View Single Post
Old 15 October 2016, 21:33   #25
Registered User
Join Date: Aug 2004
Posts: 2,821
Originally Posted by JZon View Post
Aladdin 4D wants to work optimally with a 68040 processor. I've tried all possible combinations. 68020 and 68030 are stable. I can't get 68040 working.
Optimally working with a 68040 only applies to real Amiga hardware, not WinUAE. You don't need to worry about that, unless you enjoy figuring out how to properly emulate a 68040 system (and installing 68040.library etc.).

In fact, running in WinUAE Aladdin 4D will probably work faster with emulated 68020/68030 + 68881/68882 than a 68040.

On real hardware, a 68040 is much faster than a 68020/030. However the on-chip FPU (math coprocessor) of the 68040 doesn't support all instructions that the 68881/68882 do. (The 68881/68882 is a separate chip installed on some 68020/030 machines.)

Because of that, 68040.library contains code to emulate the "missing" FPU instructions. But that emulation isn't ideal because it's quite slow. Some Amiga programs (maybe Aladdin 4D?) come with a version compiled for 68040 CPUs which only uses FPU instructions that the 68040 supports. On a real 68040 Amiga that's faster than the 68040.library emulation.

In WinUAE though, non-FPU emulation speed is more or less the same whether you're emulating 68020, 030 or 040. Since all FPU instructions are emulated there's no speed advantage to using a built-for-68040 version of a program vs the 68020/030/881/882 one. In fact the 881/882 one could be faster.
mark_k is offline  
Page generated in 0.22208 seconds with 9 queries