Digital Electronics: Principles, Devices and Applications

Computer Fundamentals 64115.8.2.1 IEEE-488IEEE-488 is a short-range parallel bus standard widely used in test and measurement applications.It is also referred to as a general-purpose interface bus (GPIB). The IEEE 488 standard specifies a24-wire connection for transferring eight data bits simultaneously. Other connections include eightcontrol signals and eight ground lines. The maximum data rate is 1 MB/s in the original standard andabout 8 MB/s with the modified standard (HS-488). Figure 15.31 shows the pin connections and pindetails.15.8.2.2 Small Computer System Interface (SCSI)SCSI is a widely used standard for interfacing personal computers and peripherals. SCSI is astandard given by the American National Standards Institute (ANSI). There are several variationsof this standard, and one variant may not be compatible with another. Some of the SCSI versionsinclude SCSI-1, SCSI-2, Wide SCSI, Fast SCSI, Fast Wide SCSI, Ultra SCSI, SCSI-3, UltraSCSI-2 and Wide Ultra SCSI-2. Description of all these interfaces is beyond the scope of thisbook.15.8.2.3 IEEE-1284IEEE 1284 is a standard that defines bidirectional parallel communications between computers andother devices. It supports a maximum data rate of 4 MB/s. It supports three types of connector: DB-25(type A) for the host connection, Centronics 36-pin (type B) for the printer or device connectionand Mini Centronics 36-pin (type C), a smaller alternative for the device connection. IEEE 1284-I1 1213 241EEE 488 ConnectorPinouts1. Data 1/O12. Data 1/O23. Data 1/O34. Data 1/O45. EOI (End or Identity)6. DAV (Data Valid)7. NRFD (Not Ready for Data)8. NDAC (Not Data Accepted)9. IFC (Interface Clear)10. SRQ (Service Request)11. ATN (Attention)12. Sheild Ground13. Data 1/O514. Data 1/O615. Data 1/O716. Data 1/O817. REN ( Remote Enable)18. P/O Twisted Pair with 619. P/O Twisted Pair with 720. P/O Twisted Pair with 821. P/O Twisted Pair with 922. P/O Twisted Pair with 1023. P/O Twisted Pair with 1124. Signal GroundFigure 15.31Pin connections and details of the IEEE-488 connector.