Re: 80col Card

[mjmahon@aol.com (Michael J. Mahon)]

Linards Ticmanis wrote:

>AN3 means annunciator 3 and refers to a little used output on the game
>port. The AN outputs were originally designed to put flashing LEDs or
>similar things into paddles, however nobody really though that that
>was a great idea. So Apple recycled AN3 to turn on the double hires
>mode instead.

Actually, the annunciator outputs, AN0-AN3, were almost the _only_
non-dedicated digital outputs from an Apple II, from the very
beginning.  Several devices were made that used the annunciator
outputs to control them and the PB inputs to get data back to the
Apple.  (The STROBE output was also on the game port, but it
only generates a pulse output, and so is a bit harder to use in
bit-banging serial outputs, handshakes, etc.)

In some ways, it's unfortunate that the annunciators were never
used widely enough to keep AN3 from being commandeered to
control DHR mode.  This certainly creates a conflict with other,
prior uses.

The cassette input port was usable, but certainly not at standard
TTL levels and speeds, and the cassette output was also not at
standard TTL levels, since both ports were designed to work with
typical audio cassette recorder headphone outputs and microphone
inputs, respectively.  The speaker digital output could be hacked
with some fooling around, but the Apple provides only the ability
to toggle it, not the ability to set it to a specific state--and most
people wanted to be able to use the speaker, anyway!

-michael

 Email:  mjmahon@aol.com
 Home page:  http://members.aol.com/MJMahon/