Simulation attributes of computer hardware description languages

Bassett, S 'Microprocessors: speed up, price down, and CMOS everywhere' Comput. Des. Vol 22 No 11 (October 1983) pp 177-187 Slager, J 'Advanced features squeeze onto processor chip' Comput. Des. Vol 22 No 11 (October 1983) pp 189-193 Gavrielov, M, Kaminker, A and Sidi, Y-T 'Coprocessors speed floating point calculations' Comput. Des. Vol 22 No 11 (October 1983) pp 197-204 Alpert, D 'Powerful 32-bit micro includes memory management' Comput. Des. Vol 22 No 11 (October 1983) pp 213-220 Folkes, D and Bates, J 'Microcontroller addresses control and instrumentation' Comput. Des. Vol 22 No 11 (October 1983) pp 229-237 Matney, R 191,Orban, A and Albers, TM 'Microprogramming for the masses' Comput. Des. Vol 22 No 11 (October 1983) pp 241-246 Evolution, not revolution, is how Bassett describes the current developments in microprocessors. He examines the main trends towards shrinking geometries and increased processing speeds. Some typical controllers are considered, both 8-bit and 16-bit types. These include the Motorola 6800 family, and devices from Zilog and Texas Instruments. Bassett takes a look at the designer's perspective. The orthogonal architecture of the National Semiconductor 16000 family gets a particular mention. On the horizon the author sees 32-bit chip sets becoming more and more popular. Speculation about which will be the most active firms in the microprocessor industry ends the article. Slager concentrates on 16-bit microprocessors, and in particular the Intel iAPX 286. Some of the considerations that occupy designers are discussed, eg how shrinking memory access times must be traded off for increases in chip performance produced by increasing the microprocessor's clock frequency. Memory management and protection are included on the iAPX 286 chip to keep delays as short as possible, even though this means greater complexity of design. Partition-

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ing for throughput and improving the bus bandwidth are also discussed. Slager asserts that the iAPX 286 does not just meet the functional needs of its users, it also protects users from one another and protects the system software from its users. The third article in this special report gives the philosophy behind the National Semiconductor 16081 floating point unit. This dedicated arithmetic processor does floating point computations for the NS16032 32-bit microprocessor. It is linked to the 16032 in a master-slave relationship. The architecture of the 16081 consists of three blocks: control, execution and I/O handling. Gavrielov et al. give an account of how arithmetic values are computed. Also included in the article is a summary of the IEEE P754 floating point standard. Semiconductor technology (or the lack of it) has prevented 16-bit microprocessors from giving central processing and memory management in the same integrated circuit, according to Alpert. The 32-bit Zilog Z80000 will change that, he claims. The system architecture is described. The organization of memory management is presented in detail. Some of the features of the Z80000 memory management scheme are implemented on the Z8003 virtual memory processing unit and Z8015 paged memory management unit. Alpert points out how 32-bit devices overcome some of the limitations of these two units. The 16-bit microcontroller described by Folkes and Bates has a 68000-1ike architecture. The 68200 has 48 pins available. The pinout configuration and the programming architecture are explained. A summary shows the resemblances between the instruction sets of the 68200 and the 68000. The two sets have several mnemonics in common. A linear scaling programming example illustrates the use of the 68200 set. Instruction coding may be on the brink of a revolution, suggest Matney et aL With microprogrammable singlechip processors and their associated software as weapons, designers can replace the traditional hardwired logic with microcode. This makes it much easier to change instruction sets in CPUs. New instructions can be added

to the standard set. Microcoding saves time, say the authors. To carry out an operation in assembly language, an output must be sent to a port, then the inverted bit is sent to the port, and a certain amount of looping occurs. In microcode a single instruction can b2 custom tailored to do the same job. That is all the instruction will do, bu[ it does it much faster. Matney do not ignore the problems associated with microcoding. However, various development tools have been produced to try and solve these problems. The authors predict growing use of mic¢ocoding, for simulators and automatic test pattern generators in particular. Osborne, J E 'Validating analyzer data: an approach to on-line process performance evaluation' Instrum. Technol. Vol 30 No 10 (October 1983) pp 49 .- 51 Microprocessors are integral parts of many systems for onstream composition analysis (eg gas chromatography). The operation of such a system can be saved from having to perform manual functions. At the same time diagnostics and selfcalibration built into the system can help to avoid failure and the use of bad data. The configuration of a setup for comprehensive verification of analytical data is given. The hardware comprises several computers and intelligent terminals arranged in a local area network. The software functions are summarized. An overview of the uses of the verification system is included. Osborne gives a brief account of the application of the data validation concept to a series of pilot vapour phase reactors. Shiva, S G and Patel, D C 'Simulation attributes of computer hardware description languages' Radio Electron. Eng. Vol 54 No I (January 1984) pp 45-50 Guidelines for comparing computer hardware description languages are given. These languages evolved as a means of inputting the design of digital systems for simulation and verification. The guidelines concentrate on the simulation properties of the languages. Various criteria for comparison are given, eg operators available, data abstraction capability, sequence control modelling and behaviour

microprocessors and microsystems