System for obtaining correct byte addresses by XOR-ING 2 LSB bits of byte address with binary 3 to facilitate compatibility between computer architecture having different memory orders
US5398328A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 27, 1983 |
| Grant date | Mar 14, 1995 |
| Priority date | — |
| Expiry date | Sep 27, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/34
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for enabling a computer to run using either a Big Endian or Little Endian architecture is provided. The method and apparatus use the fact that XORing the lower two bits of a byte address in one architecture with a binary 3 converts that byte address to the equivalent byte address in the other architecture. The conversion method and apparatus is implemented in hardware by setting a bit in a status register indicating a Big Endian or Little Endian architecture in conjunction with an XOR gate which couples the byte address to binary 3. The conversion method and apparatus is implemented in software by scanning the instructions of the input for load and store instructions. The software modifies the instructions by taking the contents of the register and XORing the two least significant bits of the byte address with a binary 3.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.