Comparison of uP/uC Chips As with all computer devices, the advertised speeds and performance figures must be carefully interpreted. These numbers tend to measure only the performance of the manufacturer's test cases and may not be directly omparable [see Hennessey and Patterson, 1990]. These numbers may not be applicable to any one users requirements. Since the market for uP/uC chips is highly competitive, small differences become amplified dvertising Unfortunately, getting a valid number for comparison purposes requires an extensive effort at benchmarking The advertised performance figures may be taken as a guide, if the task is similar to the benchmark programs. If the processor does not pass the comparison with a comfortable margin, however, one should opt for a higher performance version of the same chip(if much programming already has been done)or select a clearly superior other candidate Trends in uP/uC Developments An entire microprocessor may be used as a building block in an application-specific integrated circuit(ASIC), available from various vendors. ASIC and vlSI design tools may be used to design such systems, tailored to specific user applications. The uP manufacturers are developing uC chips extending the use of their basic processors. For any application, the best procedure is to invite several vendors to propose alternate systems Current chips are merely indications of devices to come High-performance uP systems are becoming more RISC (reduced instruction set computer)oriented. The object is to execute one instruction per clock period (versus the prevailing 3 to 7 cycles)and to obtain a more regular processor structure. The most popular uP/uC systems are CISC processors. For a user it makes little difference what the internal structure of the processor is; the availability of user support software is far more critical. The trend is to make processors simpler, thus speeding up program execution, even if some programs may have to use more program steps in replacing many"convenience"instructions Nevertheless, the very high end uP systems have such a wide data path(32 or 64 bits)that more than one instruction may be accessed at one time. These machines are termed very long instruction word (VLIw) machines. They are able to execute more than one instruction per clock cycle, but they will be more complex internally. For users, both the simpler RISC and the complex VLIW machines will provide increased performance Microelectronics is able to produce 2 million transistor chips. While they are expensive, they will replace virtually all of the peripheral chips: memory, timers, and communication channels can all be controlled from a single chip. However, the humble 8-bit chip is still be the most cost-effective workhorse of the bulk of uc Defining Terms Die: The piece a silicon wafer containing all electronics. Feature size: The characteristic size of electronic components on a die Microcontroller(HC): A microelectronic chip incorporating a uP and memory, communication, as well as other computer support functions. Microprocessor (uP): A microelectronic chip that carries out all operations of a computer central processing unit: instruction fetch, execution, interrupt and management of address, data and control lines which are connected to the chip Peripheral: Device that supports the functions of the processor. The peripheral may be all electronic (a communications adapter)or may contain mechanical parts(a disk memory). To the processor a periph eral appears as electronics with timing constraints Related Topic e 2000 by CRC Press LLC
© 2000 by CRC Press LLC Comparison of mP/mC Chips As with all computer devices, the advertised speeds and performance figures must be carefully interpreted. These numbers tend to measure only the performance of the manufacturer’s test cases and may not be directly comparable [see Hennessey and Patterson, 1990]. These numbers may not be applicable to any one user’s requirements. Since the market for mP/mC chips is highly competitive, small differences become amplified in advertising. Unfortunately, getting a valid number for comparison purposes requires an extensive effort at benchmarking. The advertised performance figures may be taken as a guide, if the task is similar to the benchmark programs. If the processor does not pass the comparison with a comfortable margin, however, one should opt for a higherperformance version of the same chip (if much programming already has been done) or select a clearly superior other candidate. Trends in mP/mC Developments An entire microprocessor may be used as a building block in an application-specific integrated circuit (ASIC), available from various vendors. ASIC and VLSI design tools may be used to design such systems, tailored to specific user applications. The mP manufacturers are developing mC chips extending the use of their basic processors. For any application, the best procedure is to invite several vendors to propose alternate systems. Current chips are merely indications of devices to come. High-performance mP systems are becoming more RISC (reduced instruction set computer) oriented. The object is to execute one instruction per clock period (versus the prevailing 3 to 7 cycles) and to obtain a more regular processor structure. The most popular mP/mC systems are CISC processors. For a user it makes little difference what the internal structure of the processor is; the availability of user support software is far more critical. The trend is to make processors simpler, thus speeding up program execution, even if some programs may have to use more program steps in replacing many “convenience” instructions. Nevertheless, the very high end mP systems have such a wide data path (32 or 64 bits) that more than one instruction may be accessed at one time. These machines are termed very long instruction word (VLIW) machines. They are able to execute more than one instruction per clock cycle, but they will be more complex internally. For users, both the simpler RISC and the complex VLIW machines will provide increased performance. Microelectronics is able to produce 2 million transistor chips. While they are expensive, they will replace virtually all of the peripheral chips: memory, timers, and communication channels can all be controlled from a single chip. However, the humble 8-bit chip is still be the most cost-effective workhorse of the bulk of mC applications. Defining Terms Die: The piece a silicon wafer containing all electronics. Feature size: The characteristic size of electronic components on a die. Microcontroller (mC): A microelectronic chip incorporating a mP and memory, communication, as well as other computer support functions. Microprocessor (mP): A microelectronic chip that carries out all operations of a computer central processing unit: instruction fetch, execution, interrupt and management of address, data and control lines which are connected to the chip. Peripheral: Device that supports the functions of the processor. The peripheral may be all electronic (a communications adapter) or may contain mechanical parts (a disk memory). To the processor a peripheral appears as electronics with timing constraints. Related Topic 82.2 Applications
References A Clements, Microprocessor System Design, Boston: PWS Publishers, 1987 R.S. Gaonkar, Microprocessor Architecture, Programming, and Applications with the 8085/8080A, 2nd ed, Colum bus, Ohio: Merrill Publishing Company, 1984 J.L. Hennessey and D.A. Patterson, Computer Architecture: A Quantitative Approach, Palo Alto, Calif: Morgan Kaufmann Publishers, 1990 M.C. Markowitz, EDN's 24th annual uP/uC chip directory, " EDN Magazine, September 25, 1997 J.R. Mick and J. Brick, Bit-Slice Microprocessor Design, New York: McGraw-Hill, 1980 G J. Myers and D L. Budde, The 80960 Microprocessor Architecture, New York: Wiley Interscience, 1988. J.B. Peatman, Design with Microcontrollers, New York: McGraw-Hill, 1988 M. Rafiquzzaman, Microprocessors and Microcomputer-Based System Design, Boca Raton, Fla. CRC Press, 1990 Further information The magazine EDN runs an annual microprocessor/microcontroller review, typically late in the year (i.e September 25, 1997). These are handy compendia of characteristics The IEEE magazine Micro presents detailed articles on device development and applications of micropro- cessors and systems which embed them. At mid-year the magazine carries a set of articles based on the Hot Chips Symposium, presenting developments in uP and chip technology for high-performance workstations and systems Specifics of various microprocessor and microsystem chips are found in the respective manufacturer's reference literature; for any design one must become familiar with the applicable manual and design notes Even for a modest chip the reference manual may run 300 pages; in addition, the manufacturer's free-of-charge ipport software is of comparable size. For example the Motorola 68HCll reference manual is 512 pages, and there is over 1 megabyte of design support software available from the manufacturer. The Intel i860 data book 150 pages, hardware and programmer reference manuals are over 300 pages, and the support software is several mega 82.2 Applications Phillip windley and James F. frenzel Microprocessors are cheap, small, and consume little power. In addition, in recent years their performance has increased at a greater rate than the performance of larger computers. These factors have led to an explosion the application of microprocessors. A short section could never do justice to every application; therefore, we will view representative applications in three broad areas: Data collection, where microprocessors are used to monitor sensors and either record the collected information or communicate the information to some other computer Control, where microprocessors have largely replaced analog electronics for controlling everything from anufacturing robots to home appliances. Computing, where microprocessors have transformed the concept of computer and made parallel pre Admittedly, these categories are not strictly disjoint. They do, however, represent the most pervasive uses for microprocessors at an abstract level. Data Collection In data collection the microprocessor-based system serves primarily as a low-cost data recorder. Basic functions include the polling of sensors, acceptance of data, data storage, and data transmission or display. Additional features might include preprocessing of the raw data. Such a classification spans a broad range of applications, from automotive diagnostics to space-born monitoring stations e 2000 by CRC Press LLC
© 2000 by CRC Press LLC References A. Clements, Microprocessor System Design, Boston: PWS Publishers, 1987. R.S. Gaonkar, Microprocessor Architecture, Programming, and Applications with the 8085/8080A, 2nd ed., Columbus, Ohio: Merrill Publishing Company, 1984. J.L. Hennessey and D.A. Patterson, Computer Architecture: A Quantitative Approach, Palo Alto, Calif.: Morgan Kaufmann Publishers, 1990. M.C. Markowitz, “EDN’s 24th annual mP/mC chip directory,” EDN Magazine, September 25, 1997. J.R. Mick and J. Brick, Bit-Slice Microprocessor Design, New York: McGraw-Hill, 1980. G.J. Myers and D.L. Budde, The 80960 Microprocessor Architecture, New York: Wiley Interscience, 1988. J.B. Peatman, Design with Microcontrollers, New York: McGraw-Hill, 1988. M. Rafiquzzaman, Microprocessors and Microcomputer-Based System Design, Boca Raton, Fla.: CRC Press, 1990. Further Information The magazine EDN runs an annual microprocessor/microcontroller review, typically late in the year (i.e., September 25, 1997). These are handy compendia of characteristics. The IEEE magazine Micro presents detailed articles on device development and applications of microprocessors and systems which embed them. At mid-year the magazine carries a set of articles based on the Hot Chips Symposium, presenting developments in mP and chip technology for high-performance workstations and systems. Specifics of various microprocessor and microsystem chips are found in the respective manufacturer’s reference literature; for any design one must become familiar with the applicable manual and design notes. Even for a modest chip the reference manual may run 300 pages; in addition, the manufacturer’s free-of-charge support software is of comparable size. For example the Motorola 68HC11 reference manual is 512 pages, and there is over 1 megabyte of design support software available from the manufacturer. The Intel i860 data book is 150 pages, hardware and programmer reference manuals are over 300 pages, and the support software is several megabytes. 82.2 Applications Phillip J. Windley and James F. Frenzel Microprocessors are cheap, small, and consume little power. In addition, in recent years their performance has increased at a greater rate than the performance of larger computers. These factors have led to an explosion in the application of microprocessors. A short section could never do justice to every application; therefore, we will view representative applications in three broad areas: • Data collection, where microprocessors are used to monitor sensors and either record the collected information or communicate the information to some other computer. • Control, where microprocessors have largely replaced analog electronics for controlling everything from manufacturing robots to home appliances. • Computing, where microprocessors have transformed the concept of computer and made parallel processing possible. Admittedly, these categories are not strictly disjoint. They do, however, represent the most pervasive uses for microprocessors at an abstract level. Data Collection In data collection the microprocessor-based system serves primarily as a low-cost data recorder. Basic functions include the polling of sensors, acceptance of data, data storage, and data transmission or display. Additional features might include preprocessing of the raw data. Such a classification spans a broad range of applications, from automotive diagnostics to space-born monitoring stations