Convert a Schematic Drawing to PCB using KiCad : Reverse Engineering a 6502 CPU card

[@txkflier]

Excellent video. Thanks!

[@twostickes]

Nice intro to KiCad!

[@irgski]

You should connect any inputs of unused gates or inverters to either VCC or GND. Floating inputs may cause the device to oscillate.

[@NEEC1]

Hi. Thats true for CMOS inputs where the input pins can float, putting the gate into an undetermined state. Possibly leading to some kind of oscillation. However, we are using LS series here which are not high impedance input. Its fine to not connect them in this case. They are internally biased (pull up) to high.

[@binarybox.binarybox]

I used Orcad for the schematics and Tango for the routing back in the 90s both on 5 1/4" floppies. I was curious to see if the 6502 would have been better placed with the rom and ram to the left and both inverted.

[@tdrelectronics766]

I see U2 and U3 power pins does not have ant pin numbers but the wires are coming out this is confusing to anyone reading the schematics also the processor U1 would have probably been better upside down with pin 1 at the bottom of the pcb but keep them coming you're getting there

[@bobcrane9945]

I see in the shematic there are 4 nand gates that are part of a 74ls00 chip. When the schematic is imported into the pcb layout they are replaced by the pinout for the package. Can someone point out where this is explained? wher do the breakout symbols come from and how do they get related to the package symbol?

[@NEEC1]

Hi, the schematic symbols, also have associated ''footprints' as they are called and are all stored in the KiCad part library. When you add a part like a 74LS00, you get 4 gates, each with a letter (a,b,c,d) this indicates which gate in the package you are connecting to, and with pin numbers also shown for that gate. Those pins then translate to the PCB footprint and KiCad does that automatically once placed in the PCB layout. Hope that helps.

[@mboowashafiq1496]

hi mate could you be having schematic for this project

[@michaelparris7985]

I didn't see how you took your pencil written schematic and made it into the digital version. I'm new to KiCad and trying to replicate a board but the learning curve to do that is very steep.

[@NEEC1]

Hi Michael. You are right. The video was already getting quite long and wanted to get the point. I had to miss the process of manually entering in the schematic from paper. It really is a process of getting all those bits of circuit (multiple bits of paper) and one by one entering it in. Its a process but eventually you get the whole schematic. I may do another video specifically on schematic entry if there's enough interest. Thanks. And good luck.