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This product is no longer available.

It has been superceeded by our free on-line Keyboard Emulator. To discover the scancodes you need just click the keys and cut and paste the results.

The Keyboard Emulator is here

What does it do?

The device is designed to monitor a PC keyboard circuit and output ASCII codes corresponding to the information being entered at the computer keyboard. It essentially does the reverse operation as our popular 'Mule' interface.

"But", you will say, "this should be a simple thing to do. Why should a special interface be needed?"

You're right, this should be a simple thing to do, unfortunately it isn't!

The PC uses a complicated system to pass keyboard information. The system is based on 'scancodes'. Scancodes identify only the position of the key on the keyboard (a key number) they do not identify directly which character is being sent to the screen.

For example the 'A' key always sends the same scancode regardless of the state of the shift key or the current caps lock state. The Shift key and the caps lock key both send their own scancodes and a different scancode is sent whenever a key is released. The PC keeps a record of which key or keys is currently or has recently been pressed and then calculates which character the user requires. To make things even more difficult the PC sends scancodes back to the keyboard telling it to switch 'on' or 'off' the 'Lock' indicator lamps and for some other housekeeping tasks.

The Shadow Mule cuts through all this complexity and outputs a clean simple ASCII data stream representing the characters the user is entering at the keyboard. You can forget everything you ever heard about scancodes. The output from the Shadow Mule is just like you imagined it would have been before IBM invented scancodes.

The Shadow Mule can be operated in a number of different modes depending on whether you need to know just the regular ASCII characters or when the non ASCII keys like Function or Cursor control keys are pressed.

It can even give you a raw scancode output and tell you whether the scancode originated from the keyboard or the PC. This is particularly useful for trouble-shooting difficult to find hardware problems with the keyboard circuit.

But we believe most busy engineers want to keep it simple and that's how most will use the Shadow Mule. All the scancode information can be output for analysis and special purposes if you really need it - most of the time you won't need it or even be aware of it.

What can it be used for?

The Shadow mule can be used for a number of different monitoring, control and robotic applications...

The Shadow Mule is simply inserted into the keyboard circuit. It requires very little power which it draws from the PC. The Shadow Mule does not interfere with the keyboard circuit at all. It simply monitors activity and reports what it finds. Once fitted it can be forgotten. It comes with all cabling necessary for to suit both regular keyboards fitted with 5 pin DIN connectors and PS2 keyboards fitted with 6 pin mini DIN connectors.

The Shadow Mule operates with virtually all (IBM compatible) PCs manufactured in the past 10 years which use AT scancodes. In other words PCs with 286 and earlier processors will probably not be suitable. Neither will Macs or Dumb Terminals made by Wyse (or others) with keyboards described as IBM PC compatible.

Further detailed technical information about the Shadow Mule and how it works can be found in the Online Shadow Mule User Manual.

Email Questions about the Shadow Mule to Technical Support


Supplied complete with everything you need...

Related Pages

Keyboard Scancode tables

'The Mule' Interface

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