This is not about the history of the Amiga, have a look on Cloanto or Wikipedia if that’s what you need! this is the history of the kickstart versions and how they changed when the model version changed.
There are two identifiers, the version e.g. v3.1 which was used consistently by Commodore/Amiga Technologies (gets a bit fuzzy and inconsistent later), and the release number e.g. r40.68, apart from a couple of anomalies, these increased consistently over the entire Amiga history. Workbench versions kind of kept in step with version and release numbers, again apart from a couple of anomalies.
The TD;DR version is that v1.x of kickstart was for OCS, v2 for ECS, and v3.x for AGA, later versions are mired with copywrite controversy, which I don’t discuss.
Lorraine – pre kickstart (1984)
Lorraine was a bunch of breadboards and logic chips that was the prototype Amiga, it had a 64k ROM, not actually kickstart, but performed that basic function.
Kickstart v0.x (r23,r24,r26,r27,r29)
Amiga Developer Edition – early Amiga (1985)
The first Developer Edition Amigas probably numbered less than 120 and all had serial numbers beginning D- they used a unique motherboard layout, about 2/3rd the size of an A1000, they came with a ROM board with eight 64k EPROMs, it appears that two would be active at any one time, these used v0.4 (r23,r24)
Amiga Velvet (developer edition) – early Amiga (1985)
The name “Velvet” apparently came from the motherboard (and was hand written on the service label), they only had 128k RAM on board and another 128k could be plugged in the front. These early Amigas had a 256k kickstart v0.7 (possibly even v0.6, r26) these used ROM boards the same as the early developer versions. Judging by the serial numbers here were less than 500 Velvets.
Amiga Zorro (developer edition) – early Amiga (1985)
The “Zorro”, was a later version with a WOM for the kickstart loaded from floppy via an onboard “bootstrap” the same as the A1000 (memory increased to 256k on the motherboard with another 256k optionally in the front), the beta kickstarts 0.7-0.9 were 256k (r27,r29), v0.7 is dated July 1985. This name was later adopted for the slot/interface name. These early development systems slowly morphed into the production A1000, and were also given serial numbers D-nnn (probably less than 150 Zorro machines), this later version being closer to the released A1000, the cases for Velvet and Zorro didn’t contain the moulded signatures like the production release.
Kickstart v1 (r30,r31,r33,r34,r35)
Version 1.0 of kickstart for the A1000 was released in September 1985 which went out with the first commercial A1000’s, this was also a 256k ROM loaded into a “Write Controlled Store” (WCS, basically RAM which after writing is then flagged as read only) via floppy, later followed in November by version 1.1 in PAL and NTSC versions as the European market opened up. Version 1.2 followed in 1986.
The A2000 (first) came out in March 1987 and came with a slightly updated kickstart v1.2 in ROM, I’ve been told that very the first (German, prototype? dev?) A2000 had a board that plugged into the CPU slot and provided a WCS which then worked the same way as the A1000, but I’ve not seen one nor any references to it myself – any info would be gratefully received.
The A2000 was quickly followed in April by the A500 using the same physical v1.2 ROM.
By the end of 1987 kickstart got a major overhaul, v1.3 was released, still a 256k ROM, there’s a beta 1.2.1 release which is almost identical to the 1.3 kickstart.
Kickstart v1.4 (r36)
A3000 ECS (1989)
The very first alpha version of Kickstart v1.4 (May 1989, r36.15) was a 256k ROM which looked just like an update of 1.3, but by December this had developed into a 512k ROM and the revision number had been reset to r36.2, the final version (r36.16) became what’s known as a “public beta”, being burnt to mask ROMs and delivered with the new A3000, although possible to boot directly from this, it’s main purpose was to bootstrap either legacy v1.3 or the new v2.0 from a hard drive or floppy, this was known as the “SuperKickstart” process, only this specific version (r36.16) can use superkickstarts as it’s the only version with the additional exec module, “kickmenu” and “kickad”.
As far as I can tell, r35 was only used as a designation for a couple of CDTV extended ROM modules and probably shouldn’t be considered a release number in it’s own right.
Kickstart v2 (r36,r37,r38)
The Enhanced ChipSet that came with the Amiga A3000 (released 1990) prompted the first significant visual and architectural change in kickstart, there was a huge amount of development, this meant that burning mask ROMs wasn’t really that practical, and so kickstart updates were typically delivered via “Superkickstarts”
This rather odd setup allowed the A3000 owner to transition from kickstart 1.x to kickstart 2.x while retaining compatibility for both, later versions of the A3000 came with v2.04 in ROM (rather than v1.4), the new (overhauled) Amiga A500 Plus also came with a slightly different kickstart v2.04 (r37.175), during this transition the revision number of kickstart 2.x changed over from v36 (first used in kickstart v1.4 and continued for the early v2.x) to v37
The final, or at least highest version of v2 was r37.350 for the A600, the 68020/68030 machines got r37.175 and there was a r37.210, but that appears to be be an A600 beta, these were all kickstart v2.0n, there was never a kickstart v2.1, although there was a Workbench v2.1 which was designed for kickstart 2.0n.
As far as I can tell, r38 was only used as a designation for some language modules and a couple of CDTV extended ROM modules and probably shouldn’t be considered a release number in it’s own right.
Kickstart v3.0 (r39)
A1200/A4000 AGA (1992)
The next major kickstart change came with the Advanced Graphics Architecture, like kickstart v2, v3 was also a 512k ROM, 3.0 came out to support the AGA features.
Kickstart v3.1 (r40)
Around the time the CD32 was being developed, the kickstart had a major update to 3.1, this was also a 512k ROM, however, the size of the updates caused an issue for the A4000T and it needed more than 512k, as this wasn’t (electrically) possible on A4000 motherboards, this meant leaving out the Workbench library; instead, loading it from hard disk via a much smaller kickstart module “WBFind”.
The CD32 had even bigger problems as it needed much more space for it’s CD menus and game system, plus support for additional hardware, this was solved by using a 1Mb kickstart, technically the kickstart is two banks, one at 0xF80000 and one at 0xE00000.
Hold on to your hats, it gets more complex than this, the CD32 was originally designed to have two physical ROMs (like the A1200), but, instead, it bank switches a single physical ROM. The unpopulated spaces for the components are still on the board and it’s possible to hack it back to a dual ROM system and function like an A1200.
CD32 developers had use of a plug-in development board, basically giving some of the A1200 ports (not PCMCIA), an IDE interface and alternative CPU (also a 68020, perhaps as a monitor?), this extra functionality was not supported by the normal CD32 ROM and so alternate “cdgsdvl” kickstarts were available to developers.
Only a handful CD1200 devices were made, possibly only one or two still surviving, designed to bring CD32 functionality to the A1200 they require a plug in card (perhaps including an AIKKO chip with c2p functionality, and the CD “data” interface, possibly RAM too – so far no expansion card has been found). There’s two known CD1200 kickstarts, both v3.1 1Mb (r40.70), they are unusual as the main kickstart loads at 0xF00000 and the extended ROM at 0xA80000, this implies that the ROMs would be on the expansion board and not a direct replacement of the onboard ROMs, or perhaps these were test kickstarts designed for a different A1200.
This kickstart is different to the CD32 developer (cdgsdvl) kickstart as it includes dedicated A1200 functionality such as PCMCIA support.
The r41 release wasn’t skipped as such, apparently it was for multi-byte Asian language (internationisation), I’ve only found a couple of printer modules which use the v41 number, so that kind of makes sense.
Release r42 was in development when Commodore/Amiga shutdown, you can find code and references to it in the leaked source, and you could even grab and roll some of those modules into a ROM to see if they work, however, this was a development snapshot in time, so it won’t be stable, perhaps the r40.70 code in the leaked source is stable as r40.70 did make it out for the A4000T, although that doesn’t mean the A600/A1200/A3000/CD32 etc. versions would be.
Kickstart v3.2 (r43)
The last gasp of the 680×0 Amiga, by Amiga Technologies was the Walker, only existing as a prototype, two, maybe three surviving (and perhaps some bare boards) there was an update of v3.1 to v3.2 also a 512k ROM, not really of any use to any other Amiga (possibly not even bootable on any other physical Amiga), although many modules were updated.
Kickstart v3.1 (r40.71)
The Kickstart development environment was “refreshed” and updated by Gateway (Olaf Barthel) at the end of 1997 and into 1998 to be more consistent, this resulted in a recompilation of the existing kickstart modules and some copyright notice changes, apparently there were also some bugs fixed, but I don’t have the specific details.
Kickstart v3.5/v3.6 (r44,r45)
Haage & Partner (1999/2000)
When Haage & Partner got a licence to update the OS, they released OS 3.5 and OS 3.9, no physical ROMs were released, but ROM module updates created as part of the release were often used to create custom, unofficial kickstarts.
Additional components and updates via “Boing Bags 1/2” used r45
There was also a fake “Commodore” 3.5 ROM circulated, no technical updates, except ShapeShifter compatibility.
Kickstart v3.X (r45)
The Cloanto 3.X kickstarts contain many “community” updates bundled into consistent, Amiga model specific ROMs, sold as part of Amiga Forever, the most significant updates are to support large hard drives. These kickstarts are all 512k and require loading workbench library from hard drive.
Kickstart v3.1.4-3.2.2 (r46,r47)
The very latest kickstarts are from Hyperion Entertainment, these are actively developed for many different classic Amiga’s, except the CD32, these are all 512k ROMs and leave the workbench and icon libraries out of the ROMs so they can be loaded from hard drive, as such they are really only designed for hard drive based Amiga’s. As of March 2023 five releases/updates have been made available, 3.1.4/184.108.40.206/3.2/3.2.1/3.2.2, there were also two versions of 3.1.4, but I think the reason was just a copyright notice change.