Unaligned Double Word Fetch
Original Publication Date: 1988-Apr-01
Included in the Prior Art Database: 2005-Feb-15
This invention differs from other methods of handling unaligned double words of data in that the processor does not have to know whether or not the data is not aligned. All alignment checking is done by a Storage Control Unit, and a second fetch is done only if necessary. The processor also does not have to handle the data differently in the case of aligned verses unaligned data. A Storage Control Unit (SCU) receives a request from the processor to do a fetch and is told that the data may be unaligned. The SCU checks the address and if it is not double word aligned it will automatically kick off a second access. The SCU also has two lines to the processor telling it which full word to latch from the memory data bus.