6502 Homebrev Overview

Below is the full schematic of my 6502 homebrew computer, as it stands today. I have a couple of expansions in mind, incl. RS232 serial interface, that is not yet hooked up. The main components are:

I will go into more detail on sub-components in future blog posts and later also on the programming/code.

3 Replies to “6502 Homebrev Overview”

  1. Fascinating project – excellent work. I’m working on a 6502 project but much simpler than yours (so far). Got lots of questions for you so would find any more blog posts useful.

    One specific for now though – what made you use a bus transceiver for the display? I added a 2 x 16 line LCD to my data bus and everything stopped working. Adding a 245 transceiver solved that but it may have been re-building the module that solved it not the transceiver. People on the 6502 Family group (Facebook) say that the transceivers should not be necessary. Very interested therefore in how you got you your design.

    Robin

    1. Hi Robin. Sorry for the delay in answering and I might in fact not have the answer. I also thought it should be possible to connect the LCD display directly to the data bus, but no matter what I tried I kept on getting strange values on the bus when the LCD supposedly should be inactive. Adding the transceiver solved it. I’m not sure if the issue has to do with the finer timings of the LCD vs CMOS or even the high-impedance state. But adding the bus transceiver solved any issues I had with errant values on the bus and using a directional one I can both read and write to the LCD display. And the glue logic of clock and address decoder allows for data to be transmitted to the LCD without “manually” flipping LCD Enable. If you discover the root cause I’d love to know.

  2. Oh my goodness! an amazing article dude. Thanks Nonetheless I’m experiencing problem with ur rss . Donꊰ know why Unable to subscribe to it. Is there anyone getting similar rss problem? Anybody who knows kindly respond. Thnkx

Leave a Reply

Your email address will not be published.