Re: [NTLK] Keyboards: What is the difference between ASCII and Scan mode

From: Daniel Padilla (dproldan_at_telefonica.net)
Date: Wed Mar 23 2005 - 15:52:23 PST


    It could be two things:

1.-
    Scan mode refers to the situation where the keyboard sends the position
of a pressed or released key as column/row data, usually one byte per key,
where some bits are the row, some other are the column and one for pressed
vs depressed. This data has to be translated in the computer to meaningful
letters or characters, typematic rate, etc.

    ASCII mode means that the keyboard is sending the ASCII data itself, the
computer only has to paste that data in the receiving application. The
keyboard acts as a serial terminal.

    I would say that the difference doesn't depend on the computer, but in
the keyboard. The newton keyboard is sending bytes, not characters, so both
NOS1 and NOS2 keyboard applications use some kind of scan mode to different
degrees.

    The inPath barcode reader sends ASCII data, and the driver just pastes
what it receives.
    The StowAway keyboard send bytes, and the driver translates the bytes
into letters, in a very basic scan mode.

or
2.-
    Scan mode is when a keyboard only consists of columns and rows, and the
computer is the one that has to scan that matrix every x milliseconds and
retrieve which key has been pressed.

    ASCII mode is when the keyboard has a controller that scans the matrix
and sends the data bytes or ascii data by itself over a serial line to the
computer.

HTH
Daniel

----- Original Message -----
From: "Frank Gruendel" <newtontalk_at_pda-soft.de>
To: <newtontalk_at_newtontalk.net>
Sent: Wednesday, March 23, 2005 7:12 PM
Subject: [NTLK] Keyboards: What is the difference between ASCII and Scan
mode

Yes, this is Newton-related. Wait and see. Could some
kind soul please enlighten me on what is the difference
between scan mode and ASCII mode as far as keyboards are
concerned? It seems that as of OS 2.0 the Newtons can
handle scan mode, earlier models can only handly ASCII
mode.
Since I've subscribed to the digest version of NewtonTalk,
I would appreciate your cc'ing your answer to my address.

Thanks in advance

Frank

-- Newton software and hardware at http://www.pda-soft.de

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This is the NewtonTalk list - http://www.newtontalk.net/ for all inquiries
Official Newton FAQ: http://www.chuma.org/newton/faq/
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