Software synchronizing of video displays and Z-80 processing in the Model III TRS-80

Dlhopolsky, Joseph G.

doi:10.3758/bf03203419

Cited by 10 publications

(8 citation statements)

References 4 publications

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“…DELAY is used to delay the start of MSEC LATENCY TIMER until the CRT's electron beam is about to scan the stimulus display line. Lines 240-280 revector the real-time clock interrupt, which operates off the video vertical synch pulse (Dlhopolsky, 1982). The next interrupt to occur starts the execution of the main portion of the routine at line 350.…”

Section: A Two-field Tachistoscopementioning

confidence: 99%

“…As a result, the latency timer begins within microseconds of the actual stimulus appearance. A more detailed description of this video synchronization technique appears in Dlhopolsky (1982).…”

Section: A Two-field Tachistoscopementioning

confidence: 99%

“…Because of this, it is recommended that all trial events be operated throughout by machine language. Moreover, it is often desirable to synchronize stimulus displays with the CRT's electron beam (Dlhopolsky, 1982), which requires a machine language routine. Thus, all things considered, video synchronization, stimulus display, interval timing, and response recording should all be under machine language control.…”

Section: J=peek(andhfff A)+256*peek(andhfffb) 110 J = 2000-j:' 2000 Is Thmentioning

confidence: 99%

“…the appearance of stimulus data in video memory with its appearance on the screen (Dlhopolsky, 1982;lincoln & Lane, 1980;Merikle, Cheesman, & Bray, 1982;Reed, 1979). Furthermore, when response latency is also recorded, the timing loop must include a command monitoring the subject's response, be it a keyboard manipulation or an external input to one of the computer's I/O ports.…”

mentioning

confidence: 99%

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Machine language millisecond timers for the Z-80 microprocessor

Dlhopolsky

1983

Behavior Research Methods & Instrumentation

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Section: A Two-field Tachistoscopementioning

confidence: 99%

Section: A Two-field Tachistoscopementioning

confidence: 99%

Section: J=peek(andhfff A)+256*peek(andhfffb) 110 J = 2000-j:' 2000 Is Thmentioning

confidence: 99%

mentioning

confidence: 99%

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Machine language millisecond timers for the Z-80 microprocessor

Dlhopolsky

1983

Behavior Research Methods & Instrumentation

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“…The decoupling of the program and display processes was recognized at an early point in the use of microcomputers for tachistoscopic laboratory applications (Dlhopolsky, 1982;Grice, 1981;Lincoln & Lane, 1980;Merikle, Cheesman, & Bray, 1982;Reed, 1979). Past solutions involved either hardware or software techniques in the Apple II and Commodore PET, and Models I and ill of the TRS-80.…”

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confidence: 99%

Synchronizing stimulus displays with millisecond timer software for the IBM PC

Dlhopolsky

1989

Behavior Research Methods, Instruments, & Computers

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A C language technique for synchronizing millisecond timer software to the appearance of the stimulus on the IBM PC's video monitor is described. Tachistoscopic programs that use the technique can correct the mean 8.3-msec bias normally found in reported response latencies and reduce the associated error variance.Researchers considering the use of the IBM PC for tachistoscopic applications should know that the appearance of a stimulus on the video monitor is controlled by two asynchronous processes: the computer program and the video display circuitry. The program executes instructions that result in the storage of character data (or pixel images) in random access memory (RAM) that is dedicated to the video display. The display processing hardware recurrently reads video RAM and controls the intensity of the monitor's electron beam as it "draws" images. The result: the computer program-which also initiates the timing of response latencies-normally does not know the precise moment at which the display process causes the stimulus to appear on the screen.The decoupling of the program and video processes has a number of effects of interest to researchers who require precise control over brief stimulus displays and millisecond interval timing. As the vertical dimension of the stimulus increases, it becomes more likely that the stimulus will be drawn on the screen in parts. For example, the electron beam might be aimed at the middle of the screen when the program transfers the stimulus data to video RAM. The bottom portion of the stimulus would then appear first, followed by an interval during which the electron beam would be scanning the bottom and then the top of the screen (both areas presumably empty of stimulus parts). Finally, the top portion of the stimulus would appear. The interval between the appearance of first-and last-drawn portions would be 16.7 msec (assuming a monitor with a 6O-Hz refresh frequency).The situation for response latencies produces both biased results and increased error variance. If the program starts a millisecond timer following the execution of the commands to display the stimulus, the timer will have been running an average of 8.3 msec before the stimulus Correspondence may be addressed to Joseph G.

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Perception Time Measured with the Slope-Transition Paradigm (STP): Category, Set Size, and Task Manipulations

et al. 2005

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A perception time measure was obtained with the 'slope-transition paradigm' (STP), which is described in detail. In two experiments with the paradigm, participants viewed two sequential data frames, each presented for a wide range of durations. They made a binary response based on combined information from the two frames. The results showed piecewise linear response-time versus frame-duration functions with a slope-0 branch at short durations, followed by a slope-1 branch. The duration where the two branches met (the slope transition) was interpreted as the end of the perception of frame 1. For longer durations, the participant had completed the perception of frame 1 and was forced to waste time waiting for data from frame 2. In experiment 1, an odd-digit enumeration task was used, and set size and distractor category (even digits versus consonants) were varied. In experiment 2, a same/different task with digits was used and the type of judgment (literal versus parity) was varied. Perception time increased with set size. Distractor category and judgment type affected post-perceptual processes. The perception time measure of the STP is considered in relation to the attentional blink, repetition blindness, and object files.

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Software synchronizing of video displays and Z-80 processing in the Model III TRS-80

Cited by 10 publications

References 4 publications

Machine language millisecond timers for the Z-80 microprocessor

Machine language millisecond timers for the Z-80 microprocessor

Synchronizing stimulus displays with millisecond timer software for the IBM PC

Perception Time Measured with the Slope-Transition Paradigm (STP): Category, Set Size, and Task Manipulations

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