7/29/2019 Microassembler - Wikipedia, The Free Encyclopedia

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Microassemblerm Wikipedia, the free encyclopedia

microassembler is a computer program that helps prepare a microprogram to control the low level operation of a

mputer in much the same way an assembler helps prepare higher level code for a processor. The difference is that the

croprogram is usually only developed by the processor manufacturer and works intimately with the computer hardware.

e microprogram implements the operations of the instruction set in which any normal program (including both application

grams and operating systems) is written. The use of a microprogram allows the manufacturer to fix certain mistakes,

uding working around hardware design errors, without modifying the hardware. Another means of employingcroassembler-generated microprograms is in allowing the same hardware to run different instruction sets. After it is

embled, the microprogram is then loaded to a control store to become part of the logic of a CPU's control unit.

me microassemblers are more generalized and are not targeted at a single computer architecture. For example, through

use of macro-assembler-like capabilities, Digital Equipment Corporation used theirMICRO2 microassembler for a very

de range of computer architectures and implementations.

given computer implementation supports a writeable control store, the microassembler is usually provided to customers

a means of writing customized microcode.

he process of microcode assembly it is helpful to verify the microprogram with emulating tools before distribution.

wadays, microcoding has experienced a revival, since it is possible to correct and optimize the firmware (i.e. the

crocode) of processing units sold, in order for adaptation to operating systems or for bug fixing means. However, a

mmonly usable microassembler for today's CPUs is not available to manipulate the microcode. Unfortunately, it is difficult

obtain open knowledge about changing the microcode because of intellectual property reasons.

w microcode can be assembled with a microassembler to control a CPU with own created machine codes on

croprogramming basis, can be understood and simulated with e-learning tools like MikrocodesimulatorMikroSim on a

actial point of view.

xternal links

"Mikrocodesimulator MikroSim 2010" (http://www.mikrocodesimulator.de/index_eng.php). 0/1-SimWare.

Retrieved 2010-10-03.

"P6 Family Processor Microcode Update, Feature Review"

(http://www.sten.se/share/unix/kernel/microcode/microcode.pdf). J. Molina, W. Arbaugh. 2000. Retrieved 2010-

10-03.

"A Brief History ofMicroprogramming" (http://www.cs.clemson.edu/~mark/uprog.html). M. Smotherman. 2010.

Retrieved 2010-10-03.

"Computer Structures: Principles and Examples, Part 2, REGIONS OF COMPUTER SPACE, Section 1,

MICROPROGRAM-BASED PROCESSORS, Seite 151 ff." (http://research.microsoft.com/en-

us/um/people/gbell/Computer_Structures_Principles_and_Examples/csp0167.htm). McGraw-Hill Computer Science

Series. Retrieved 2010-10-03.

"Intel(R) 64 and IA-32 Architectures Software Developers Manual, Volume 3A: System Programming Guide, Part

1, Chapter 8.11: "Microcode update facilities"" (http://www.intel.com/Assets/PDF/manual/253668.pdf). Intel

Cooperation. December 2009. Retrieved 2010-10-03.

rieved from "http://en.wikipedia.org/w/index.php?title=Microassembler&oldid=540193461"

egories: Assemblers

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