Re: Apple model history?

["Roger Johnstone" <rojaws@es.co.nz>]

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In article <vnuveskej5falaaodnlu16liaa56mchc68@news.newsguy.com>, Paul
Guertin <pg@sff.net> wrote:


>CUTblakeney@home.com (Jeff Blakeney) wrote:
>> The Apple III had little to no effect on the life of the Apple II.
>
>From what I understand, ProDOS is a rewrite of the Apple III operating
>system SOS. Without the III (and therefore without ProDOS), the
>transition from floppies- to HD-based Apple II systems would have been
>more chaotic.
>
>Paul Guertin
>pg@sff.net

Yes, ProDOS is really a subset of SOS. It mainly lacks the more advanced
memory management of SOS. Both share the same disk format and you can even
store both operating systems on the same disk. The boot block will load the
appropriate OS file, either ProDOS or SOS.KERNEL, although I think this dual
boot block was dropped from later ProDOS formatting software.

I do think of the Apple III as a member of the Apple II family. It had the
same processor, similar architecture, same disk drives, same (or similar)
slots and could, with the emulation software loaded, run II+ software. Just
because it had to load software to let it behave as a II means little, a II+
or later can't run Integer BASIC programs from an Apple II unless you first
load the language into the language card.

However it was an evolutionary dead end, it did not spawn any direct
descendants. It would have been nice if the Super II (the IIe) had been a
cheaper version of the III. Instead Apple went back a step to the II+ and
forward in a slightly different direction with the IIe, and even
deliberately held back the IIe to stop it competing with the III. Apparently
this is the reason the original IIe did not have an 80 column display as
standard (it would have only cost a few dollars to have the extra 1KB of
memory and logic needed) and why the memory expansion was originally only to
128KB. It was not until the III was an obvious flop that development
switched back to the II line.


Roger Johnstone, Invercargill, New Zealand
http://homepages.ihug.co.nz/~rojaws
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