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COMPUTER BITS BY RICK WALTERS Test your reaction time using a PC Are you are one of those people who doesn’t believe your reaction time is affected by “a drink or three”. This simple reaction timer will correct that perception once and for all. This reaction timer uses a PC-compatible computer and a simple Basic program to generate an audio cue and/ or a visual prompt via the screen. It then measures the time delay before a key on the computer’s keyboard is pressed. Alternatively, if you connect a switch to the games port and fabricate the equivalent of a brake pedal, you can compare your hand and foot response times. When the software is run, the screen shows all the options that are available – see Fig.2. First, you can elect to have the trigger stimulus as an audible beep, a visual red rectangle or both. Second, either the keyboard (for hand reaction time) or the external switch (for foot reaction time) can be selected. And finally, you can choose between a single reaction time display or have the display show the last five reaction times and their average. The test is started simply be pressing the spacebar. The program now generates the cue (or stimulus) at some random time up to 10 seconds later, after which you press the spacebar again (or the foot switch) as quickly as possible. Your reaction time in milliseconds (a time of 160ms is pretty good) is then dis­played along the bottom of the screen. If you press the spacebar before the stimulus appears, the screen displays the message “No cheating – wait for stimulus”. The program We have elected to write the software in GW-BASIC, as virtually all computers will have a copy supplied with DOS. If you have Qbasic, you may need to allocate the odd line number for subroutines. A fully compiled version of the program is also available. The full listing is almost two pages long and the chances of errors creeping in, if you have to type all the code, are quite high. To overcome this problem, we have listed the minimum code which will allow you to measure your reaction time. This “simple” version provides for keyboard reaction time only and doesn’t display any screen options. The full listing with all the options and the fancy screen is available from SILICON CHIP on a floppy disc, This optional footswitch can be made up from scrap material and plugs into the games port of the computer. February 1996  85 The optional external foot switch is connected to the games port via a 15-pin male D-connector. Note that the Port A and Port B inputs are wired in parallel. This close-up view shows the switch mounting details, Virtually any heavy-duty pushbutton switch with normally closed contacts can be used. Fig.1: connect the leads to the 15-pin D-connector, as shown here. The other end of the cable goes to the switch. along with the compiled version of the program. Minimum version If you want the simple version only, it’s just a matter of typing in the listing published here. If this is the first time you have attempted to enter a Basic program, go back to the DOS prompt (C:>), change to the DOS directory (CD DOS), type GWBASIC and press ENTER. The screen should read something like this: Fig.2: the opening screen when the program is loaded. The test is started by pressing the spacebar and waiting for the stimulus. GW-BASIC 3.23 (C) Copyright Microsoft 1983 1984 (etc) 60300 bytes free OK The message on your machine may vary slightly from that shown above, depending on the particular version, but if GW-BASIC is present you are ready to begin. Start by typing the first line at the cursor; ie, 10 REM REACT1.BAS #1.0 R.W. 20/09/95. At the end of each line 86  Silicon Chip Fig.3: the reaction time is listed immediately below the visual stimulus (if selected). Pressing the Esc key allows you to change the operating setup. press ENTER. Don’t worry if one or two long lines get to the righthand edge of the screen – just keep typing. The line will wrap automatically. When you have finished, or are tired of typing, finish the current line, press ENTER, then type “SAVE C:REACT1”,A then press ENTER, or if using a different drive, substitute that drive letter for C. Note that the “A” suffix saves the file as ASCII text, so that you can read it on a word processor. If this suffix is omitted, the file would be saved in GW-BASIC format which appears on the screen as “garbage”. To run the program while in Basic, type RUN and press enter. If you have made any typing errors, the program will stop and give you a message telling you the line number where the problem occurred. The usual troubles are commas for colons, one pair of quote marks omitted, or a missing bracket. You don’t have to retype the line, just move the cursor along with the right arrow, until you reach the problem, overtype with the correction and press ENTER. You don’t even have to go to the end of the line. To exit from Basic, just type SYSTEM. To run the program at a later time, type GWBASIC REACT1. To quit the program, you just press the END key. Full version As mentioned above, the full version of the software allows you to select the games port, instead of the keyboard, as the stimulus input. To run the compiled (executable) version of the program, type REACTION at the DOS prompt. Alternatively, you can run the program in Basic by typing GWBASIC REACTION. We made a foot pedal using a heavy- duty pushbutton switch with normally-closed (NC) contacts, a right angle bracket, some bolts and nuts, and a couple of pieces of timber which were hinged at one end – see photos. The connection to the games port is made via a 15-pin male “D” connector, with the leads from the NC contacts of the switch wired as shown in Fig.1. Reaction Timer Listing (Simple Version) 10 REM REACT1.BAS #1.0 R.W. 20/09/95 20 GOSUB 1000 ‘Initialise 30 GOSUB 2000 ‘Generate random delay, store time1 40 GOSUB 3000 ‘Wait for keypress, store time2 calc. reaction time 100 GOTO 30 ‘Do it again 999 END 1000 ‘*********** 1010 ‘INITIALISE. 1020 ‘*********** 1030 DEFINT A-Z: DEF FNCENTRE$(M$) = SPACE$((80-LEN(M$))/2) + M$ ‘Centre text 1040 KEY OFF: CLS: SCREEN 9: COLOR 8,3 1050 DEF FNR = CSRLIN: DEF FNC = POS(X): DEF FNCEOL$ = STRING$(79FNC,” “) 1060 DEFSTR E,K: ESC = CHR$(27): ENTER = CHR$(13) 1070 KEYSP = CHR$(32): KEYEND = CHR$(207) 1080 LOCATE 2,25: PRINT “SILICON CHIP REACTION TIMER”; 1099 RETURN 2000 ‘********************** 2010 ‘GENERATE RANDOM DELAY. 2020 ‘********************** 2030 M$ = “Press SPACE-BAR to test, END to finish” 2040 GOSUB 5030 2050 IF K = KEYEND THEN CLS: SYSTEM 2060 IF K < > KEYSP THEN 2040 2070 LOCATE 23,22: PRINT FNCEOL$; 2080 LOCATE 25,1: PRINT FNCEOL$; 2090 RANDOMIZE TIMER: RANDNO = INT((RND*10)/2) + 1 2100 DEF FNSEC = VAL(RIGHT$(TIME$,2)) 2110 NEWSEC = (FNSEC + RANDNO) MOD 60 2120 WHILE FNSEC < NEWSEC: WEND 2130 TIME1# = TIMER: BEEP: RETURN 2199 RETURN 3000 ‘********************** 3010 ‘COMPUTE REACTION TIME. 3020 ‘********************** 3040 K = INPUT$(1) 3050 TIME2# = TIMER 3060 DELAY = CINT((TIME2# - TIME1#) * 1000) ‘milliseconds 3070 LOCATE 23,2: PRINT FNCEOL$; 3080 IF DELAY = 0 THEN LOCATE 23,25: PRINT “No cheating - wait for stimulus!”;: GOTO 3099 3090 LOCATE 23,22: PRINT “Your reaction time was”;DELAY;”milli­seconds”; 3099 RETURN 5000 ‘******************* 5010 ‘CLS & WRITE CENTRE. 5020 ‘******************* 5030 LOCATE 25,1: PRINT FNCEOL$;: LOCATE 25,1 5040 PRINT FNCENTRE$(M$); 5050 K = INKEY$: WHILE K = “”: K = INKEY$: WEND 5060 IF LEN(K) = 2 THEN K = CHR$(ASC(RIGHT$(K,1)) OR &H80) 5099 RETURN Software availability The compiled and Basic listings of the full version of the program (Reaction.exe and Reaction.bas) are available on a floppy disc from Silicon Chip Publications Pty Ltd, PO Box 139, Collaroy 2097. The price is $A7 plus $A3 p&p (Aust., NZ & PNG; $5 p&p elsewhere). Payment may be made by cheque or money order. Alternatively, phone (02) 9979 5644 with your credit card details, or fax the details to (02) 9979 6503. Please indicate the disc size required (either 3.5-inch or a 5.25inch). SC February 1996  87