I received the 74HC181, 74HC182 in record time from deivic ! The same day the 74HC259 arrived too !

I must dig the project boxes of the #Discrete YASEP to find all the necessary 74HC251, 74HC253, 74HC193 and others I need for this processor. It's fortunate I always purchase extra parts "because you never know !"

After some "inventorumaging" I have found, in DIP:

• 74HC153: 80? (need 8, in front of ALU)
• 74HC157: 9? (needed for some decoding)
• 74HC253: 80? (need 8, address source select)
• 74HC259 : ×50 (need 16, one per bit)
• 74HC245: a lot (2 needed)
• 74HC573: plenty
• 74HC273: enough for the output ports
• 74HC193: plenty (I just need 4, so far)
• 74HC151: 10
• 74HC251: 30

I expected to use 50×'251...

2 possibilities:

• use 16×151 for the MUX8, and 32×251 for MUX16 : only 6×151 and 2×251 are missing
• use the 253 as pseudo-MUX8, the tristate output can be driven by a DEMUX4 (74HC139?)

Now if I could find a SMD version of the 74HC181, I could almost make a full-SOIC version later :-D however this looks unavailable... I have a bunch of HC283 in SOIC though but that might not cut it, more MUXes will be needed...

Luckily, the last local electronics parts store in Paris still has some HC parts so I could fill the BOM. I have enough 151 and 251 for a DIP prototype, I added some '154 for decoding the DIP switch array. So I guess it's GO :-)