TTL circuit boards

The TTL circuits were developed in the USA in the beginning of the 1960s. Tesla started to manufacture them approx. ten years later. They are composed of bipolar transistors and their main disadvantage when compared to newer types of integrated circuits is their high power consumption, because of which the circuits produce a lot of waste heat and are more prone to failures. One circuit could contain a few logic gates, a counter, a code converter etc.. A computer would use hundreds of such boards. Searching for faulty circuits was a daily routine for the maintenance staff. It was necessary to remove the bad circuit without damaging the board. Moreover, Soviet computers had the boards covered in a protective epoxy resin that had to be removed before any repair. The TTL circuits use 5 V supply voltage and the power supply had to provide tens of amperes even for a small part of the whole computer. Despite this, the TTL circuits saved a lot of space and provided much higher speed than the previous computers built of discrete transistors.