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Learn gallium-arsenide basics before applying high-speed ICs
Part of a table compiled by US firm Multi Solutions is given. The table compares features such as portability, modularity, allocation and networking for CP/M, Concurrent CP/M, MP/M II, MS-DOS, Oasis, Pick, p-System, $1, Unix and Xenix. Efforts are being made to standardize on 16-bit operating systems, CP/M being the de facto 8bit standard. The work of the IEEE microprocessor operating system interface (MOSI) taks force 855 is outlined. Hinden concludes that there is still a lot to be done before a floppy disc can be put into any microcomputer to run a job.
Hoyle, B S 'Engineering microprocessor software' Electron. Power Vol 30 No 5 (May 1984) pp 395-399 The advent of microprocessors means that designers have a decision to make each time they initiate an electronics-based product or system project: should the central design be in software for a generalpurpose programmable device, or in purpose-designed hardware? Hoyle considers the advantages and disadvantages of the software solution. Not least of these is the current scarcity of software engineers. However, various tools exist to tackle the problems. Hoyle looks at some of these, and lists some features that the software's future environment should have. He also gives a few guidelines for creating purpose-built microcomputer hardware, should the user prefer this approach.
Karstad, K 'Instructions add flexibility to bitslice design ' Comput. Des. Vol 23 No 8 (July 1984) pp 105-112 Unlike single-chip microprocessors, microprogrammable bit-slice devices can be configured to allow various word lengths and instrucion sets. Karstad describes a controller for bit-slice central processing units. The emulating microcontroller (EMC) chip GP501 can interface to the GP001, and 8-bit register and arith-
vol 8 no 7 september 1984
metic logic unit in the same emulation programmable family of ICs. The EMC is made by the CMOS silicon-on-sapphire technique, but can be used with bit slices made by other methods as well. Karstad demonstrates the internal logic structure of the EMC. He discusses the design goals of the EMC and how these are met. The eight operation codes in the 1 g-bit control word are summarized in a table. Command assignment is explained and the implications of designing real systems to include the EMC are considered.
MacMillan, D and Gheewala, T 'Learn gallium-arsenide basics before applying high-speed Its' EDN Vo129 No 6 (22 March 1984) pp 239-246 Many systems that were impossible or impractical to build with silicon semiconductors can be constructed using GaAs ICs. GaAs technology combines high operating speeds with low power consumption, say MacMillan and Gheewala. They present the basics of GaAs logic devices and of the ICs based on them in a threepart series, of which this is the first part. Here devices such as Schottky diodes, depletion- and enhancement-mode MESFETs and highelectron-mobility transistors are examined. GaAs circuit techniques such as buffered FET logic and Schottky-diode FET logic are compared. The authors recommend that early GaAs IC production be restricted to small- (SSI) and medium-scale integration (MSI) to keep costs down while gaining experience in prod u ction-lin e technology. A GaAs fibre-optic repeater system is presented as an example of how even SSI and MSI devices can be useful. More complex devices, eg 1 kbit RAMs and 200- or 400-gate GaAs gate arrays, are still in the development stage. However, even they may be in production in a few months, say the authors.
Magill, J and Thomsen, G 'Complex datacomm peripheral ICs interface to many processors'
EDN Vol 29 No 6 (22 March 1984)
pp 177-184 Distributed processing trends mean that computation can be carried out closer and closer to where information is gathered or displayed. Magill and Thomsen give a guide to communication protocols and how they can be implemented with currently available datacommunication peripherals. They concentrate on device-to-device links rather than bus architecture interconnects. The peripheral devices featured are based on the 68000 family of processors. Four are looked at individually: a 68652 multiprotocol communications controller, a 68653 polynomial generator checker, a 68681 enhanced programmable communication interface and a 68681 dual universal asynchronous receiver/transmitter. Design examples are given to help readers select the proper device for their own systems. The cases for and against using 8-bit instead of 16-bit devices are argued. Asynchronous devices are recommended over synchronous because, although the circuit design must be a bit more complex, asynchronous setups can minimize software requirements. Bisync mode operation is favoured even more.
Mokhoff, N 'Thirty-two bit micros power workstations' Comput. Des. Vo123 No 7 (15 June 1984) pp 97-112 Proprietary 32-bit bus schemes such as Multibus II, VMEbus and Futurebus, are usually related to a particular hardware configuration. Their appeal to the whole design community is therefore limited. Compatibility with existing 8-bit and 16-bit installations is also an important consideration. Mokhoff reviews the National Semiconductor 32032 and some of the systems that have incorporated it. He also looks at a workstation that will be based on the Motorola 68020's 32bit architecture. The views of some industry managers on Unix and its Iookalikes are included.
387
Hoyle, B S 'Engineering microprocessor software' Electron. Power Vol 30 No 5 (May 1984) pp 395-399 The advent of microprocessors means that designers have a decision to make each time they initiate an electronics-based product or system project: should the central design be in software for a generalpurpose programmable device, or in purpose-designed hardware? Hoyle considers the advantages and disadvantages of the software solution. Not least of these is the current scarcity of software engineers. However, various tools exist to tackle the problems. Hoyle looks at some of these, and lists some features that the software's future environment should have. He also gives a few guidelines for creating purpose-built microcomputer hardware, should the user prefer this approach.
Karstad, K 'Instructions add flexibility to bitslice design ' Comput. Des. Vol 23 No 8 (July 1984) pp 105-112 Unlike single-chip microprocessors, microprogrammable bit-slice devices can be configured to allow various word lengths and instrucion sets. Karstad describes a controller for bit-slice central processing units. The emulating microcontroller (EMC) chip GP501 can interface to the GP001, and 8-bit register and arith-
vol 8 no 7 september 1984
metic logic unit in the same emulation programmable family of ICs. The EMC is made by the CMOS silicon-on-sapphire technique, but can be used with bit slices made by other methods as well. Karstad demonstrates the internal logic structure of the EMC. He discusses the design goals of the EMC and how these are met. The eight operation codes in the 1 g-bit control word are summarized in a table. Command assignment is explained and the implications of designing real systems to include the EMC are considered.
MacMillan, D and Gheewala, T 'Learn gallium-arsenide basics before applying high-speed Its' EDN Vo129 No 6 (22 March 1984) pp 239-246 Many systems that were impossible or impractical to build with silicon semiconductors can be constructed using GaAs ICs. GaAs technology combines high operating speeds with low power consumption, say MacMillan and Gheewala. They present the basics of GaAs logic devices and of the ICs based on them in a threepart series, of which this is the first part. Here devices such as Schottky diodes, depletion- and enhancement-mode MESFETs and highelectron-mobility transistors are examined. GaAs circuit techniques such as buffered FET logic and Schottky-diode FET logic are compared. The authors recommend that early GaAs IC production be restricted to small- (SSI) and medium-scale integration (MSI) to keep costs down while gaining experience in prod u ction-lin e technology. A GaAs fibre-optic repeater system is presented as an example of how even SSI and MSI devices can be useful. More complex devices, eg 1 kbit RAMs and 200- or 400-gate GaAs gate arrays, are still in the development stage. However, even they may be in production in a few months, say the authors.
Magill, J and Thomsen, G 'Complex datacomm peripheral ICs interface to many processors'
EDN Vol 29 No 6 (22 March 1984)
pp 177-184 Distributed processing trends mean that computation can be carried out closer and closer to where information is gathered or displayed. Magill and Thomsen give a guide to communication protocols and how they can be implemented with currently available datacommunication peripherals. They concentrate on device-to-device links rather than bus architecture interconnects. The peripheral devices featured are based on the 68000 family of processors. Four are looked at individually: a 68652 multiprotocol communications controller, a 68653 polynomial generator checker, a 68681 enhanced programmable communication interface and a 68681 dual universal asynchronous receiver/transmitter. Design examples are given to help readers select the proper device for their own systems. The cases for and against using 8-bit instead of 16-bit devices are argued. Asynchronous devices are recommended over synchronous because, although the circuit design must be a bit more complex, asynchronous setups can minimize software requirements. Bisync mode operation is favoured even more.
Mokhoff, N 'Thirty-two bit micros power workstations' Comput. Des. Vo123 No 7 (15 June 1984) pp 97-112 Proprietary 32-bit bus schemes such as Multibus II, VMEbus and Futurebus, are usually related to a particular hardware configuration. Their appeal to the whole design community is therefore limited. Compatibility with existing 8-bit and 16-bit installations is also an important consideration. Mokhoff reviews the National Semiconductor 32032 and some of the systems that have incorporated it. He also looks at a workstation that will be based on the Motorola 68020's 32bit architecture. The views of some industry managers on Unix and its Iookalikes are included.
387