Re: The Apple ][ was cool!

[Leonard Erickson <shadow@krypton.rain.com>]

william strutts wrote:
> 
> "Roy Miller" <millers@inebraska.com> wrote in message
> 3B54AAC2.337E7AE0@inebraska.com">news:3B54AAC2.337E7AE0@inebraska.com...
> >
> <snip>
> > It was the Mac Plus, coupled with a hard drive, and with the LaserWriter
> > AND Adobe Publisher that gave the mac the lead. Not the color Mac II.
> BTW -
> > by that time the PC had VGA, so in some sense the Mac was just catching up
> > with the PC.
> 
> The Mac II was released in March 1987 and I believe the PC standard
> at the time was EGA (4-bit color with 640x350 pixels) versus Mac II
> color (8-bit 640 x 480).

Nope. I've got a programming book copyright 1987 that covers MCGA and
VGA. Those standards came out with the PS/2 series. And the manual for
my Hercules VGA card is copyright 1988. Given that it took a while for
Hercules to copy IBM, I'd say VGA was there in 1987.

> > No, it didn't. And his point was in 1981 the PC could have 640K and the II
> > could only have 64K (or the Kaypro, or the Morrow, or the Compupro, or the
> > TI, or Atari, and so on) Besides, what about 1984 when Macs could only
> have
> > 128K?? And PC came standard with 256? Or in 1985 when the Fat Mac had 512K
> > and PC were standard with 640, and many had EMS?
> 
> The Mac II in March 1987 was upgradeable to 68 meg and the PC had
> how much memory?  16 megs you say.

That's for the AT, which was aroundin 1984 or so. By 87, you are getting
into the 386 systems which could have 64 meg of RAM.

> > The reason for EMM (1987) or EMS (c 1985) was that people wanted to run
> > PC-DOS software, and DOS was limited to 1 meg of memory, and IBM had
> stolen
> > 1/3 of that!
> 
> I believe a lot of that "stolen" memory was mapped to interrupt vectors,
> BIOS ROM's and the like.

Not quite. The Bios "used" the upper 64k, and on real IBM systems, the
64k below that was where ROM BASIC went. Video could take the two pages
pages below that. Which left you the 640k remaining.

00000-9FFFF	RAM
A0000-AFFFF	EGA/VGA video memory
B0000-B1000	MDA video memory
B0000-B7FFF	Hercules page 0 video memory
B8000-BFFFF	Hercules page 1 video Memory
B8000-BFFFF	VGA video Memory
C0000-DFFFF	reserved for addapter card ROMs & RAM
E0000-EFFFF	reserved for ROM BASIC
F0000-FFFFF	system BIOS

You may note that the PC could have both a mono and a CGA video card in
ti at the same time without them interfering with each other. You could
even do that with a Hercules card and an EGA or VGA adapter if you set
the Herc card to not use page 1 of its memory.

> EMM memory was developed because the
> 8088/8086 used a 20 bit address bus that limited the memory to 1 meg.

Yep. Just bank switching.

> The larger address space of the 286 wasn't
> even a consideration at the time.

Also, the 286 design was "frozen" before it became clear that MS-DOS was
going to be important. Which is why it's such a kludge to access RAM
above the 1 meg mark from real mode. 

> > Of course, most people who used ATs used them as very fast PCs crunching
> > numbers, and that 287 chip was very helpful there.
> 
> And how fast was that new fangled AT?  around 6 mhz?  8 mhz? The
> Mac II was 16 mhz and supported a FPU. 

The AT wasn't new then. We had 12 Mhz 286 systems in 84 or 85. 

> You needed that coprocessor
> because the PC was only what 4mhz and the Mac Plus was what
> 8mhz?  How many apps actually used the coprocessor?  Not too many
> unless you did do number crunching.  Most home users wouldn't
> have had the coprocessor or needed it.

Given that his point was that the *ability* of the co-processor to do
number crunching is what *made* the PC a business system rather than a
home system, you comments above rather miss the point.

> Not many have ISA slots these days.  That slot technology is dead.

Alas, there are a *lot* of cards, useful ones, that nobody has bother
creating PCI replacements for. And for that matter, many systems have a
ridiculously *low* number of PCI slots. 

I'm trying to put together a server using a somewhat older motherboard.
And I'm going to have to put an ISA video card in it because it only has
3 PCI slots! I need one for the ethernet card and two for SCSI
controllers...

More modern boards are a bit better but even there they are a bad joke.
For some types of systems you *need* multiple controller  cards and
multiple netowork interface cards. 8 slots was bad enough in the old XT
days. Yet we are going back to the *5* slot days of the original PC.

> Most PC's use PCI based slots even the iMac's.

Yeah, and if you need a spercialized card that isn't *available* except
as an ISA card, or you are trying to put together low end systems for
charity wotk, that's a *liability*, not an asset.
 
-- 
Leonard Erickson (aka shadow{G})
 shadow@krypton.rain.com	<--preferred
leonard@qiclab.scn.rain.com	<--last resort