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A digital signal generator
Hardware AIIman, G and Insley, M 'Selecting and implementing semicustom LSI' Electron. Prod. Des. Vol 2 No 10 (October 1981) pp 6 5 - 6 9 Semicustom uncommitted logic array circuits allow the system designer to realize the advantages of large scale integration without having to master the intricacies of circuit design. The price of custom or semicustom parts in appropriate volumes may be less than the price of MSI/SSI parts they replace, but this is not always the case. Much more significant is the reduction in system cost through smaller printed circuits boards, lower assembly and rework costs, system cooling, housing and power supplies. Board testing becomes easier, system reliability is improved and if failures occur, troubleshooting is less difficult and maintenance costs are reduced. A range of issues in the design of products using gate arrays is discussed in this article with particular reference to CMOS for TTL designers.
Hall, A 'A Z80 serial interface using DMA' Electron. Prod. Des. Vol 2 No 10 (October 1981 ) pp 4 3 - 4 6 The transfer of ASCII characters over a serial communications link is normally achieved either by having the serial interface interrupt the CPU when it needs another character or by having the CPU continuously poll the interface, waiting for it to indicate that it is ready to receive another character. The first of these two operations is more efficient but in some applications neither is ideal. An alternative technique is direct memory access (DMA). Once the data transfer has been initiated, the block of characters is output over the serial line without the intervention of the CPU which is then free for other tasks. This article describes the implementation of DMA on a Z80 system with serial I/O.
Few people apart from the original designers know how a digital IC actually works which, argues the author, often prevents users from finding new applications for a device. This paper presents a model of the Synertek 6502 peripheral interface adaptor which is designed to let users know details of operation and implementation that the designers know. Six levels and three sublevels of modelling are outlined and applied in detail to the 6502. This nonprocedural registertransfer structural-level model is intended to provide a unified approach to the understanding of 6502 hardware, interfacing and software. By having a model at this level of detail the new user or student needs less 'consultant level' assistance - he or she has more confidence in his or her own design.
Herman, M and Tweedy, l 'Enhance display-system designs with a processor/control IC' EDN Vol 26 No 21 (28 October 1981) pp 102-108 This article describes applications of the CRT 9007 video processor and controller (VPAC). This IC provides timing and microprocessor/displaytraffic-handling enhancements along with microprocessor-softwareunburdening, split-screen and bidirectional smooth scrolling, double height or width data display and flexible attribute handling.
Kinsel, T S and Wuorinen, J H 'A digital signal generator' IEEE Micro Vol 1 No 4 (November 1981) pp 6 - 1 5 The digital signal generator described in this article can provide low-distortion waveforms of precise frequency in the low-frequency audio spectrum and is implemented on a microcomputer. The strategy of using a microprocessor in the construction of such a generator allows one or more accumulators to be implemented by software to generate composite waveforms. This article includes the assembly listing for a program that generates a single continuous sine wave.
Hanson, D F 'An improved model for a microcomputer component - the 6520 PIA' IEEE Micro Vol 1 No 4 (November 1981 ) pp 1 7 - 2 5
82
Larson, L 'Test subtle ADC characteristics using only a scope and DVM' EDN Vol 26 No 21 (28 October 1981 ) pp 9 7 - 1 0 0
The operation of an A/D converter can be observed in real time by employing only an oscilloscope and a digital w)ltmeter (DVM). The test provides a visual indication o f the converter's basic operation and allows checks on noise and differential nonlinearity - a specification that quantifies deviations in the input voltage change required to produce a 1 -count outpu t-code change. The method described in this article avoids complicated test arrangements and simplifies the location of problems that might otherwise go uncorrected until late in the system-design process. Examples of the oscilloscope display and its interpretation are included in the article, Newman, M and Smith, D 'The MC6809 in DMA mode on the IEEE-488 bus' IEEE Micro Vol 1 No 4 /November 1981) pp 56 75 The MC6809 microprocessor is an 8-bit device that provides data transfer as well as computational capability. It also provides direct memory access control signals which allow maximum data transfer between memory and peripheral with minimum effect on processor operations. This article considers the use of the MC6809 in DMA mode to form a talker/listener IEEE-488 system. Alternative DMA approaches -- halt burst mode and cycle stealing Ithree-state steal) - are considered and the seven blocks of the DMA system employed are described in detail. The article concludes with an example test program showing how the MC68488 can be used with the 6809 in a DMA system.
Niewierski, W J 'Designing CMOS memory systems' Electron. Prod. Des. Vol 2 No 10 (October 1981) pp 57- 62 CMOS memory devices now stand beside their previously faster and cheaper NMOS counterparts. A wide range of CMOS RAMs are now available and include many approaches to nonvolatile memories such as battery back-up RAM and CMOS fuse-link PROMs. This article outlines many of the advantages of CMOS devices particularly the low power consumption which consists of two components, standby and operating power.
microprocessors and microsysterns
Hall, A 'A Z80 serial interface using DMA' Electron. Prod. Des. Vol 2 No 10 (October 1981 ) pp 4 3 - 4 6 The transfer of ASCII characters over a serial communications link is normally achieved either by having the serial interface interrupt the CPU when it needs another character or by having the CPU continuously poll the interface, waiting for it to indicate that it is ready to receive another character. The first of these two operations is more efficient but in some applications neither is ideal. An alternative technique is direct memory access (DMA). Once the data transfer has been initiated, the block of characters is output over the serial line without the intervention of the CPU which is then free for other tasks. This article describes the implementation of DMA on a Z80 system with serial I/O.
Few people apart from the original designers know how a digital IC actually works which, argues the author, often prevents users from finding new applications for a device. This paper presents a model of the Synertek 6502 peripheral interface adaptor which is designed to let users know details of operation and implementation that the designers know. Six levels and three sublevels of modelling are outlined and applied in detail to the 6502. This nonprocedural registertransfer structural-level model is intended to provide a unified approach to the understanding of 6502 hardware, interfacing and software. By having a model at this level of detail the new user or student needs less 'consultant level' assistance - he or she has more confidence in his or her own design.
Herman, M and Tweedy, l 'Enhance display-system designs with a processor/control IC' EDN Vol 26 No 21 (28 October 1981) pp 102-108 This article describes applications of the CRT 9007 video processor and controller (VPAC). This IC provides timing and microprocessor/displaytraffic-handling enhancements along with microprocessor-softwareunburdening, split-screen and bidirectional smooth scrolling, double height or width data display and flexible attribute handling.
Kinsel, T S and Wuorinen, J H 'A digital signal generator' IEEE Micro Vol 1 No 4 (November 1981) pp 6 - 1 5 The digital signal generator described in this article can provide low-distortion waveforms of precise frequency in the low-frequency audio spectrum and is implemented on a microcomputer. The strategy of using a microprocessor in the construction of such a generator allows one or more accumulators to be implemented by software to generate composite waveforms. This article includes the assembly listing for a program that generates a single continuous sine wave.
Hanson, D F 'An improved model for a microcomputer component - the 6520 PIA' IEEE Micro Vol 1 No 4 (November 1981 ) pp 1 7 - 2 5
82
Larson, L 'Test subtle ADC characteristics using only a scope and DVM' EDN Vol 26 No 21 (28 October 1981 ) pp 9 7 - 1 0 0
The operation of an A/D converter can be observed in real time by employing only an oscilloscope and a digital w)ltmeter (DVM). The test provides a visual indication o f the converter's basic operation and allows checks on noise and differential nonlinearity - a specification that quantifies deviations in the input voltage change required to produce a 1 -count outpu t-code change. The method described in this article avoids complicated test arrangements and simplifies the location of problems that might otherwise go uncorrected until late in the system-design process. Examples of the oscilloscope display and its interpretation are included in the article, Newman, M and Smith, D 'The MC6809 in DMA mode on the IEEE-488 bus' IEEE Micro Vol 1 No 4 /November 1981) pp 56 75 The MC6809 microprocessor is an 8-bit device that provides data transfer as well as computational capability. It also provides direct memory access control signals which allow maximum data transfer between memory and peripheral with minimum effect on processor operations. This article considers the use of the MC6809 in DMA mode to form a talker/listener IEEE-488 system. Alternative DMA approaches -- halt burst mode and cycle stealing Ithree-state steal) - are considered and the seven blocks of the DMA system employed are described in detail. The article concludes with an example test program showing how the MC68488 can be used with the 6809 in a DMA system.
Niewierski, W J 'Designing CMOS memory systems' Electron. Prod. Des. Vol 2 No 10 (October 1981) pp 57- 62 CMOS memory devices now stand beside their previously faster and cheaper NMOS counterparts. A wide range of CMOS RAMs are now available and include many approaches to nonvolatile memories such as battery back-up RAM and CMOS fuse-link PROMs. This article outlines many of the advantages of CMOS devices particularly the low power consumption which consists of two components, standby and operating power.
microprocessors and microsysterns