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Microprogramming a minicomputer for fast signal processing
World Abstracts on Microelectronics and Reliability advanced receiver sub-systems are discussed with emphasis on superheterodyne operation.
A survey of published information on universal logic arrays. S. L. HUP,ST. Microelectron. Reliab. 16, 663 (1977). Increasing commercial pressure for (i) standard monolithic circuit layouts and (ii) reduced design times for custom design requirements, is placing increasing emphasis upon the desirability of using standard arrays which may readily be committed for particular requirements. This general survey briefly reviews existing logic concepts in the field of "universal" arrays, many of which have no present (or foreseeable?) commercial viability. However, for completeness, all known general concepts have been surveyed in this document for reference purposes. Note, software-based systems (i.e. microprocessors) are specifically excluded from this survey, being entirely outside our present area of interest One of the fundamental problems of the random-logic area is how best to use the resources of l.s.i, technology but at the same time maintain the flexibility of the single logic gate approach, custom design of special logic requirements and realization in unique monolithic form being in general a completely uneconomic approach for smallquantity requirements. A more viable approach, however, is to consider programmable devices, that is l.s.i, circuits which are general-purpose networks and which finally may be arranged so as to perform specific duties. In this area we will first look at two main contenders, the programmable read-only-memory ("PROM") and the programmable logic array ("PLA'), following which we will consider other theoretical possibilities which have not to date been commercially exploited. Microprocessors heed the call to supervise I/O. G. MARAZAS. Electronics p. 104 (2 February 1978). Applying distributed processing to a minicomputer's input and output chores boosts throughput, cuts costs. Multiprocessor systems. P. HUGHES and T. DOONE. Microeletron. Reliab. 16, 281 (1977). Microprocessor software is becoming more complex, as the one unit is used to handle a multiple of tasks. This leads to considerable overhead in task scheduling software. In addition, communication between separate microprocessor systems also requires extra software. If, however, two or more microprocessors may be attached to the same bus, then many disadvantages of single microprocessor realisations are eliminated. These points, together with practical applications for systems and peripheral controllers are discussed. Take the guesswork out of thick micrnstrip. K. P. SCHWAN. Microwaves p. 184 (December 1977). Don't guess thickness correction when calculating the effective dielectric constant of thick microstrip. Instead, use a simple graph to put Kefl" on the line. 16-bit wave gathering speed. L. ARMSTRONG. Electronics p. 84 (16 February 1978). With users looking for more throughput and greater accuracy, Intel, Zilog, and Motorola are poised to jump in.
The study of microcircuits by transmission electron microsgopy. W. E. HAM, M. S. ABRAHAMS,J. BLANC and C. J. BUIOCCHI. RCA Rev. 38, 351 (September 1977). The use of transmission electron microscope (TEM) methods, especially in cross section, for detailed physical examination of the components of microcircuits is discussed from a device engineer's point of view. Careful attention is given to the type of problem that can best be studied by this
489
method. Details of the required sample preparation process are shown and suggestions are made for ensuring a high probability of success with the samples. Since many readers will be unfamiliar with the mechanisms of TEM image formation, a brief discussion of the features of the sample that cause contrast is included. Specific examples showing use of the method on samples of interest to silicon-on-sapphire technology are presented. These samples show an anomalous thinning effect in the thermal oxide grown on silicon island edges that has not previously been noted. They also clearly demonstrate the capability of seeing layers as thin as 10 A,, as well as the interfaces between almost every material commonly used for the manufacture of microcircuits. Defect distributions within the single-crystal silicon and near the edges of the silicon islands are clearly shown, as is the grain size distribution present in heavily doped polycrystalline silicon used for gate metalization. A possible anomalous boron diffusion phenomenon in polycrystalline silicon due to the grain size distribution is suggested. An example using oxide isolation methods shows that accurate modelling of such processes is possible from the excellent profiles obtained by cross sectional TEM methods.
Dedicated LSI chips aim at communications. R. GUNDLACH. Electronics p. 125 (16 February 1978). The advent of largescale integration is creating a technological revolution in the telecommunications industry. Spurred on by the growing sophistication in today's communications technology and the increased activity in digital switching (itself a result of LSI advances), semiconductor manufacturers are busily developing dedicated-function chips to meet the growing needs of communications companies. Now, after several years' work, a flood of new chips is surfacing-codecs, tone dialers and decoders, fiber-optic transmitter and receiver interface chips, and the like. FETs move up in power and frequency. W. F. ARNOLD. Electronics p. 131 (2 February 1978). V-channel devices rated for up to 100W cw at 175MHz are easy to bias, hard to destroy. Molybdenum-gate RAM is designed for high speed. Electronics p. 3E (16 February 1978). Experimental 16-k device has capacitively coupled sense amp, dummy sense circuit, and two multiplexers. Microprogramming a minicomputer for fast signal processing. TIMOTHY MULROONEY. Electronics p. 136 (16 March 1978). Storing operating-system instructions as well as the fast Fourier transform in a writable control memory boosts throughput by an order of magnitude. An experimental application of microprocessors to railway signalling. A. H. CRrSBENS, M. J. FURNISS and H. A. RYLAND. Electron. Power p. 209 (March 1978). The Research Division of British Rail is engaged in a programme of development which, it is hoped, will result in a microprocessor-based alternative to the electromechanical interlocking equipment used in present-day signalling systems. An alternative system must match the outstanding safety and reliability of present*day signalling technology, which has evolved over a long period of time. Communications chip interfaces with most microprocessors. SAM TRAVIS. Electronics p. 123 (16 March 1978). ACE, a completely bidirectional asynchronous line-control element, also has a priority interrupt scheme and on-chip band-rate generator.
A survey of published information on universal logic arrays. S. L. HUP,ST. Microelectron. Reliab. 16, 663 (1977). Increasing commercial pressure for (i) standard monolithic circuit layouts and (ii) reduced design times for custom design requirements, is placing increasing emphasis upon the desirability of using standard arrays which may readily be committed for particular requirements. This general survey briefly reviews existing logic concepts in the field of "universal" arrays, many of which have no present (or foreseeable?) commercial viability. However, for completeness, all known general concepts have been surveyed in this document for reference purposes. Note, software-based systems (i.e. microprocessors) are specifically excluded from this survey, being entirely outside our present area of interest One of the fundamental problems of the random-logic area is how best to use the resources of l.s.i, technology but at the same time maintain the flexibility of the single logic gate approach, custom design of special logic requirements and realization in unique monolithic form being in general a completely uneconomic approach for smallquantity requirements. A more viable approach, however, is to consider programmable devices, that is l.s.i, circuits which are general-purpose networks and which finally may be arranged so as to perform specific duties. In this area we will first look at two main contenders, the programmable read-only-memory ("PROM") and the programmable logic array ("PLA'), following which we will consider other theoretical possibilities which have not to date been commercially exploited. Microprocessors heed the call to supervise I/O. G. MARAZAS. Electronics p. 104 (2 February 1978). Applying distributed processing to a minicomputer's input and output chores boosts throughput, cuts costs. Multiprocessor systems. P. HUGHES and T. DOONE. Microeletron. Reliab. 16, 281 (1977). Microprocessor software is becoming more complex, as the one unit is used to handle a multiple of tasks. This leads to considerable overhead in task scheduling software. In addition, communication between separate microprocessor systems also requires extra software. If, however, two or more microprocessors may be attached to the same bus, then many disadvantages of single microprocessor realisations are eliminated. These points, together with practical applications for systems and peripheral controllers are discussed. Take the guesswork out of thick micrnstrip. K. P. SCHWAN. Microwaves p. 184 (December 1977). Don't guess thickness correction when calculating the effective dielectric constant of thick microstrip. Instead, use a simple graph to put Kefl" on the line. 16-bit wave gathering speed. L. ARMSTRONG. Electronics p. 84 (16 February 1978). With users looking for more throughput and greater accuracy, Intel, Zilog, and Motorola are poised to jump in.
The study of microcircuits by transmission electron microsgopy. W. E. HAM, M. S. ABRAHAMS,J. BLANC and C. J. BUIOCCHI. RCA Rev. 38, 351 (September 1977). The use of transmission electron microscope (TEM) methods, especially in cross section, for detailed physical examination of the components of microcircuits is discussed from a device engineer's point of view. Careful attention is given to the type of problem that can best be studied by this
489
method. Details of the required sample preparation process are shown and suggestions are made for ensuring a high probability of success with the samples. Since many readers will be unfamiliar with the mechanisms of TEM image formation, a brief discussion of the features of the sample that cause contrast is included. Specific examples showing use of the method on samples of interest to silicon-on-sapphire technology are presented. These samples show an anomalous thinning effect in the thermal oxide grown on silicon island edges that has not previously been noted. They also clearly demonstrate the capability of seeing layers as thin as 10 A,, as well as the interfaces between almost every material commonly used for the manufacture of microcircuits. Defect distributions within the single-crystal silicon and near the edges of the silicon islands are clearly shown, as is the grain size distribution present in heavily doped polycrystalline silicon used for gate metalization. A possible anomalous boron diffusion phenomenon in polycrystalline silicon due to the grain size distribution is suggested. An example using oxide isolation methods shows that accurate modelling of such processes is possible from the excellent profiles obtained by cross sectional TEM methods.
Dedicated LSI chips aim at communications. R. GUNDLACH. Electronics p. 125 (16 February 1978). The advent of largescale integration is creating a technological revolution in the telecommunications industry. Spurred on by the growing sophistication in today's communications technology and the increased activity in digital switching (itself a result of LSI advances), semiconductor manufacturers are busily developing dedicated-function chips to meet the growing needs of communications companies. Now, after several years' work, a flood of new chips is surfacing-codecs, tone dialers and decoders, fiber-optic transmitter and receiver interface chips, and the like. FETs move up in power and frequency. W. F. ARNOLD. Electronics p. 131 (2 February 1978). V-channel devices rated for up to 100W cw at 175MHz are easy to bias, hard to destroy. Molybdenum-gate RAM is designed for high speed. Electronics p. 3E (16 February 1978). Experimental 16-k device has capacitively coupled sense amp, dummy sense circuit, and two multiplexers. Microprogramming a minicomputer for fast signal processing. TIMOTHY MULROONEY. Electronics p. 136 (16 March 1978). Storing operating-system instructions as well as the fast Fourier transform in a writable control memory boosts throughput by an order of magnitude. An experimental application of microprocessors to railway signalling. A. H. CRrSBENS, M. J. FURNISS and H. A. RYLAND. Electron. Power p. 209 (March 1978). The Research Division of British Rail is engaged in a programme of development which, it is hoped, will result in a microprocessor-based alternative to the electromechanical interlocking equipment used in present-day signalling systems. An alternative system must match the outstanding safety and reliability of present*day signalling technology, which has evolved over a long period of time. Communications chip interfaces with most microprocessors. SAM TRAVIS. Electronics p. 123 (16 March 1978). ACE, a completely bidirectional asynchronous line-control element, also has a priority interrupt scheme and on-chip band-rate generator.