A few days ago, the printed circuit board (PCB) for my 4-bit do-it-yourself CPU project has arrived. The next step was to get the parts together. That's a bit of a tricky thing as many components, especially the 74HC181 chip that implements the Arithmetic Logic Unit (ALU), while having been quite popular in the 1970's, are a bit on the antique side these days.
In the end, I bought the parts in 3 different stores. Most of the parts came from Digikey in the US and I was surprised how fast they delivered. I ordered on a Monday evening European time and the parts were delivered two days later on Wednesday morning. As I was ordering parts for more than 65 euros, delivery to Europe was free of charge and Digikey took care of customs procedures, taxes. etc. An incredible turn-around time, looks their logistics are quite optimized.
Other, more common parts, like most logic chips came from an electronics store in Germany with an equally impressive turn-around time. The 74HC181 ALU IC was a special case, neither Digikey nor the German electronics store had that part in stock. Thanks to Google, I was able to find the ALU at Darisus, another electronics mail delivery company in Germany that had it in stock. All parcels arrived Wednesday so I was set to go in less than two days. Quite a difference to the days when you ordered by mail and expected a response a week or two later…
The picture on the left shows my current progress. Most parts and the IC sockets are already soldered, the next step is to flash the microcode- and the program ROMs.