I have an Amiga that has the Kickstart 3.0 ROMs installed. What advantages are there to replacing the Kickstart ROMs with 3.1? Is there any software that requires Kickstart 3.1 to function?

  • Get 3.2 ROMs. :) That will let you have true >4GB device access. Oct 12, 2022 at 12:25

3 Answers 3


Kickstart 3.1 can detect some memory expansions automatically so that AddMem is not needed in your startup sequence, and it has a few other improvements that are required for Workbench (AmigaOS) 3.5 and 3.9.

  • I would also add a DISADVANTAGE - if you happen to use PCMCIA slot with certain Accelerator cards with more than 4MB memory - KS 3.1 will complain and not boot, but 3.0 will ignore the error. Basically the PCMCIA and small area of FAST RAM above 4MB share the same address space. Aug 15, 2016 at 4:44
  • 1
    @KubaTyszko this is not a disadvantage. You most certainly DO NOT want two devices to share the same memory range. :-)
    – user180940
    Feb 19, 2019 at 15:16

You need the 3.1 ROM if you want to use OS3.9, and more importantly OS3.9's support for the use of larger than 4GB of HDD space by the Amiga OS.

Without 3.1 ROM and OS3.9 you can still use larger HDDs but the Amiga OS can only access the first 4GB (so you could use the rest for linux partitions, for example.)

Note that even with the 3.1 ROM and OS3.9 there is still a max partition size limit of 8GB, but you can use however many partitions you like to map out the whole drive. The boot partition however must be allocated entirely within the first 4GBs of space.

Additional Note: Some software that came with a utility to install it to a hard disk may refuse to install to partitions greater than 2GB (as that was the original partition size limit) after failing a free space check due to an insufficiently sized variable.

  • The 8GB/33bit addressing space is a limitation in the standard FFS driver/functionality?
    – nsandersen
    May 6, 2016 at 9:22
  • I'm not sure, to be honest. I assume its a limit with the improved version of FFS included with OS3.9, but I haven't tested larger partitions with other file systems (like exf2, etc.).
    – mnem
    May 7, 2016 at 0:43
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    IIRC, you will need a 3.1 ROM to run Amiga OS 3.1.4 (latest, even after 3.9), though 3.1.4 comes with it's own ROMs as well Nov 20, 2020 at 19:47

OS-wise, Kickstart 3.1 should have more optimized graphics.library routines (rewritten to assembler), and some more tags for VideoControl() to speed up remaking the display in some cases (eg. do not reload the palette for a screen, but use the previous' screen one).

They probably were meant to convince developers to use OS functionality for games and multimedia titles for the CD32 (that debuted the new Kickstart), along with lowlevel.library.


Also, Workbech (Execute, Information) is now font sensitive.

A full list of Kickstart 3.1 changes is in the archive here: http://www.gregdonner.org/workbench/wb_31chg.lha . The file lists many fixes for non-AA chipsets, with 39.x module version numbers... later versions than the ones in 3.0 maybe? (I cannot easily check module versions in 3.0)

Indeed, now that I think about it, I remember that Kickstart 3.1 may have been described back in the days as an improved 3.0, finally suitable for all machines (i.e. OCS and ECS too) as opposed to 3.0 which was never released for A500/A2000/A3000 and was never supported on non-AA machines.

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