Electronic Design



The field of analog-to-digital converters (ADCs) has seen numerous advances over the past couple of years, particularly in 12-bit devices. For example, you can get 12-bit ADCs that sample at 30 MHz, 12-bit sampling ADCs in 8-pin miniDIPs, or even 12-bit ADCs for under $10 each in quantity. Now, for the first time, 12-bit ADCs that are 12-bit accurate over their operating-temperature range are available. And the world's most-accurate IC voltage reference (over temperature) comes for free on the same chip. Based on switched-capacitor technology, Crystal Semiconductor's new successive-approximation IC ADCs... grab a signal in 0.5 µs maximum and perform a 12-bit-accurate conversion in just 2 µs maximum, for a throughput rate of 400 kHz.

Unlike other similar devices, the conversions of the new ADCs are not only 12-bit accurate at 25°C without any trimming, but they're also guaranteed to be 12-bit, ±1-least-significant-bit accurate over the ADC's complete operating-temperature range.... Put another way, these converters give you 12-bit absolute accuracy or total unadjusted error (TUE) over temperature. (Cover Feature, p. 55)


Trying to capture a major portion of the projected $1.5-billion home computing market, Radio Shack has just introduced a low-cost Z80-based home computer. The TRS-80, which is the second system aimed at home computing, includes an ASCII keyboard, a video display, and a cassette recorder for bulk storage.

The whole system will cost $599.95. This price includes the Z80 CPU, 4 k of RAM, and 4 k of ROM—which contains Basic....

The computer can be internally expanded to 16 k of RAM—which costs $289—and 12 k of ROM. The additional ROM will be used to hold extended Basic and an assembler editor....

The TRS-80 has no standard interface. Instead, a 40-line bus in the Radio Shack unit is brought out to the rear of the computer on pc board fingers, which mate with an edge detector.

Other features of the TRS-80 computer include a 16-line CRT display with 64 characters per line and a computer-controlled cassette-storage system. The format of the CRT display can be changed to display 32 characters per line by altering the machine language program that controls the output. (News Scope, p. 19)


AUGUST 30, 1962
An electrocardiogram (EKG) recently was transmitted from Africa to the United States via a standard telephone hook-up. This was said to be the first such transmission.

The heart of the system was a device known as the Sonlink model TRM-20, manufactured by Mnemotron Corp. of Pearl River, N.Y. The TRM-20 requires no electrical connection or other modification of the telephone equipment.

The EKG signal... is detected by a standard electrocardiograph and coupled to the Sonlink, which converts it into a frequency-modulated digital signal. This representation of the original EKG signal may now be recorded on magnetic tape, transmitted to a remote point, or both.

Although the Sonlink was used to transmit an EKG, it can handle any data with a frequency range of 0 to 100 cps. The TRM-20 can be used on any telephone line that has not more than 30-db insertion loss. A 100-mv signal is required for full scale deflection. (News, p. 23)

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