6502 news

Last Updated or created 2022-09-08

Divers new additions to the 6502 project

Above is my design for a hex keyboard to enter opcodes in hex using a simple monitor program.
i used a 74ls922 which can decode a 4×4 matrix. I’d rather had a 74ls723 which can encode 20 keys.

Nowhere to be found. So i have to think of a new plan.

Now it is configured as follows:


When pressing the alternate key

(to implement)
(1/2 implemented)
(to implement)
step instruction
(to implement)
memory next
memory previous
PCB design for matrix hexboard with place for notes

Meanwhile i’ve ordered new keys (the ones i’ve been using for my photomanager project and wnat to have a setup like this:

4567mem next
0123mem prev

When you want to show the status of busses and alike, you can’t use a led and restistor directly on the bus, it will require too much current.
So i’ve been using below schematic which uses a darlington array.

Now i can display databus, address bus and i’ve been using this for address decoding logic and hex keyboard.

I’ve implemented a second VIA chip, and ordered components to amplify the SID sound part