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IEEE Computer Volume 15 Number 7 -- THE OPEN CHANNEL Disclosure Number: IPCOM000131518D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Nov-11
Document File: 10 page(s) / 35K

Publishing Venue

Software Patent Institute

Related People

Charles McCabe: AUTHOR [+3]



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This record contains textual material that is copyright ©; 1982 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Contact the IEEE Computer Society (714-821-8380) for copies of the complete work that was the source of this textual material and for all use beyond that as a record from the SPI Database.


Charles McCabe

The San Francisco Chronicle

"Any clod can have the facts but having opinions Is an art."

The Open Channel Is exactly what the name implies: a forum for the free exchange of technical ideas. Try to hold your contributions to one page maximum In the Final magazine format (about 1000 words).

We'll accept anything (short of libel or obscenity) so long as tYs submitted by a member of the Computer Society. If lYs really bizarre we may require you to get another member to cosponsor your Item.

Send everything to Jim Hayn - , Applied Sclences, UC Santa Cruz, Santa Cruz, CA 95064.

Trial implementation reveals errors in IEEE standard

The microprocessor assembly language standards is a concept that is welcomed by the users of microprocessors. Engineers who work with several different microprocessors, and students faced with the problem of learning several processors and their different assemblers in the same semester will be most appreciative. It is not unusual to have several assemblers using different directives and even different mnemonics available for the same microprocessor. We have two Z80 assemblers; one uses Zilog mnemonics and the other uses a mixture of Zilog Z80 and Intel 8080 mnemonics. What a welcome simplification it will be when the instruction to transfer the program execution to address NEXT if the negative flag is set is BN/NEXT and not JP M,NEXT for one assembler, or JM NEXT for another, or BMI NEXT for another, or . . .

Errors in the proposed mnemonics.

In the process of writing a 6800/8085 assembler following the IEEE P694 proposed microprocessor assembly language standard, we discovered several errors in the standard mnemonics. First, refer to Appendix B of the proposed standard for the list of the 6800 mnemonics.

(1) The enable interrupt and disable interrupt instructions are reversed. The 6800 instruction SKI sets the interrupt

mask and therefore disables the interrupt. The correct table entries are shown in Figure 1.

(2) The rotate right and rotate left instructions are misnamed. The 6800 does not have an 8-bit rotate, only a 9- bit rotate. The correct table entries are shown in Figure 2.

IEEE Computer Society, Jul 01, 1982 Page 1 IEEE Computer Volume 15 Number 7, Pages 76-80

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IEEE Computer Volume 15 Number 7 -- THE OPEN CHANNEL

(3) The 6800 instruction TST is not a logical instruction but an arithmetic instruction. The TST instruchon subtracts O from the data and is therefore a compare or CMP instruction. TST should be removed from the last line of the l...