Update on MKHBC-R1, 6502 based home-brew computer: UART

I made some modifications to the circuit diagram (added jumper switches) and created a PCB component layout for my UART card. The layout is not too elegant and appears wasteful, because I will make the circuit on the slightly over-sized prototyping board which has some traces and padded holes on the bottom side. I originally planned to make all expansion cards for my computer on such boards, since they have some traces in addition to pads and padded holes (which BTW do not cover all the board's surface evenly). Due to that they are suitable for less dense component placement than is required on CPU bus cards. If you care to compare this one to my CPU card board, which is made on the different prototyping board, smaller but equipped with padded holes spread evenly across the entire surface and no traces, you will understand why. I simply can make more point to point connections and pack components closer together on the board with padded holes only versus a bigger board but with less holes and with some traces on the bottom.
Next step - point to point soldering of the UART card. This should be far less work than CPU card.

Circuit.

Layout.

 

Testing CPU card in the mother-board. The "mobo" still lacks power supply, interrupt controller and I/O port - just passive CPU bus and buffered I/O bus (black slots in the back).

In front, the prototyping board which will host UART circuit.

11/12/2015

MK