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  Which keyboard encoder?
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   Author  Topic: Which keyboard encoder?  (Read 374 times)
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Posts: 116

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Re:Which keyboard encoder?
Reply #9 on: August 08, 2004, 08:37:45 PM
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$40.50 shipped for a custom made kb encoder with 64 simultaneous inputs!  not programmable and actually comes with an AT connector instead of a ps/2 connector, but for 64 inputs, i'm not complaining..
i will post a review once i get it and wire it in..

here is the email i got from him after asking him some pertinent questions about the item:


Unlike other encoders on the market, this board was designed deliberately to
be used in high end Vegas type gambling devices where there is no room for
error.  This encoder does not "ghost" or miss any key stroke.  I wrote the code
on the PIC processor myself and had to include a TON of special routines to
insure that things like this did not occur in order to meet Nevada Gaming
regulations.  This board does NOT use a "keyboard chip" like other encoders do,
instead it has custom software written specifically for use in the gaming

Once you press a key, the encoder will send the make code (scan code) to the
PC only once.  If you hold the key down, it will NOT repeat the key scan code
(typematic mode, like on a regular PC keyboard).  The break code (0xF0 + the
scan code) is sent once the key is released.

Every key can be pressed at the same time without overrunning the keyboard
buffer in the PC.  This is because each input sends the make code once as
opposed to regular keyboard encoders which send the data for each key over and
until it overflows the keyboard buffer.  The order for which the key data is
sent is dependent upon which key is pressed first, and is prioritized
accordingly (this was one of the major requirements of the Nevada Gaming
The priority encoder section of the software will always select keys on CN1
first since in the original application this was designated as the
COIN/BILL/CREDIT/HOPPER input connector.
All other switch inputs have equal scan timing and are encoded in the order
in which they are closed.

On regular PC keyboards, if you press a key and hold it down, then press
another key, the PC will automatically switch from the first key pressed to the
next key pressed.  This is a "typewriter effect" and was intended to improve
typing skills on the keyboard.  This encoder does not do this and will allow as
many key entries one after the other as needed.  For example, if you move the
joystick to the right then press the FIRE button, the encoder will not "cancel"
the right move and only go with the FIRE button (you can try this on a
regular PC keyboard to see this effect).

Some of the encoders on the market are made using the "wedge" technique. 
This technique "wedges" key codes into the keyboard communications lines without

actually interpreting the data on the data and clock lines.  This technique
requires the use of a regular keyboard along with the encoder since the encoder
does not have a command interpreter.  The 64-key encoder is NOT a wedge device
and does contain all the keyboard command interpreters.  This will allow you
to boot your PC with only the encoder connected without getting "hung up" at
"keyboard not found" errors.  The encoder will also respond to all of the PC's
"wait" commands, which are transparent to the user, but are necessary to
prevent untimely data to be sent to the PC from the keyboard and prevent
misinterpreted keystrokes or buffer overflow.

This encoder is not a matrix-driven device.  It has 64 individual inputs
(single line to GROUND).  No special "matrix" wiring required.  Since it does
use a commercial keyboard encoder chip, issues such as blocking and ghosting
have been seriously addressed (as mentioned earlier) due to the absolute
professional original application for the board.

I have 74 of these boards in my stock.  There were about 40,000 of these sold
to various manufacturers OEM in the gaming industry.  This board was
designed, built and sold long before MAME, and now it's a rare find to get hold
of one
of these.  I still design such devices, but only for OEM manufacturers (not
for MAME users).

Spike Tsasmali,
Lupine Systems
WolfmanSpike on Ebay
It's a WOLF Thing!

Return-Path: <******************>
Date: Sun, 1 Aug 2004 20:29:02 -0700
From: ******************
Reply-To: ********************
To: ******************
Subject: Question for item #6111001313 - 64-KEY KEYBOARD ENCODER FOR MAME
X-eBay-MailTracker: 10023.347.0.1

Dear wolfmanspike,

I noticed that you mentioned that one could use this encoder for MAME.  Sine
I am unfamiliar with it and cannot fond much info about it, I have a couple
I understand some encoders still have ghosting/blocking issues like normal
keyboards.  Does this encoder operate by scanning a matrix and would it exhibit
such problems?  When you say the buffer can handle all the keys simultaneously
but the keystroke is only sent once, does the computer still register each
and all individual keystrokes at the same time?  Basically I would like to know
if one could press and hold all 64 keys at the same time and still have them
all register with the computer.
Also, you said no extra keyboard is required.  I only have a simple
understanding of how these things work so is it safe to assume that this will be

recognized as a normal keyboard in any computer that is ps/2 compatible, (with
AT>PS/2 adapter I presume)?

Thank you for your time and understanding.
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