3 Feb
2007
3 Feb
'07
10:28 p.m.
On 3 Feb 2007 at 22:56, Jim Battle wrote:
Let's look at contemporaries (1977 micros). The
Sol-20 had 64x16
text, and unless you polled the hblank signal and limited yourself to
poking one character per 50 uS, you'd get snow on the screen. There
were others that had the snow problem as well (eg, exidy sorcerer).
The TRS-80 didn't have the snow problem, but it too had a 64x16 text
display. The PET (which I never used) also had character graphics of
the most pathetic sort.
The DIsk II didn't come out until 78. The 1977 Apple had only a
casette interface. Remember that OSI (from around the same time)
used a 6850 UART for the same purpose, yet OSI didn't get any acclaim
for the "genius" of the controller. Instead, it got slammed for the
incompatibility of the floppies.
A major part of Apple lore, it seems to me, is the mystique.
Cheers,
Chuck
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
microcomputer. By running the DRAM at 2x the CPU cycle time and locking
it to the video rate, all graphics could be written real-time with no
snow and no wait-states. Other than DRAM and the CPU, all cheapo TTL.
Tony said:
> 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,
wherever Woz could save a chip (or ten), even if it meant an oddball
mapping of memory to screen, was done to save cost and keep the board
size down. It is fantasy to think that cost wasn't one of the most
important factors in a successful home computer.
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
commented disassembly of the ROM should not go unappreciated with this
group. The machine has character, the good kind, in spades.