Re: Apple Drops Backward Compatibility for Next MacOS

[xyzzy@ponyexpress.net (Edward Franks)]

pubpc1@library.ucla.edu says...
> xyzzy@ponyexpress.net (Edward Franks) wrote:
> >	Also, the original IBM PC had several advantages over the 
> >original Apple ][ and ][+.  For example, a larger memory space and 
> >off-the-shelf component design.
> 
> But: the Apple IIGS has a 16-bit CPU with a 24-bit memory address.
>      the IBM PC/AT has a 16-bit CPU with a 24-bit memory address.
> 
> Both computer can take up to 8MB of memory on a card.  The AT had
> a 640K problem, though.  The GS did not.
> 
> The GS could also use 8MB of ROM for actual ROM and non-volatile
> disk storage (think RAMkeeper).
> 
> Both computers ran at about the same speed (real speed, not MHz).
> 
> 
> 

	But <grin>: I was comparing the Apple ][+ with the orginal IBM 
PC.  I'm talking about 1981 and the start of the IBM PC era and not 
the 1985 era of the IBM PC/AT.  I was trying to show why the IBM PC 
took off better than the existing (in 1981) Apple design.

	To address your points:  The AT only had the '640K problem' when 
the 80286 chip was in real mode.  In protected mode it didn't have 
that problem (it could address up to 16 meg of memory).  The problem 
was that the only two OSes written specifically for the '286 were 
Novell Netware and OS/2 1.x (ugh!).
	Also the IBM PC/AT ran at 6Mhz, and later at 8Mhz.
	One of the bad things about the Intel chips series is the *damn* 
memory segment addressing scheme.  (Luckily the 80386 added a mode 
that had a flat 32-bit memory address space.  Unfortunately this was 
crufted onto the existing modes.  The Intel '86 series CPUs are always 
hampered by their own successes.)

	Too, because the IBM design used a lot of off the shelf 
components it was easy to clone so their developed a lively third 
party industry.
	Anybody remember Apple's response to the Franklin Ace <grin> or 
the the MagicSac (sic) for the Atari ST?

	Too bad Apple didn't introduce the IIgs sooner.  I would have 
liked to see stronger competition for the IBM PCs.

Edward

-- 

Edward Franks
efranks@msn.com
xyzzy@ponyexpress.net

-==(UDIC)==- Fortran Dragon

Microsoft Certified Product Specialist: Windows 3.1

"Ain't I a stinker?" - Bugs Bunny