Retrotechtacular: AM Radios, Core Memory, And Color TV, What Was Hot In Chips In ’73


As part of writing tech stories such as those we feature here at Hackaday, there is a huge amount of research to be done.  We trawl through pages and pages of obscure blogs, videos, and data sheets. Sometimes we turn up resources interesting enough that we file them away, convinced that they contain the nucleus of another story at some point in the future.

Today’s topic of entertainment is just such a resource, courtesy of the Internet Archive. It’s not a video as we’d often provide you in a Retrotechtacular piece, instead it’s the February 1973 edition of the Fairchild Semiconductor Linear Integrated Circuits Catalog. Books like this one that could be had from company sales representatives were highly prized in the days before universal Internet access to data sheets, and the ink-on-paper datasheets within it provide a fascinating snapshot of the integrated electronics industry as it was 45 years ago.

The first obvious difference between then and now is one of scale, this is a single volume containing Fairchild’s entire range. At 548 pages it wouldn’t have been a slim volume by any means, but given that Fairchild were at the time one of the big players in the field it is unimaginable that the entire range of a 2018 equivalent manufacturer could be contained in the same way. Given that the integrated circuit was at the time an invention barely 15 years old, we are looking at an industry still in relative infancy.

The catalog has a series of sections with familiar headings: Operational amplifiers, comparators, voltage regulators, computer/interface, consumer, and transistor/diode arrays with analog switches. Any modern catalog will have similar headings, and there are even a few devices you will find have survived the decades. The μA741 op-amp (page 64) from its original manufacturer has not yet become a commodity product here, and it sits alongside familiar devices such as the μA7800 series (page 201) or μA723 (page 194) regulators.


The uA702 circuit has a real simplicity to it.

The op-amp chapter reads almost as a potted history of the development of these components as integrated circuits from Bob Widlar’s original μA702 (Page20, labeled as a “DC amplifier” here) through its improved siblings to the familiar frequency-compensated μA741 that we’ve already mentioned, and thence into the realm of FET input devices. Op-amps are a field that is still developing, but in these pages and over just that decade’s development we see their genesis.

Power supply regulators in 1973 are exclusively linear, in sharp contrast to the array of switching regulators that would grace a similar chapter today. This section shows a field in its relative infancy, in which a 3-terminal μA7800 series regulator was still a big deal, and in which the μA723’s switching application circuit is an oddity rather than its primary application. One surprise comes from the negative versions of the three-terminal regulators, what we would know as a 7900-series chip is instead a 78N00-series (page 238). Did 7900-series chips debut from a rival manufacturer? Perhaps readers would like to speculate in the comments.

The computer interface chapter is a selection of line drivers, RS232 interfaces, display drivers, and A to D converters. Some of these functions are still available in today’s catalogues, but it’s fair to say that computer interfacing has moved on since the 1970s. An archaic set of items though are the core memory drivers and sense amplifiers starting with the 75325 on page 318. Core memory was out-of-date by 1973 and is now something of a curio, so these data sheets make particularly interesting reading for the student of computing hardware history.


A complete NTSC color decoder in 3 chips. When you could still buy sets doing this with discrete components, this was a very big deal indeed.

The last-but-one chapter shows us 1973 at its finest, or perhaps some of the 1973 those of us who were alive at the time might remember. The functions in Fairchild’s consumer product line are entirely analogue, and reflect the state-of-the-art in what the well-to-do family might have wished for in their living room or car.

A CRT color TV and a stereo FM radio were both big-ticket items in the early 1970s, and though home computers had arrived by the end of the decade they would remain supreme in the world of home entertainment for many years to come. Thus we have entire chipsets for the small-signal and color decoder sections of NTSC (shown here from page 458) and PAL TVs, triple video op-amps for color CRT drivers, stereo multiplex decoders both analog and PLL, and entire AM radios on a chip, but not a digital IC to be seen. Uniquely among all the chapters in the book this one has no survivors into the present day, even those chips that might still find a use have been superceded many times over.

Finally, we’re on familiar ground with a chapter of transistor arrays, diode arrays, and a single analog switch. The 3046 transistor array (page 499) should be a familiar part as it is still available, and it serves to highlight something else about the Fairchild range. In most of the chapters are these parts with just a number and no letters, these are Fairchild’s take on a competitor’s device. Thus for example the 3046 is RCA’s CA3046, and in the op-amp chapter the 301 is National Semiconductor’s LM301. Given that the 301 was the work of [Bob Widlar] when he left Fairchild for National, there must have been some internal politics over the cloning of that particular part.

In 1973 many pieces of electronics were entirely made from discrete components and it was still possible to buy consumer electronic devices containing germanium transistors or even tubes, so this catalog gives us the state of the art in linear circuitry rather than a universal picture. It makes an interesting read for its insights into archaic technologies as well as for its look at some of the semiconductor industry’s component survivors, and it would still find a place on the shelves of a Hackaday writer, were she to find a physical copy. We have come a long way since 1973, but there is still value sometimes in looking back.



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