Biggest SCSI Drive for a Macintosh Quadra 900?

[dermeister]

8.6, it lets you run everything you can run on OS9 without the overheads. The RAM requirements for OS9 almost doubled with no real advantage unless you had a G3 or G4 Mac. 8.5 and its update was the last version of the Classic Mac OS that was designed with PPC processors in mind.

EDIT: Just a note that I remembered that you will need the "wish I were" control panel to force an install of OS 8.5 and above on a machine such as the Q700 where you can still actively access the 68k processor with the machine turned on. Obviously if you install 8.5 and above you will no longer be able to run 68k apps and you will need to run the install from inside OS 8 or OS 8.1 to get it to work and you will need to do some res hacking.

http://www.lahainacomputer.com/sites/upgrade/upgrade.html

Wow wait, a Q900 with PPC upgrade can't run 68k apps in PPC mode?

 

[Intell]

It can still run them, but it uses Mac OS' built in 68K emulator rather than the built in 68K CPU.

 

[dermeister]

It can still run them, but it uses Mac OS' built in 68K emulator rather than the built in 68K CPU.

Ah, got it.

 

[orestes1984]

It can still run them, but it uses Mac OS' built in 68K emulator rather than the built in 68K CPU.

Where as previously with the PDS slot CPU upgrade under OS 8 and 8.1 it would access the native 68k CPU for the purpose of running 68k apps, once you upgrade to OS 8.5 and above it will only use the PPC CPU.

 

[dermeister]

Where as previously with the CPU upgrade under OS 8 and 8.1 it would access the native 68k CPU

That would obviously be best... Why did it change in 8.5? Anybody succeeded in changing it back? Sounds like it would be the best of both worlds with a dedicated processor for each app type... Although from what I read the Apple 68k emulator was pretty damn good.

 

[orestes1984]

That would obviously be best... Why did it change in 8.5? Anybody succeeded in changing it back? Sounds like it would be the best of both worlds with a dedicated processor for each app type... Although from what I read the Apple 68k emulator was pretty damn good.

Apple made the change with the release of OS 8.5 to ditch FAT binaries (programs that included both 68k and PPC code) that were taking up unnecessary system resources and hard drive space. Bear in mind this was at a time when the largest hard drives you would see were around the 8GB capacity and most people had a system memory of around 32mb.

It's a bit like the change over to purely intel code, I'm unaware of anyone who has successfully gotten around it other than through the use of 68k emulators. You can find out a bit more about it here on Wikipedia.

https://en.wikipedia.org/wiki/Fat_binary#Apple.27s_fat_binary

 

[dermeister]

Apple made the change with the release of OS 8.5 to ditch FAT binaries that were taking up unnecessary system resources and hard drive space. Bear in mind this was at a time when the largest hard drives you would see were around the 8GB capacity and most people had a system memory of around 32mb.

It's a bit like the change over to purely intel code, I'm unaware of anyone who has successfully gotten around it other than through the use of 68k emulators.

Well ditching FAT binaries means the system can only run on PPC, but it wouldn't necessarily preclude the mechanism that forked to the 68040 proc vs the emulator from being in there. Too bad they ditched that, seems they forgot about the use case of 68k machines with PPC cards or didn't care.

I remember when they ditched EFI32 booting in OS X 10.7 Lion, precluding my 2006 64-bit macpro1,1 from using Lion. I was pissed. I'd still be using it today if it wasn't for that (using a 2010/12 Mac Pro now).

 

[orestes1984]

Well ditching FAT binaries means the system can only run on PPC, but it wouldn't necessarily preclude the mechanism that forked to the 68040 proc vs the emulator from being in there. Too bad they ditched that, seems they forgot about the use case of 68k machines with PPC cards or didn't care.

If you read the system requirements available here below for OS 8.6 they fully didn't care. The install I'm suggesting is completely unsupported and was never supported.

http://support.apple.com/kb/TA44294

All of those upgrade cards they fully supported previously got turfed out along with Mac clones. It was right about the time Steve Jobs came back and this was one of his first prerogatives.

 

[dermeister]

If you read the system requirements available here below for OS 8.6 they fully didn't care. The install I'm suggesting is completely unsupported and was never supported.

http://support.apple.com/kb/TA44294

All of those upgrade cards they fully supported previously got turfed out along with Mac clones. It was right about the time Steve Jobs came back and this was one of his first prerogatives.

Note: You cannot use Mac OS 8.6 if your computer has been upgraded with a PowerPC processor card but still has a 68040 (or earlier) processor that is accessed during startup.

They make it sound like there is a technical reason (it being "accessed" during startup)...

 

[orestes1984]

They make it sound like there is a technical reason (it being "accessed" during startup)...

Well technically you're booting off a PDS card, and while smart people managed to fit lots of things into PDS slots over the years including G3/G4 upgrade cards, it's not technically where your CPU should be running from.