I always experimented with microprocessors and assembly programming, expecially playing with the mighty 6502 processor, with electronics, small appliances, tinkering about a way to interface them with each other as well as with a common everyday computer.
I follow different makers, over different channels. I'm an usual 6502.org, Adafruit, iFixit, Hackaday lurker and watch a lot of tech related videos over Youtube. In particular, I fell in love with a couple of series coming from the excellent Ben Eater.
To be specific, this particular playlist re-ignited my passion for electronics and homebrew computers, triggering my desire to come with a completely personal reinterpretation of his project, by designing and making my very first microprocessor based single board computer, which I named GS-65.
Plus, I've always been a fan of a specific design made by Daryl Rictor, who is one of the most active contributors and influential (to me) homebrew designers out there. The design I'm referring to is Daryl's SBC2 board, which basically was the entry point for my personal customization.
My 65C02 SBC design was mainly inspired by these two guys, with a little influence from another interesting designer, who proposed a portable 6502 based Personal Computer. He detailed his work through a very well done website, and his perspective comes with a couple of interesting takes over several aspects related to homebrew computers design. Be sure to have a look at Dirk Grappendorf's 6502 project.
Just to get the general idea, this is a little abstract from my project first sheet.
I chose a super tiny EEPROM of just 8KB (although It's replaceable with a 32KB model), containing a mere 3KB bootstrap which has the task to use a 6522 VIA to bitbang SPI protocol and access an SD Card with a FAT32 filesystem on it, seeking for a file named SYS.BIN that is loaded starting from $0300 address and then executed. In this way I can develop on the real hardware without an emulator and reducing the need to constantly burn an EEPROM at every single firmware refinement, as you can see Ben is doing along his wonderful playlist.
This is just an introductory post about my own GS-65 computer, which has been transferred over a factory manufactured PCB, currently at the second prototype stage. More details will come inside next entries of this blog so, if you like this kind of stuff, be sure to come back here to check if I added something and, yes, if you like to comment, to exchange ideas of advice, you are more than welcome.
