5 ms·
It’s a neat core, but z386 is where the action is right now (https://github.com/nand2mario/z386_MiSTer https://github.com/nand2mario/z386_MiSTer). Interestingly
by nizmow 1mo ago
It’s a neat core, but z386 is where the action is right now (https://github.com/nand2mario/z386_MiSTer https://github.com/nand2mario/z386_MiSTer). Interestingly this core doesn’t output a proper analogue signal. I always wondered why until I recently tried to implement a real EGA pixel clock on the PCXT EGA core. Basically, video cards with dual (or more) pixel clocks are not realistic on MiSTer. The PLLs are there, but once you get too many clock sources the routing becomes quickly impossible. MiSTer framework’s pipeline also forces pixel clocks tied directly to video output (for good reason) and switching that clock at runtime gets very tricky.
- functionmouse 1mo agoAww :( Tragic
- NooneAtAll3 1mo agoI'm pretty sure there was a more recent 386 clone than that
- bonzini 1mo agoz386 is in development right now, and isn't even finished. Do you mean between ao486 and z386?
- NooneAtAll3 1mo agoI remember blog post somewhat recently here on HN comparing 2 386 opensource cores
- initramfs 1mo agothe z386 doesn't output a proper analogue signal, or the ao486?
- nand2mario 1mo agoThanks for mentioning z386. Much of its recent progress was made possible by the reverse engineering and disassembly of the original 80386 microcode (https://news.ycombinator.com/item?id=48247004 https://news.ycombinator.com/item?id=48247004), which z386 uses as its control program. That work has been especially valuable for reproducing obscure protected-mode behavior correctly. With correctness helped greatly by that, development is now focused mainly on performance. In Doom, z386 is currently about 30% faster than ao486 on the same MiSTer setup, with benchmark performance roughly comparable to a 486DX2-66.
- ahartmetz 1mo agoCan you describe why z386 is much faster than the supposedly highly optimized ao486? Is the original microcode (and corresponding chip architecture) that good?