A guide to flexible disk drive selection

Hardware Capece, R P 'Older processes revamped as new arrivals extend performance limits' Electronics Vol 52 No 19 (13 September 1979) pp 109-123 This is the first article in a special report on developments in LSI processes. The new MOS processes are described and their various merits discussed. VMOS technology produces the greatest cell density and would appear to be the choice for the new generation 64k static rams; CMOS has the advantage of extremely low power consumption in standby mode, making it useful for large, fast memory systems, and .HMOS processes have produced RAMs with access times as fast as 35 ns. The state of bipolar and gallium arsenide technology is also included, and a table comparing process properties is given. Cushmann, R H 'Special-architecture one-chip microcomputers aim for versatility and power' EDN Vol 24 No 12 (20 J une 1979) pp ] 19-127 Part of a series, this article surveys special-architecture devices that comprise the middle range of one-chip microcomputers e.g. Intel 8048, Zilog Z8 and General Instruments PIC, focusing on the latter's particularly unusual features. Although sharing the common split architecture of the others, the PIC family has a ROM width of 12 bits, which enables all its instructions to be kept to one line of ROM and one cycle of execution. Erdman, R L 'A guide to flexible disk drive selection' Digital Des. Vol 9 No 7 (July 1979) pp 4 6 - 5 0 Criteria to be considered when choosing a disc drive are discussed. Compatibility of data format, capacity, and methods of data protection are covered and a checklist of features is given.

Farly, B 'When logic analysers meet development systems' Electronics Vol 52 No 19 (13 September 1979) pp 141-146 The overlapping of microprocessor development system and logic analyser

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applications is a source of confusion for the hardware designer. This article attempts to determine the role of the logic analyser and discusses its advantages in a variety of applications. George, P K and Reyling, G 'Bubble memories come to the boil' Electronics Vol 52 No 16 (2 August 1979) pp 9 9 - 1 0 8 Principles of bubble memory operation are described and technology and design requirements discussed. New current-access technology could solve po~er supply and performance problems associated with field-access technology by bringing bubble memories into the 5 V supply regime and eliminating drive coils. Also the propogating pattern for the next generation of 4 Mbit devices may change from the conventional asymmetric-chevron array to the greater yielding contiguous-disc pattern.

Gooz~, M 'How a 16-bit microprocessor makes it in an 8-bit world' Electronics Vol 52 No 20 (27 September 1979) p 122-.125 A description of the Motorola 6809 microprocessor. This 16-bit device can interface with an 8-bit bus, and is compatible with 6800 hardware. Details of the instruction set and addressing modes are given, with a discussion of its application to modular programming. Gundling, W E and Schade, P A 'Programmable devices: their advantages and disadvantages and programming equipment - Part ] 'Digital Des. Vol 9 No 9 (September ] 979) pp 2 6 - 3 4 In this first half of a two-part article, the range of programmable devices available is explored. There are general discussions of PROMs, EPROMs, EAROMs etc. and a table shows how each device rates in terms of ease of programming and use, access times, reliability and second sourcing. Nissen, J C D and Geiger, G V 'A fault-tolerant multimicroprocessor for telecommunications and general applications' GEC Jour. of Sci. and Tech. Vol 45 N o 3 (1979) pp 116-122 A multimicroprocessor for control of a telephone exchange system is

described. The system consists o/ processing modules that may be connected for distributed or centralized control or a combination of both; it is programmed in CORAL 66. Details of system requirements are given, and of reliability features.

Software Alien, J 'An overview of LISP' Byte Vol 4 No 8 (August 1979) pp 10-122 LISP (LISt Processing language) is described here as a 'high level machine language'. That is to say a LISP machine has data items organized differently from the binary bitpatterns of most machines, and the LISP programming language is the assembly language for the machine. Details of data structure and syntax are given as well as some discussion of LISP's potential. Bishop, J M 'Implementing strings in PASCAL ~ Software Pract. Exper. Vol 9 No 9 (September 1979) pp 779 788. Although file manipulation programs as a method of implementing strings are possible on current PASCAL systems, they are generally slow and subject to considerable restrictions. Realization of strings as linked chunks using existing sequence abstraction is described. Implementation is done in such a way as to leave existing programs undisturbed should strings be subsequently incorporated in the language and/or compiler. Bowden, K and Leather, C 'The Apple 11 as an intelligent interactive graphics terminal'Micro. App/. Vol 3 No 3 (September 1979) pp 28--42 The article presents results of research activities ata polytechnic computing centre. The aim was to make the Apple appear as an intelligent, interactive graphics terminal to an ICL 1904S multiaccess system. Practical details of using the Apple communications interface to link it with the mainframe are given. General graph plotter emulators and a Calcomp emulator for the Apple are described, including the use of a high resolution

microprocessors and microsystems