Vic 20 core?


@Norman King: I doubt that any other machine implementation (let's call it as "core") can use GS/Mega components. They would be totally separated cores. Re-using any Mega components would be hard, since it's created for that environment which is quite different in needs for other machines to be implemented. Remember, it's not a programming language (I mean VHDL) it's a bit tricky to re-use components in another project, unless it's developed that way from the very beginning. There are projects like that, for example T6502 is a BSD licensed 6502 core and nothing more (more like buying a 40 pin DIP 6502, also here you "see" the input/output signals, you must "connect" in VHDL into your project as it was a real DIP chip package with pins ... well, more or less at least), and it's not hard to use in any project needs a 6502 CPU implementation in an FPGA. Also, VIC-III is VIC-II backward compatible (we can say, though there are differences still), and VIC-IV is VIC-III compatible. But VIC-I (in VIC-20) is kinda different topic, VIC-II is not backward compatible with VIC-I. So a new VIC-I core must be developed as well. C16/Plus4 uses the chip called "TED", again, it's not so much common with VIC-II (this VIC-III and VIC-IV). Memory map differences are really the smallest problem in these case :)

But now, I'm interested, if I can create anything which at least able to drop me into VIC-20 BASIC prompt, I guess it's a nice project for a VHDL beginner, like me ... well, guys, at least I could blink a LED already ;-P Sounds scary enough, indeed :)


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