I've got RSC-Forth running on a 65C02 simulator now.

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The next issue is the hardware. I'll need to rewrite the serial I/O for a 6551 and take out some of the setup code for the Rockwell microcontroller, and reconfigure the ports for a 6522 I guess. It's not currently running on a 65C816 (in ...

I was thinking that I might be able to use the GPIO line for RDY with some kind of "multiplexing", but that would only work if I can pull down RDY during the "SYNC cycle" without stopping the CPU, and SYNC would be a low active signal, which it isn't. This got me thinking, since I've got a couple ...

I'm always puzzled why people coming to retro computers. This is easy to answer. Yes, a Raspberry Pi Zero is cheaper and more powerful, but you've got no chance of understanding the complete system. On a retro machine this can be accomplished, especially by the ones from the late 1970s. The whole ...

Nice project. May I ask if you're using the 'purple' RP2040 board because it has more flash memory? If so, is there any reason why someone couldn't use the RasPi Pico board? Thanks. This can't be done with an original Pico, because the Pico only offers 26 GPIOs on the board. 4 GPIOs are used for ...

That's a nice idea, but a 1MHz machine still feels very fast. If even felt fast enough running CP/M 65 with just ~500MHz due to some (now reverted) design changes, that caused heavy load.

About the PIOs, that's something I want to go for for the upcoming VGA card. But more for the feature that PIO ...

Nope! The Pico runs with 133MHz right now. (Highest clock not considered overclocking.) Running a tight loop in C results in a clock for the 6502 of ~1MHz with my native core, ~1.25MHz with the Apple 1 core. With overclocking the RP2040 you might be able to double that.

For a high-speed 6502 design ...

Yes, I learned about both. The Picocomputer a few weeks before I started my design. I just bought a board without components on tindie for $85.02, which still requires the chips and Picos. So at a very conservative estimate, that'll be $100, against my $10 machine. If you take into account that mine ...

Hello everyone!

Since I've had a discussion on the Forth board about adding Forth to my SBC, I was asked to introduce the machine a bit more in detail here. As I've got a lightning talk where I explain the idea of the machine in five minutes, let's start with this: https://xayax.net/sorbus ...

I did some hacking on RSC-Forth, tried disassembling it, and failed at a very early stage, for all the reasons you (jds) have mentioned. Mostly because I need to move the code, which seems to be way too hard to try for someone who has not done any Forth so far. I've got a KIM-1 clone (the PAL-1 ...

Thanks for all the suggestions. It really kept me thinking.

If I'd implement it right now, I'd go for a two way approach. First I'd try to port the original RSC Forth of the Rockwell Chips, to have something period accurate. That's because the firmware I've ported so far has a vibe of late '70s ...

The thing about RSC Forth is that it is based on fig Forth, but gains efficiency by using a hardware extension to the 6502 processor that speeds up the indirect threaded execution VM that fig Forth is based on. The 65C02 command set supersedes the one of the R65F-series, so the speed up should be ...

I see you use $D000.DFFF for I/O. The Apple II uses $C000.CFFF for expansion cards and softswitches. But it also has separate memory ($400 bytes) for a text page and ($2000 bytes) set aside for a graphics page. Are these pages expected to be handled by an expansion card plugged in, and if so, how ...

Hello everyone!

I've built my own very affordable little open source 65C02 based computer by just using a Raspberry Pi Pico as the chipset: https://xayax.net/sorbus/ .

As I've got a bare minimum kernel running by now, I want to look into additional environments to include. A BASIC interpreter ...