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Questions and Answers for AMIGA Workbench or Coffin

Correct Versions of Software to Use?

Matt Alexandre

Posts 5
14 Feb 2021 22:35


Hi everyone

Apologies if this has already been asked but I couldn’t find it when searching

I have a vampire v500 which I received a couple of weeks ago (thanks Apollo team!) - If offered a choice in terms of 68000 vs 68020 vs 68040 etc on installation of software which version is best to use? Some of the newer software lists the 68080 specifically but I am referring to the older software. Any considerations, pros/cons etc - or given the relative speed of the vampire versus the software itself am I just overthinking this?!

Thanks in advance!

Cheers
Matt


Vojin Vidanovic
(Needs Verification)
Posts 1896/ 1
15 Feb 2021 08:20


040/040 fpu versions do the magic. 060 versions should be avoided, since it misses some instructions 080 has again, thus gives no speed benefit at all.


Gunnar von Boehn
(Apollo Team Member)
Posts 5406
15 Feb 2021 10:33


Yes, Vojin is right.
 
Maybe it makes sense to explain in little more detail.
 
68000 has a very good instruction set already.
 
Since 68020 CPU some EA-modes for table access were more improved.
This means with 68020+ code some table access can be coded in 1 instruction instead of two. This is a nice improvement.
Also some MUL and DIV instructions for 32bit*32bit or 64bit operations were added. Those are sometimes needed and now you can can do in 1 ASM instruction directly where you would have needed a routine before.
 
68030 is same as 68020.
68040 is same as 68030 and 68020 and adds only 1 special instructions which is rarely needed.
 
Motorola was under pressure when doing the 68060 CPU and tried to reach higher clock rate and had limited time to develop the CPU - so Motorola did a compromise and left a few instructions away. For example the 64bit MUL/DIV instruction were dropped to get the 68060 out in time.
 
In general the 68080 CPU can execute ALL instructions.
And it can also execute them faster than any other 68k CPU before.
In my experience the performance difference between 68000 and 68020 code is small - we speak here about a few percent at most.
 
68080 will execute all versions very fast.
As Vojin correctly said -  I would also take an 68040 or 68020 file.


Matt Alexandre

Posts 5
16 Feb 2021 11:13


Thank you both! Appreciate the tip - and the more detailed explanation!

Cheers,
Matt

posts 4