TTL Part the first: 10 bit x 6 bit multiplier

So here we have it...the 10 bit times 6 bit multiplier, put together using Helmut Neemann's excellent Digital - simulator for digital circuits: 

https://github.com/hneemann/Digital 

It's got an excellent in library of 74-series chips. Speaking of which:

Chip count:

17 × 74283 (4-bit full adder)

15 × 7408 (quad AND gate)

plus LEDs (to show amongst other things the partial sums in binary) and the aforementioned TIL311 hexadecimal displays (to show A, B and A × B) - although not strictly needed, these will prove invaluable if/when I get around to real chips and real solder and real mistakes.

And this is what happens when you switch it on (i.e. press the space bar in Digital). The two inputs (upper left) are A = 3F (111111) and B = 3FF (1111111111) and the product (lower left) is FbC1, which is the correct answer 😌.

The partial products (the three sets of LEDs in the middle, respectively) for this example are:

R = 1111111111 + 11111111110 = 0101111111101 (1023 + 2046 = 3069 decimal)

S = 111111111100 + 1111111111000 = 010111111110100 (4092 + 8184 = 12276 decimal)

T = 11111111110000 + 111111111100000 = 01011111111010000 (16368 + 32736 = 49104 decimal)

the sum of these giving the product, 64449 decimal or FbC1.

The intermediate quantity, U = R + S = 0101111111101 + 010111111110100 = 011101111110001, is shown by the lower left row of LEDs.

Some further examples:

3F × 001 = 003F

2A × 2AA = 6FE4

00 × 392 = 0000

34  × 3B3 = C05C

2d  ×  3b5 = 36d1