WB 3.1 installation compatibility / portability with various version of 68k CPus?

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Hello,
i wonder how works CPU compatibility of AmigaOS, because there usually different versions of libraries for various CPUs with or without FPU.
My question is if is possible to use 1 OS installation image / WinUAE installation with various CPUs, for example for compatiblity i like to use A1200 – 68200, but sometimes i would like to use more performance a upgrade to 68030/40/60..?

  • TenLeftFingers
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68k CPUs are backwards compatible enough that you can generally use the 68000 version of software successfully on a higher CPU. Under WinUAE, CPU-specific software versions make very little difference, but on real hardware, having CPU-specific versions takes advantage of improved features of the newer CPUs but will generally fail on lower CPUs.

As to how it works, it’s mostly independent from the OS regarding CPU version. All versions of the OS prior to 3.5 are fully 68000 code, so run fine on anything from a 68000 to 68060.

The FPU situation is different however, and the OS provides standard routines for dealing with floating point numbers. Using the OS FPU routines is straightforward – just use the FPU libraries and the OS will automatically use an FPU if present, or else emulate one in software if the machine doesn’t have one. However, this library API layer can slow software down a little, so to get the most out of limited resources, many developers compiled FPU-specific versions of their software which accesses the FPU directly, thus saving the time taken to use the OS libraries. These versions will crash however if the FPU is not present, so you need to use the non-FPU version of this software instead.

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