The smallest homebrew CPU in the world is working now !
Last week, I spend a few evenings changing the layout, to correct the pinout of the flash chip. Not a really easy task, this is a very crowded (only 2 sided) layout. One week ago, on thursday evening, the new layout was sent to China, and I got the pcb's yesterday. It was assembled today (I had ordered a double set of components the first time, perhaps already having the feeling that the first time would not be right).
It is now running a simple program, it fills 6 memory locations with the 7-segment values for the digits 1 to 6, and then writes each of them to the multiplexed display in a loop.
To show that there's nothing hidden, I disconnected the RPi, and I also show the back side of the pcb.
The display is a bit dim, that's because in the time allotted for each digit, it is only on during 3 instructions and off during 4 instructions. But in reality it is looking better. Perhaps I'll also have to make the resistors a bit lower in value. You can see the program on the Browser-based JS assembler page.
Back side of the pcb:
I will soon update the schematics and gerbers, and describe the application pcb, the NAC, and the modifications.