Enjoy Experimental Psychology

EXKEY keyboard logic

Although ERTS runs on any standard IBM PC compatible, there might be situations where you want to use external response keys instead of the standard keyboard layout. For integrating external response keys via LPT with ERTS, the EXKEY-logic has been designed.

Hardware-dependent timing accuracy
of different input devices
Input Device	Mean	Variance	Min	Max
PC-keyboard	18.5	5.00	14.3	21.8
Serial Mouse	24.4	0.07	23.9	24.9
Bus Mouse (30Hz)	17.6	76.44	0.8	31.6
PS-2 Mouse	27.1	31.98	14.3	39.7
EXKEY-Logic	0.6	0.01	0.5	0.8

Advantages of external response pads

Using EXKEY your are able to design and use your own response-pads. Subjects will no longer have the feeling to work on a PC. With a dual-monitor configuration you may even separate the computer completely from monitor and response-pad.

Improved accuracy

Unlike PC-keyboard and mouse input, whose hardware transfers responses with delays and/or variance, EXKEY response registration is accurate to the millisecond.

Simultaneous key presses

EXKEY has a build-in key-event buffer and is therefore able to register multiple and even simultaneous responses.

Modular design

EXKEY is a separate device with a documented interface to the response pad. You may connect any kind of electronic open/close switches (keys).

External TTL-trigger

Because EXKEY works with TTL-level, you may connect third party devices which produce TTL-trigger signals.

Easy integration in ERTS

To activate response registration in ERTS you just use the pre-defined key names E1 to E16 within your trial commands.

Software configurable

The 8/16-key modes and the debounce levels are adjustable by ERTS software configuration

The 8-key mode of EXKEY supports registration of press and release events for up to 8 keys.

The 16-key mode of EXKEY supports registration of press events only for up to 16 keys.

Electronic debouncing

The EXKEY microprocessor logic includes debouncing of key contacts. 8 different debounce levels between 1.1 msec and 70 msec.

Parallel port connection

EXKEY is directly connected to one of the parallel port and requires correct interrupt assignments of the parallel port.

DOS keyboard driver

To use EXKEY responses with other DOS-applications a special resident DOS-driver is supplied which translates EXKEY-keys to PC-keyboard keys.

back