4 Feb
2007
4 Feb
'07
3:28 a.m.
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.
Wouldn't the difference be that the more complex cassette interfaces are
less prone to error? The MITS documentation says that the 680-KCACR
accepts a -20 to +20 % speed variance.
I have played basic into my Altair with two recordings. One of them is 10
minutes long and the other is 13 minutes. Neither recording is demodulated
at 300bps. Both of them load with no checksum errors, the recordings are
from the same tape on two different tape players with
different playback
speeds.
I would be interested to find out if the Apple II was as good. Does the
Apple II use the same or a similar circuit as the Apple 1? Woz has a
schematic for it in the Wonderbook or whatever that big PDF is
called. Pretty much a comparator or opamp connected to a data line for
demodulation.
Grant