Fallen giants - comparing the '80s second-generation home computers

[liam_on_linux]

A friend of mine who is a Commodore enthusiast commented that if the company had handled it better, the Amiga would have killed the Apple Mac off.

But I wonder. I mean, the $10K Lisa ('83) and the $2.5K Mac ('84) may only have been a year or two before the $1.3K Amiga 1000 ('85), but in those years, chip prices were plummeting -- maybe rapidly

Comments

[waistcoatmark]

Did the ST really have an OS? It could copy files and launch programs, but it was about as much an Operating System as DOS was. Granted I never programmed it, so it might have had some elegant backend hidden behind it's limited GEM exterior, but if so, it was *very* well hidden...

[uon]

What counts as "really an OS"? It had what counted at the time, which was basically a file system, some thin hardware abstraction, and a couple of utility functions. The 68000 had no proper MMU, so a lot of what you'd expect from a modern OS was regarded as impossible. (It wasn't actually impossible, but you had to resort to bizarre tricks to make it work, like using two CPUs, which wasn't really viable for a home computer then).

There was almost Proper Unix. Oh, if only...

[pndc]

An operating system doesn't *have* to sandbox processes from each other. It just has to ensure that processes play nicely and can share resources.

IMO, one of the important things to share is control, and AmigaOS was the only widely-available microcomputer OS that had proper pre-emptive multitasking. RiscOS, Atari TOS and MacOS Classic were single-tasking systems which that had co-operative multitasking bodged on later as an afterthought, and it shows. You can't safely preempt a program that believes it has full control of the machine.

(Yes, AmigaOS contained loads of flaws that made its multitasking much less effective than it could have been. It was still less awful than the others.)

A Unix process is a specialised virtual machine which believes it has full control, and preemption switches in a completely different virtual machine. This is why Unix excels at multiprocessing, but threading and signals within a virtual machine are a bit of a disaster.

[liam_on_linux]

I love that story. Not sure if you originally pointed me at it. I don't understand all the implementation detail but it sounds like a cool hack.

DR's CP/M family definitely grew into "proper OSes" on other hardware. A descendant of Concurrent CP/M called FlexOS survived until quite recently on IBM point of sale kit. It even had a multitasking GUI, X-GEM.

[anonymous]

They were both "first gen" (if you count amiga/st as second gen, as per the title). 8-bit, resorting to hacks even to access 128k of ram etc.

[liam_on_linux]

Exactly.

The thing with the 8-bitters is that there were so many of them, it's tricky to distinguish clear influences

[waistcoatmark]

Going by Liam's definition of St/Amiga as 2nd generation, then those were definitely 1st gen: 8-bit processors, unable to access more than 64k of memory without having to jump through nasty hoops.

[pndc]

The first Mac nearly shipped with the same awful 8 bit wide 68008 CPU that dogged the QL. It was attractive to Uncle Clive because it was cheaper, and to Apple team for much the same reason. Apple selected it because it meant that they could use a single 8 bit wide ROM and RAM chip. Back then (and to an extent even now) adding more pins to a chip makes it disproportionately more expensive, so reducing pin count was (is) key and if you wanted a 16 bit wide bus, you put two 8 bit chips in parallel. The 68000 itself was an example of this disproportional expense with its profligate 64 pins. The 68008 had 48 pins which was also pushing it. Fortunately(!), Apple's developers couldn't keep code bloat under control and the firmware grew larger than the a single ROM, at which point redesigning the machine to use the 16 bit wide 68000 was pretty much inevitable. So the Macintosh dodged that bullet otherwise it might have been just a footnote in computer history

[uon]

To be fair, I remember reading dark hints in the documentation at the time that some of the weird stuff in the 68020 (the CALLM/RTM opcodes in particular) were only there because one particular hardware vendor leaned very heavily on Motorola to get them in there, and they were stripped out in the 68030 and subsequent chips.

[liam_on_linux]

Good reply

[pndc]

I slighly misremembered the story I read in Revolution in the Valley, which also turns out to be at http://www.folklore.org/StoryView.py?story=Five_Different_Macs.txt

Rather than selecting the 68008 directly, Burrell designed glue logic for the 68000 that hobbled it down to the same spec as the 68008 to produce the same cost-reduction on memory chips. This work was done in December 1980, whereas the 68008 was released in 1982. It seems likely that Apple would have chosen the 68008 were it available at the time.

Those various emulators are cute, but do rather look like reference designed bodged into cheap Maplin cases, rather than some nice retro hardware that also looks the part.

[pndc]

Also, if you haven't yet discovered http://www.filfre.net/, now is an excellent time to cancel all your appointments for the rest of the day, fetch a case of beer, and have a very long and enjoyable read about the early history of microcomputers.

some addendum

[anonymous]

Hi Liam