tag:blogger.com,1999:blog-4017745189504803687.post2160818831592773737..comments2024-02-28T07:29:15.484+10:30Comments on Making a C64/C65 compatible computer: RR-NET emulation dramasPaul Gardner-Stephenhttp://www.blogger.com/profile/10150903760695355706noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-4017745189504803687.post-39711028467750271872014-09-24T21:09:54.066+09:302014-09-24T21:09:54.066+09:30You are quite right, and this is the approach I am...You are quite right, and this is the approach I am taking, to make it reasonably compatible, but without sacrificing the ability to add interesting new features. In fact, it is the philosophy page from the C65 specifications book that is my guide in this.<br /><br />At the moment all enhanced features are available from C64 mode, as they are on a C65. This might change a little if I implement my plan for a hypervisor, as it would be possible to control which features (and which parts of RAM) are available to a given session, partly for segregation, but also partly for compatibility assistance. For example, it might be necessary to hide 4510 extended opcodes from some programs or other things like REU that might upset some software.<br /><br />Paul.Paul Gardner-Stephenhttps://www.blogger.com/profile/10150903760695355706noreply@blogger.comtag:blogger.com,1999:blog-4017745189504803687.post-71979482669346955222014-09-24T20:06:25.295+09:302014-09-24T20:06:25.295+09:30Well.... as you are building a C65 system, you sho...Well.... as you are building a C65 system, you should be carefull to to fall into the C128 trap: The C128 was 100% compatible, but because there was no new functionality in C64 mode, nobody was able to enhance his software for C128 while keeping it compatible with the hugely popular C64. And therefore buying a C128 was not atrractive enough, further reducing the market for native C128 software.<br /><br />While commcerical succes might not be your goal here, I do think it makes sense to stay close to the C65 philiosofy. So build an enhanced machine rather than perfect emulation, perfect emulation has been done before after all. A separate VIC-II core might give perfect compatibility has the same risk of offering no enhancements. IMO it should be compromise between compatibility and new features.<br /><br />Some support fort fast loaders will be necessary though. The 1541 is so slow that the C64 experience is greatly reduced without them.Daniël Mantionehttps://www.blogger.com/profile/07865411495348454676noreply@blogger.comtag:blogger.com,1999:blog-4017745189504803687.post-15704096567693393332014-09-24T07:07:34.372+09:302014-09-24T07:07:34.372+09:30Hello Daniël,
Actually, GEOS isn't quite so ha...Hello Daniël,<br />Actually, GEOS isn't quite so hard, because it is possible to replace the default fast 1541 driver (or better, 1581 driver) with something else. There is a port of GEOS to the old parallel cable 64NET v1 for example, that could be used as a very handy starting point. It might even be that I make a kind of exception system for the C65GS, so that accesses to the user port trigger a hyper-visor exception and the 64NET server then effectively lives inside the C65GS itself. In that way, the 64NET version of GEOS wouldn't need any modification at all.<br /><br />But back to allowing a real 1541, I do plan this, however the timing may (or may not) be accurate enough to support some of the fancier fast loaders. This will depend a bit on how I do the 6510 emulation. I oscillate between having a separate 6510+VIC-II core for c64 compatibility mode, versus adding a 6510 personality to the 45GS10, and putting some work into making the VIC-IV a little more VIC-II compatible, e.g., supporting VSP and some other of the more common effects. But it will likely be a while before I have to make the final decision.<br /><br />Paul.Paul Gardner-Stephenhttps://www.blogger.com/profile/10150903760695355706noreply@blogger.comtag:blogger.com,1999:blog-4017745189504803687.post-13749225210251847672014-09-24T01:54:21.614+09:302014-09-24T01:54:21.614+09:30Geos shouldn't be that demanding for the VIC a...Geos shouldn't be that demanding for the VIC and SID. I guess your main problem is that, due to its fast loader & copy protection, it is quite demanding for a 1541 emulator. But what if you used a real 1541?Daniël Mantionehttps://www.blogger.com/profile/07865411495348454676noreply@blogger.com