20 Nov
2009
20 Nov
'09
6:02 p.m.
On 20 Nov 2009 at 8:16, Al Kossow wrote:
Chuck Peddle told me a couple of months ago that the
6502 was never
intended to be a general-purpose microprocessor, it was designed to be
a replacement for hard-wired logic. They had a die size target to hit
to get to the price point they wanted and pulled out things they
thought were unnecessary for its use in that market. In particular,
the length of the registers. I had always wondered why they built a
microprocessor with an 8 bit stack pointer, when the previous 6800
design had 16.
There were variants of the 6502 with mask-programmed ROM on board (I
have a Micropolis floppy drive with one) and 3M Iomat quarter-inch
tape drives had a controller that's not much bigger than a file card
that holds a 6502, EPROM, a little SRAM and a VIA. So the thing
*was* suited to what we'd call microcontroller use.
The $25 price tag may be a red herring. ISTR that MOS started a
price war at Wescon, and the other exhibitors soon followed with
severly reduced pricing. Within one or two years, a Wescon attendee
could go home with not only a sample CPU, but databooks as well, for
free. I used to have a National PACE that I received in that way. I
think my GI CP1600 was a Wescon freebie. The microprocessor war was
heating up fast...
--Chuck