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My recently restored Mac SE/30 has System 7.0 running on it at present, booting from an original SCSI HDD. I’m missing a few key features, like disk image mounting, which I understand were added in later system versions, and some software I’ve tried to install says it requires system 7.5

Based on this, I’m thinking of upgrading to a later version of OS. It seems that System 7.5.5 is the latest I can run on an SE/30 from what I’ve read here: How to install System 7.5.5 on a Macintosh SE/30 using floppies?

Others advocate not going beyond System 7.1, and some articles claim it is possible to run versions of System 8 on an SE/30 if you have the correct ROMs fitted in your machine! (How would I know if I have the required ROM versions, and is there any benefit in running > System 7.5.5 on such a machine??)

Would love to hear the views of those who have researched this, especially if they have first-hand experience of installing on their own SE/30!

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Well, it seems as if you have already researched everything there is to know.

Installable systems:

  • Originally the SE/30 was introduced with 6.0.3
  • Official support for the SE/30 goes until 7.5.5
  • Since 7.6(.1) it is still just a minor update. It can be easily installed.
  • System 8.0/8.1 does work as well, by copying a few files from 7.5 (*1)

The choice which System to use is mainly defined by the machine configuration.

  • Without a hard drive only 6.0.7 makes any sense
  • Similar with less than 4 MiB RAM, as 6.0.7 only needs like 3-500 KiB RAM, leaving acceptable amounts RAM for an application
  • With 4 MiB or more System 7.1 may be the best choice, as most software will run under 7.1, while it is still somewhat lean (*2)
  • With 8 MiB or more the newer systems may be acceptable (*3).

But there are also software issues, as System 7.5 introduced a lot of new and quite handy improvements (like a scripting ability for Finder operations). 8.x added even more nice stuff, like multithreaded Finder (background copy) or the neat platinum UI. On the back side, everything after 7.5 does need clean 32 bit ROMs. Further, 8.1 is the last system supporting 68k Macs (*4).

The ROM issue is a bit more complex - and tied to RAM size as well. The Mac ROM includes large parts of the basic system code, thus relieving the need of RAM to load this code from disk. Originally no-one envisioned a Mac with more than 24 bit addressing (*5) like the original 68000 offered. Thus many routines either didn't really take care of the uppermost 8 bits, or worse, used the top 8 bit in every 32 bit word for some bookkeeping. Such code was present in the ROM code and not fully removed until the early 1990s.

All SE/30 are equipped with such ROMs, originally preventing the use of more than 8 MiB RAM. Since the machine can be fitted with up to 128 MiB (Awesome for an 68k Mac) Apple had to come up with a solution to satisfy complaining customers. Instead of supplying them with clean ROMs they bought a MODE32 called third party utility, offering a 32 Bit layer around 24 Bit functions. Of course nothing comes with a backlash, in this case, a few programs relied on these functions operating as they did before - leading to crashes:(

So while 7.5 runs fine with MODE32, 8.x directly checks the ROM ID and refuses to work. There are ways to make 8.x boot with MODE32, except they are not really legal. The only legal way is acquiring a clean ROM. Lucky here the Mac II (IIsi, IIfx, etc.) family machines use the same ROM module format. So acquiring one from eBay (or any scraper in your neighborhood) will do the trick. Except no it'll fail in some programs compiled for an 68040. This can for most parts be resolved by swapping in 7.6 files, but it might be a rather large effort even for people custom to this.


*1 - Plus clean ROMs or an emulation thereof.

*2 - If you got more then 8 MiB and the Finder tells you that the System needs like 12 MiB or alike, than you might want to install/activate 32 Bit addressing - as without only the first 8 will be used. The larger number displayed for System is due the fact, that everything that can't be accounted for otherwise is declared as 'system :))

*3 - Of course there is always a chance to try to slim it down to what is needed - still, it wouldn't change the general notation.

*4 - It is said that with a lot of extensions hacking it should still be possible to run 8.5 on a 68k system.

*5 - In reality only 23 Bit (8 MiB) as the top bit was used for management.

  • In addition to the explanation from Raffzahn, I'd also consider the wait time until the machine has booted. 7.5.5 may add (desired) features but it takes a lot of time to boot, though. Drop•Disk adds Image mounting capabilities to 7.1 which I'm running on my SE/30. I also recommend against trying to run Appearance Extension (or OS newer than 7) on 9"-Macs: The Window borders take more precious screen space. – PoC Nov 6 '18 at 12:41
  • @PoC You're right they are a waste of screen space ... but they are soooo pretty :)) And yes, the SE/30 is somewhat of a chimera. While it can house an extreme comfortable 128 KiB of RAM, that's awesome for a 68k Mac, but at the same time it's CPU is only a 030 @ 16 MHz. with a puny 512 x 342 display. So unless it's especial about the aperance, an LC475 is like the sweet spot of 68k Macs. Still small, top of power (040 can be made to 33 and 40 MHz) and large RAM. – Raffzahn Nov 6 '18 at 14:47
  • The term "pretty" is subjective ;-) — For me, I don't like the Looks of OS 8 and newer. In terms of RAM: Did someone even try to put 128 Megs into the SE/30? I imagine the memory test will take an awful lot of time and without any ROM patches, this test is done every time, AFAIR. – PoC Nov 7 '18 at 16:53
  • @PoC Jup, it is. I personally did like the OS 8 look so much, that I used for 7.6 a little extension that added the Platinum look. I used a LC-II with 36 MiB and a 630 with 132 MiB and both booted not notably slower with the large RAM. The longest waiting time was still for all the extensions to come up and configure.. Also, there is no need to boot all the Time, it isn't an Apple II (or a PC). Once a day does the job. – Raffzahn Nov 7 '18 at 21:30
  • this Extension could have been the Appearance Extension from Apple. It adds the Appearance Manager Routines, so Programs for OS 8 and newer might run under pre-8-systems. I have learned that Boot-Time is dependent on RAM size (initial test: More RAM, more time), disk speed (Rotational speed, spin-up time), AppleTalk (off: no address must be chosen and boot continues immediately, on without router: eats up about three seconds) and of course count and kind of extensions. – PoC Nov 9 '18 at 9:25
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Based on my experience with the SE/30 and the Mac IIci/IIsi, I'd recommend System 7.1, and I'd also recommend installing it alongside a 32-bit clean ROM using the Mac ROM-inator II.

The benefit of System 6 is the small size, low RAM requirements, and quick boot up. However, lots of software specific to the era will need System 7 plus System 7 is just far more capable. So to address these shortcomings, you use the bootable ROM disk of the ROM-inator II. It boots instantly and allows for sufficient customization based on the hardware you have (i.e. extra RAM, networking, built-in HD).

You will not be able to run the software you mention that requires at least System 7.5. For me, this is not an issue because such software frequently works best with these additional capabilities that were prevalent by the time System 7.5 was out:

  • Color display
  • Minimum 640x480 resolution
  • Faster processor, such as 25MHz 030 or an 040.

So, for System 7.5 stuff I'd recommend a newer Mac than the SE/30, which has the above capabilities.

  • All true. Except that the main issue of 7.5 is not so much CPU or video (it is), as its hunger for RAM. The SE/30 is the only classic with huge memory installable. To people who want to run an 68k Mac, I always recomend a LC475 (or alike) or a 630 (best the CD/DOS), as they even run 8.1 at good speed and offer almost unlimited RAM (Everything above 16 MiB is large for 68k and 128 is like unbelivable - in fact, I never managed to realy fill it). Similar most 68k applications are made to run acceptable on a 16 MHz 030, so having a 25 or 33 (or 40 with ahacking) 040 makes it lightening fast. – Raffzahn Nov 6 '18 at 16:12
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    Sure. But personally, I care about the apps first and let that dictate which OS on which machine. My answer is aimed at people in that same 'camp'. – Brian H Nov 6 '18 at 18:52

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