Hardware techniques for analog processing using the State Systems PDP-8 I/O interface

Methods are described for construction and use of an analog-to-digital (A/D) converter system which is interfaced with a PDP-8/E through the State Systems interface. Eight bits of one input word are used to bring the results of A/D conversion into the accumulator, and four bits of an output word supply convert and channel-select pulses for the A/D converter and associated eight-channel multiplexer. With a Datei ADC-EH8B1 A/D converter, which digitizes a sample in 4.0 microsec, the system software can perform a conversion in 18.8 microsec. Approximate cost of parts for fabricating the hardware is about $120. Examples of software incorporating the A/D capability are presented for a laboratory computer system used to measure operant response force.     

Voltage-controlled oscillators: Inexpensive alternative to analog-to-digital converters

We describe a simple software mimic of an analog-to-digital (A/D) converter that is suitable for most laboratory applications requiring A/D. The routine samples output from a voltage-controlled oscillator that can be built for around $6. Results of proving trials show the output to be linear and sampling rates of up to 50/sec are possible.     

An on-line laboratory in sensation and perception

Three components of a teaching laboratory in perception are described that (1) compare several psychophysical methods for measuring visual illusions, (2) simulate experiments on dark adaptation, and (3) allow participation in auditory demonstrations or experiments. Features of special interest include: interactive use of graphics, software for simulating experiments (such as EXPER SIM, University of Michigan), and use of A/D, D/A, and TTL ports to interface special peripherals.     

Laboratory functions for the Tecmar Lab Tender and IBM PC

A set of assembly language functions has been written to interface laboratory software for the IBM PC to the Tecmar, Inc., Lab Tender circuit board. These functions provide convenient access to the Lab Tender’s parallel ports, timers, A/D converters, and D/A converters from laboratory control programs written in the C language.     

Dynamic Regulation Responding to an External Stimulus: A Differential Equation Model

This study examines the dynamic regulation process responding to an external stimulus. The damped oscillator model has been used to describe this process. However, the model does not allow a nonzero steady state, even though the oscillations may continue and do not necessarily damp toward zero. This study introduces the driven damped oscillator model which has an additional parameter to identify different patterns of the steady state. Three methods, generalized local linear approximation, continuous time structural equation modeling, and analytic solutions of differential equations are provided to estimate model parameters. A simulation study indicates that parameters in the driven damped oscillator model are well recovered. The model is then illustrated using a data set on the daily reports of sales after a sale promotion. Potential applications and possible expansions of this model are also discussed.     

Adding the dimension of color to computer-generated displays

A low-cost system that permits existing computer-generated displays on a black and white CRT display to be reproduced in one of several colors on a color TV receiver is described. A black and white TV camera monitors the computer display, and the camera RF signal is sent to the color TV receiver, which has its three color guns under computer control through an interface unit described herein. In a simple on or off arrangement using three computer output relays, seven distinct and readily identifiable colors are available. With the use of D/A converters, the interface unit is voltage controlled, permitting both faster control and many more hues to be obtained.     

An optically isolated digital interface for the SKED system

A digital interface to support the SKED software system in recent versions of the PDP-8 computer. One printed circuit card of interface logic and optical isolators can be installed in the OMNIBUS to provide 24 input and 36 output lines to external panels containing input simulation switches and input or output indicators.     

A multi-user on-line 8080 microcomputer system

A laboratory control system based upon the Imsai 8080 microcomputer is described. This system is capable of programming separate events in each of five animal operant chambers and recording the resulting behavioral data. The interface between the computer and the chambers is compatible with the 28-V dc nature of these chambers and various peripheral devices, such as cumulative recorders. At present, system software is based on the 8080 assembly language, while the BASIC language is used for data analysis. Cost considerations and comparisons with minicomputers are discussed.     

Realism in energy transition processes: an example from Bohmian quantum mechanics

In this paper we study in details a system of two weakly coupled harmonic oscillators from the point of view of Bohm’s interpretation of quantum mechanics. This system may be viewed as a simple model for the interaction between a photon and a photodetector. We obtain exact solutions for the general case. We then compute approximate solutions for the case where one oscillator is initially in its first excited state (a single photon) reaching the other oscillator in its ground state (the photodetector). The approximate solutions represent the state of both oscillators after the interaction, which is not an eigenstate of the individual hamiltonians for each oscillator, and therefore the energies for each oscillator do not exist in the Copenhagen interpretation of Quantum Mechanics. We use the approximate solutions that we obtained to compute Bohmian trajectories and to study the energy transfer between the oscillators. We conclude that, even using the Bohmian view, the energy of each individual oscillator is not well defined, as the nonlocal quantum potential is not negligible even after the coupling is turned off.     

IDAC computer interfacing for an undergraduate learning laboratory

A hardware and software interface system from International Data and Acquisition and Control, Inc. (IDAC) is reviewed. The IDAC system comes with spreadsheet software compatible for either Macintosh or IBM microcomputers. I prefer to use the IDAC hardware with my own software written in TrueBasic and spreadsheet macros. The entire system is easy to use and is currently in use for our undergraduate Learning Laboratory.     

The labtop Macintosh: An interface and communications software for experiment control of animal learning research

A peripheral interface and communications software are described that allow the Macintosh Plus microcomputer to control experiments in animal learning. A Walter/Palya experiment control board (ECB; Walter & Palya, 1984), connected to the Macintosh by a RS-232 modem cable, operates as the I/O interface. The Hayes-Smartcom II software provides an easily operated communications link through menu and icon commands. Smartcom II allows the Macintosh to transmit experiment control tasks to the ECB and to collect and store obtained data. Network communication over a single RS-232 modem cable is also described.     

Using serial interfaces and the C language for real-time experiments

The use of the serial interface of the IBM PC for timing and stimulus-response signaling is discussed. C language example programs, including two small software utility modules that expedite the programming of real-time experiments using a serial interface, are presented that are compilable with Borland’s Turbo C.     

A distributive method to increase the analogic output (D/A) resolution of a microcomputer

This paper describes a simple and efficient method to increase the D/A output resolution of an 8-bit microcomputer, as exemplified on the Apple II. The “distributive method” can increase the final output resolution up to 32K with two 8-bit analogic channels. A simple interface based on balanced sets of resistors and driver software are described. Some applications are also reported.     

A decentralized computer network for supervision of multiple psychological laboratories

The computer network described was designed to optimize the use of a number of independent minicomputers as a single integrated system for process control of several research laboratories. The implementation of the network required both the development of a special purpose interprocessor interface and the design of a software support system to direct network operations. The network was designed according to the familiar “star” configuration, with the exception that the central computer in the star does not exercise exclusive supervisory control over the system. Rather, each computer on the system “sees” the central computer as a peripheral similar in characteristics to a medium speed I/O device. This design allows each computer to serve not only as a node in the network, but also as an entirely independent process controller.     

Using the IBM-compatible microcomputer’s serial port as an input-output interface

A general purpose input-output interface is an essential tool in many common research situations. This article describes a simple way to set up the IBM-compatible microcomputer’s RS-232 serial port as an interface with up to four inputs and two outputs. First, aspects of the serial port relevant to its use as an input-output interface are discussed. Next, port access commands needed to control output lines and monitor input lines in the appropriate way are described, and examples in the Turbo Pascal 5.0 language are provided. Finally, a schematic diagram and a discussion of a simple circuit to implement the interface are provided.     

A motor timing experiment implemented using a musical instrument digital interface (MIDI) approach

The musical instrument digital interface (MIDI) offers a way for perception and behavior researchers to implement high-quality experiments using inexpensive, commercially available hardware and software. We describe the MIDI and illustrate its applicability to research using a replication of the oscillator signature finding reported recently by Collyer, Broadbent, and Church (1992, 1994).     

Operate your own World-Wide Web server

Although many researchers wishing to use the World-Wide Web for academic purposes rely on centralized Web services, they should be aware that it is neither expensive nor difficult to operate their own server. Doing so provides research-related benefits such as complete control over their host name and documents provided, the guaranteed ability to execute common gateway interface and server-side include programs, immediate access to their collected data, and the ability to better control who participates in their experiments. This paper surveys Web-server software features likely to be of interest to psychologists and conceptually summarizes their operation and use. The basic steps required to set up a Web server on popular microcomputers are reviewed, and security issues concerning Web-server operation are discussed. An accompanying resource Web page can assist users in setting up their own servers.     

A Commodore 64-based interface system for the operant laboratory

A system of interfaces for the Commodore 64 (C-64) microcomputer for use in the operant laboratory is described. This system frees the experimenter from limitations on the number of I/O lines available on the user port of the C-64 and offers the control of operant chambers for a low cost. Subroutines in machine code to control the interfaces, offering millisecond timing of external events, are presented. A sample BASIC program demonstrates how the subroutines are called from BASIC to run a simple discrimination experiment.     

Using open-source solutions to teach computing skills for student research

A course that relies on open-source software for teaching introductory computer programming and Web development to psychology graduate and advanced undergraduate students is described. The rationale, content, learning goals and outcomes of the course are described, along with the specific software used. The advantages of relying on open-source solutions rather than commercial software for implementing such a course are discussed.