Precision clock for PCs

Build this small add-on unit and put an end to the (often gross) inaccuracy of the real-time clock that ticks in your PC. Complete with a software driver, the precision clock synchronizes your PC to DCF77, a time standard transmitter operating in the long-wave band.

Many games, utilities and other application software for the Atari ST computer are supplied as ROM / EPROM modules ('cartridges') of which, unfortunately, only one at a time can be connected to the computer. The circuit described here over comes this undoubted short coming of an otherwise excellent computer. It allows up to five ROMlEPROM modules to be connected at the same time, and to be selected by software.

Software to control the GAL programmer is now also available for the Amiga series of computers. The Amiga software consists of two programs, AmiGAL and AmiBURN, with associated (extensive) documentation files that can be printed from disk. The disk also contains an installation instruction file.

This month we close the article with a description of the control software developed for the DiAV system. Also, we help you to test the main unit, and show you how to make a professionally finished infra-red remote control transmitter.

The data generator offers a simple means of testing a circuit.There is no need of software for some microprocessor and all the components are readily available. The design is based on the timing of a Type 5DA3002 circuit.

The computers in Commodore's Amiga series are widely praised for their powerful sound and graphics. Not surprisingly, some bulletin boards abound with graphics files and/or tracker modules that have been produced by this popular computer. The sound sampier described in this article gives all Amiga users the possibility to start digitizing sound at a small outlay.

No PC interface has attracted more attention in the electronics press, and caused hotter debates, than the RS-232 interface. It is unfortunate but true that both hardware and software appear to be open to different interpretations when it comes to connecting RS-232 devices like printers, plotters, mice and modems. The tester described here is a handy tool to help you locate possible hardware errors, when hooking up a new RS-232 peripheral is not going as smoothly as you would have hoped.

Following last month's description of the system structure and the circuit diagram, this second and last instalment looks at building and testing the card.

Designers of digital equipment are fully aware of the difficulties of testing their designs to confirm that the logic of the design works according to plan. Even more difficult, rather as with computer programs, is the ability to conduet the infinite number of tests to prove that there are no bugs or glitches in the design some of which may only appear when an unusual set of conditions exists, or perhaps only once every billion clock pulses or so.

This article describes hardware and software that together torm a powerful development system tor the popular 8751 microcontroller trom Intel.