Control method and apparatus for controlling the data flow rate in a FIFO memory, for synchronous SCSI data transfers
US5237660A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 27, 1988 |
| Grant date | Aug 17, 1993 |
| Priority date | — |
| Expiry date | Dec 27, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F13/423
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A circuit for use with a SCSI interface for controlling synchronous data transfers into an attached FIFO memory. The circuit uses a comparator to keep track of the number of FIFO locations available by starting with a threshold value, which represents the locations available initially, and comparing the net number of FIFO locations filled to the threshold value. The net number of FIFO locations filled is kept by a counter which counts the difference between the words transferred into the FIFO and the words transferred out of the FIFO. The threshold value is an adjusted offset value if the SCSI interface is operating in INITIATOR mode, and the FIFO size if the SCSI interface is operating in TARGET mode. When the comparator determines that the FIFO is filled, it pauses the current synchronous message by withholding an ACK in the INITIATOR mode or a REQ in the TARGET mode.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.