C integral types [was Re: Semi-OT: Why Kids Can't use Computers] (fwd)

[D. Hugh Redelmeier]

| From: William Park <opengeometry-FFYn/CNdgSA at public.gmane.org>

| On Fri, Aug 16, 2013 at 06:06:38PM -0400, Lennart Sorensen wrote:

| > Yeah, it's amazing we are stuck with the legacy of so many bad decisions.
| > 
| > IBM considered the m68k, but decided that the board would cost to much
| > compared to the 8088 (even the 8086 requiring a 16bit bus was considered
| > to cost too much).  Of course the Mac, Amiga and Atari ST all went
| > on to use the m68k, as did the Sun 3, HP 7xx, Apollo, and NeXT among
| > many others.  Amazing how a CPU that everyone used lost out to the one
| > only one type of machine used.

To give it credit, the 8086 came out LONG before the 68000.
Apparently it was good enough.

(Don't believe published "dates of introduction".  
<https://en.wikipedia.org/wiki/Transistor_count> says that the 68000 was 
introduced in 1979 but I got an XC68000 (engineering sample, before normal 
production) in 1981.)

As a compiler writer, I didn't think generating code for any 8-bit 
processor made sense -- hand-coded assembly code would be too much better.  
The 6809 was getting there.

The 8086 was good enough to compile code for.  At least in the small
model, all that was needed initially.

The 68k was much more expensive.  In fact the package was astonishing
when it came out: I'd never had a 64-pin DIP before.

The next generation was interesting too.  The 80286 had a decent on-board 
MMU (no paging); almost no sytem ended up using that during the chip's 
useful lifetime.  The 68020 (later) had a not-so-great optional separate 
MMU chip so Sun built their own.

When I bought my Atari ST (very new at the time) with a 68000 CPU, I 
almost bought a cheap Taiwanese clone PC/AT instead (also new at the time) 
with a i80286.  The MMU on the AT's 286 meant Unix could run reasonably on 
it whereas the ST had no MMU.  The PC came with a hard drive for about the 
same price as the ST with only floppies.

(The ST did have circuitry called an MMU.  It did nothing like what we 
think of as an MMU, but it did one great thing: it prevented user 
programs storing into 0, thus catching most writes through NULL pointers.)

So: dirt cheap mass-market 286 systems came out about the same time as
cheap 68000 systems.  Comparing 8086 with 68000 isn't completely fair
due to the different introduction dates.

| Yeah, this is where "Beta" won (vs. VHS). :-)

?

Intel's instruction set architecture was inferior to Motorola's.  Not
so clear about everything else, which does tend to matter.  The 386
instruction set was as clean as the 68k.

Beta was supposed to be better than VHS.  As an early adopter of VHS, I
don't actually agree.  My first VCR (~$1400!) could record 6 hours,
had extra heads with a different gap to record that in reasonable
quality, and recorded HiFi audio in the helically scanned signal.
Beta couldn't touch that at the time.  Of course each format
leap-frogged, until Beta stopped bothering.
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