Ultra320 SCSI

Ultra320 SCSI – Terms & Terminology


Data transfers 320 megabytes per second, first defined in SPI-4 – Fast-160

SCSI SPI-4 (SCSI Parallel Interface)

16 bit SCSI packetized commands with Synchronous data transfer rates up to 320 megabytes per second. LVD (Low Voltage Differential) SCSI is required SCSI SPI-4 for Fast-160DT. A new data transfer mode is required, with an 80 MHz free running clock to eliminate ISI problems with the clock signal, P1 gating signal is clocked with the free running clock for a valid transfer.


  1. Paced data transfer – Packetized SCSI
  2. Free running clock (ACK, REQ and P1 for valid data)
  3. ISI (Intersymbol Interference) Compensation – Precomp drivers and Adaptive Active Filter receivers
  4. SKEW Compensation
  5. Training pattern – for the adaptive active filters and the skew compensation
  6. Expander communications