On Mon, 14 Sep 1998, Tony Duell wrote:
> There are 2 unused positions on this board. One is marked S2, and seems
> to be for a DPDT switch. There are X-pads to cut (I guess) when you
> install this switch.
I found the perfect book to answer this question over the weekend. Its
called _The Apple II Circuit Description_ by Winston D. Gayler. It
includes in-depth technical descriptions of the Apple II and detailed
fold-out schematics of every major subsystem in the Apple II, including
the CPU, the bus pinouts, the keyboard, etc.
This should answer your question:
"Quad-mode operation--B6 is a quad-mode encoder. This means each key can
generate up to four different characters as a function of the SHIFT and
CTRL keys.
"Lowercase--there are two bow ties on the board with the ICs [the encoder
board]. They may be cut as a user option. The circuit is then restored
by adding switch S2. In the normal position of S2, the circuit functions
as previously described [ie. normal Apple II keyboard encoding]. When S2
is operated, output bits 9 and 8 are substituted for bits 5 and 6.
Encoder B6 has been programmed with ASCII lowercase letters. This
substitution of bits will make the lowercase letters available.
Lowercase operation is as follows: with the shift key not depressed,
pressing any letter key will output lowercase. With the shift key
pressed, pressing any letter key will output uppercase.
Numeric pad--As a user option, a nine-pin connector may be installed on
the keyboard at J2. Then J2 can be extended to a numeric pad."
Let me know if you have any more specific questions. This book is
excellent.
Sam Alternate e-mail: dastar_at_siconic.com
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Received on Mon Sep 14 1998 - 18:10:32 BST