4 Feb
2007
4 Feb
'07
12:21 p.m.
The northstar disk controller and many similar ones
required the
processor to suck in each byte anyway, so there was no chance there of
the CPU doing something productive. Now look at the chip count of the
nortstar controller board:
http://www.sol20.org/manuals/nstar_MDS-A-D.pdf
vs. the apple II disk controller (scroll down a bit):
http://www.8bit-museum.de/docs/apple3b.htm#
I am well aware how simple the Disk II card is. That doesn't _ncessarily_
make it a goof design... Personally I'd rahter had had a more complex
controller that didn't use up all the CPU cycles, tht didn't tie me into
using Apple's own drivea (yes there were others later, but not many, and
not at the start), and that was compatible with the rest of the world
By comparison, the apple II controller is brilliant. Yes, there existed
disk controllers with DMA, but those were more complex and cost a whole
lot more in 1977. Besides, the Apple II had a great expansion bus, and
some enterprising company could have plopped a 177x disk controller in
machine at the point it made sense, but apparently it never did as its
Oh they did. I saw am 8" single density disk add-on for the Apple that
used a 1711 (IIRC) on the interface card.
As for the apple II minimalism -- saving a chip here and there --
indeed, it is a toy compared to, say, the the way HP would do it. But
then the HP would have cost 10x as much.
As I've seid so many times before I rarely, if ever, consider the price
when working out if something is the right solution.
Now look at the apple. Yeah, crappy 40x24 text mode,
but they were in
color and, for the time, unheard of bitmapped graphics modes in a
No, the text mode was black and white only. You could flip a soft switch
and get the bytes of screen mmeory (or the top 20 rows of screen memory)
re-interpretted as 2 colour blocks each. What you couldn't do is
arbitrarily mix text and graphis on the screen.
Tony said:
The extra components for both of those functions were minimal. Much is
made of the expansion slots on the Apple ][, but in reality they didn't
really give you anything more than the expansion bus on the TRS-80 Model
1 or PRT. OK, you had to case and power peripherals for those machines,
but that wasn't a mahor problem.
> And another oddiity. The whole design of the
Apple ][ seems to have
> been to save a chip if at all possible
Yes and no. They spent some chips to give the machine great
expandability and color, bitmapped graphics. On the other hand, I admire the design greatly for what it was and for
the time it was
done. The fact the machine came standard with full schematics and a
To be fair, schematics for all the TRS-80 machines and their peripherals
were trivial to obtain, and cheap. I think the technical reference
manuals for the 8 bit machines were only a few pounds each in the UK (I
bought most of them).
-tony