Original articles on the Beta appeared in 1984 in the popular-scientific magazine Kijk (which means ‘Look’ or ‘Watch’).
Design and articles by Steven Bolt, Pitronics. All rights reserved, this publication by permission of Mr Bolt.
The Beta computer is a small but fully functional 6502 system. Ideal for controlling applications! The base, called ‘controller’, is a PCB with 6502 cpu, a 6532 RIOT and a 2716 EPROM. A really minimal 6502 system with lots of I/O and a minimal IC count. This standard controller is meant to be inserted in a PCB called ‘terminal’ on which specific hardware can be placed, depending on the application.
Two ‘terminals’ have been described in the original articles, one acting as a development system, with KIM-1 like seven segment LED display, hex keyboard and an EPROM programmer. The second ‘terminal is a smaller board with a relay to switch a load and temperature sensor and also a keyboard and LED display. Besides the original articles, scanned and in dutch, the most relevant information of this system is shown in english, including source of the monitor.
- Dutch article series 1984
- Original source, scanned from paper
- Beta Monitor, source, and binary
- Article 1984 hires scan, tnx G. de Bouter
The Robot Arm
Here you can see the Beta computer put to work. Controlling a robot arm is a job a 6502 based machine like the Beta can do very well.
A minimal system, 6502, 6532 RIOT for I/O, timer and 128 byte RAM (zero page, stack, program memory, mapped all from address 0000) and a 2716 EPROM for a control program like the Beta monitor.
As you can see, a minimal system. To make it as universal as possible this controller needs an external clock, a Reset circuit and a power supply to start.
Terminal for development
The development system for the beta monitor has a hexadecimal keyboard , six hex digit LED displays, keys for A(ddress), D(ata), G(o)and a Reset key.
After resetting the Beta with the Reset key and pressing G the Beta monitor is atarted. With the A and D keys (with LEDs showing the current A or D choice) and the hexadecimal keyboard, addresss and data can be selected and dsiplayed and data stored. With the G(o) key a program at the selected address is started.
|The memory map||6532 RIOT|
|0000||monitorvariables||Data Register A||0080|
|0007||vectors (IRQ, NMI)||Data Direction Register A||0081|
|000B||variables EPROM, BRK||Data Direction Register B||0082|
|0015||free RAM||Data Direction Register B||0083|
|0078||stack||Port A7 rise/fall detection|
|0080||I/O, timer 6532||Port A7 interrupt enabled on rise/fall||0087/0086|
|009F||Port A7 interrupt disabled on rise/fall||0085/0084|
|FB7D||24 hour clock/alarm||1024||009F/0097|
Start addresses of subprograms
|EPROM empty check||FAE3|
|24 hour clock/alarm||FBEF|
Source and binary of the Beta monitor: Beta Monitor, source, and binary
The Robot Arm
Terminal as Temperature controller
This variant of the terminal shows how the Beta controller can be used to measure temperature and switch a device like a central heating system.
The difference with the development system are no EPROM programmer, a temperature controlled oscillator connected to PA7 and a relay. Also no crystal based clock, and a 50 HZ line frquency based interrupt at the NMI input.