named LABOR CARD, ended in early abandonment; it was becoming way too cramped.

So, my new approach is to use 3 off (or, for some boards, 4 off) 100 mm × 150 mm boards (FR4), assembled into a 'tray'. Two 10 mm × 10 mm × 1 mm aluminium angles form the tray; the boards are attached via nylon PCB mounting blocks (Richco: PCB MB 01) and 3/4 inch M3 (No. 4) self tappers:

The aluminium rails will help when it comes to a final assembly of the thing - it's anticipated that they will slide into some type of card guide, so that several trays can be stacked up. Probably something like 27 trays in total.

And so we have:

Board power (5 V) comes in bottom right; power indicator top left. There's a 6u8 (35V!) solid tantalum capacitor, plus 100 nF ceramics next to each chip. Data in/out via IDC connectors.

I simply love the old TIL 311 hexadecimal displays (although they draw something crazy like 90 mA each!). 

And here have 3F ÷ A = 6, remainder 3. Amazingly, this all worked first time!

Total current consumption is 420 mA max - depending on what's displayed. If/when I get the whole thing working, I can pull the display chips - they wouldn't be readable anyway, when the boards are stacked up - included for the moment for test purposes.

All the chips are LS, except for the 7425 (dual 4-input NOR), which is the basic Texas SN7425N; I couldn't find the LS version of this one.