Printer buffer (2)

PRINTER BUFFER 2 This second and final part of the article details the con- struction of the inter-peripheral buffer. Construction Two printed circuits are required for construction of the printer buffer; one holds command keys, displays, and power supply (Fig. 6), the other holds CPU, memory, and I/O hard- ware (Fig. 5). To begin with, components on the keyboard-display PCB are fitted. Note that electrolytic capacitor Ci and voltage regulator IC26 are fitted well isolated at the PCB track side. The latter part gets hot and must be fitted with a U-shaped twisted vane radiator. The push-button command keys are preferably PCB-mount Digitast types with holes for LED indication (DI. . .D5); see Fig. 6a for the legends with every key. Once this unit has been completed, the presence of correct supply voltage should be tested at appropriate points in the circuit. The main (processor) PCB is a double-sided, through-plated type (Fig. 5), and fitting the components requires no further expla...