Thanks. I've just come back to this after a long layoff. I've done a ton of 6502 coding in the past, but always wanted to write an OS to get to grips with the underlying design issues. It is early days, but I am enjoying the challenge.

I am in the early stages of writing my 6502 operating system. So far I have achieved the following:

1. Cycle-perfect, interrupt-driven bit-banged RX/TX at 9600 baud using a WDC 65C22.

2. Debug code for RS232 timing (output to logic analyser for RX and TX timing analysis)

3. XMODEM implementation ...

I use Windows, but with WSL for git functionality.

Its mainly to see labels (symbols) in other source files (its shown below the file explorer in VS code). I've got 12 source files now for my OS project and remembering label names can get tricky. It saves jumping between files.

Sorry if this has been asked before.

I'm using VASM for my 6502 project, and I'm struggling to find a VS code extension that does outlining and decent 6502 syntax. Any suggestions? I'm happy to switch assemblers if anyone has some good recommendations (I have used kickassembler before, but hate ...

For what I'm using it for my current half-duplex 9600 code will suffice. It was code that I had started during covid, so just wanted to finish it now I have some more time.

115200 is impressive, that's 8.68 usec per pulse @2MHz.

At the moment the TX and RX is handled by 104 usec loops (1Mhz oscillator) just because!! Im busy writing an xmodem and a cli parser but I'll revisit the RX/TX code and put in the option to use the timer and shift register, with a bit of massaging I can probably get it to do 9600 full duplex.

I did ...

So, during covid I had a lot of spare time and built a 6502 SBC. I got a my SBC up and running with a W65C02, W65C22, RAM and EEPROM and a GAL22V10 for the address logic and a 1602A LCD. It has since sat at home gathering dust. I think I'll ditch the 1602A as it looks nice but doesnt really do much ...

That is a good idea regarding the capacitors. I'll give it a try.

I have some PLC44 DIP adapters so I'll order the NXP UART and give it a go.

Thanks.

Good job. The first revision of my PC board is nearly ready to go. Just need to decide on a UART. I have written some bit banging code for the 65C22, but for sanity I think I'll either put a 65C61 or the NXP UART on the board. How did you find the NXP to program?

How did you do your decoupling ...

Had some time today to play with WinCupl and the GAL22V10. Had a few doh! moments, but its working fine now with the GAL in place and it has reduced the size of the board now that I've got rid of the 74 logic. My wavegen only goes to 10MHz but its running stable at that speed, and im happy with that ...

Thanks.

I tidied up the electrical distribution last night and it now runs at over 9MHz, quite surprised! That is with 55ns SRAM and the standard 74HC address decoder. I'll see how I get on with having the GAL22V10 as the decoder.

Good idea about using ROM space for the I/O, as it's in higher ...

Thought I'd share my first ever build. I used to do a lot of C64 assembly programming back in the day, so have a fondness for the 6502. I've never had much to do with electronics, but was always interested in learning more about the underlying hardware. I have had a go at a 6502 build and I've got ...

It was proprietary, part of the ODS system, although the cartridge I had was just a hacked CBM cartridge with a dump of the EPROM.

Interesting reading.

My longest ever 6502 program was just over 5,000 lines. It was a game written originally in ODS (Ocean Development System) a cross assembler that used a C128 in 80 column mode to target a C64 using the user port to transfer the code. I had some friends in the industry way back ...