Scsi termination, Kingston frame configuration – Teac MMR-16 v4.0 User Manual

Page 33

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MMP-16

TASCAM MMP-16 Owner’s Manual • Chapter 2 • Installation

35

Cabling Wide and Narrow Devices in a System

NARROW SCSI uses 8-bit data transfers. It generally uses a 50-pin connector.

WIDE SCSI uses 16-bit data transfers. It generally uses a 68-pin connector. Wide SCSI may also refer to
32-bit SCSI data transfers but 32-bit wide SCSI is not as common.

Narrow drives should always be placed at the end of a SCSI chain. This is due to the fact that when a
Wide to Narrow connection is made, 8 bits are not passed through, so the Wide drive (and all subsequent
SCSI devices in the chain) receives only 8 bits of data instead of 16. If a Narrow drive is connected after a
Wide drive, the Wide drive still receives all 16 bits of data.

SCSI Termination

A terminator provides electrical circuitry at the end of a SCSI chain to prevent the reflection of electrical
signals when they reach the end of the chain. The SCSI bus requires termination only at the ends of the
SCSI chain, not in the middle. There are several types of SCSI Termination: Passive, Active, Active
Negation, Force Perfect Termination, and Low Voltage Differential.

The MMR/MMP should only use Active terminators. This is because active terminators involve a
voltage regulator to reduce fluctuation effects in termination power to insignificance. This results in more
stable SCSI signals, less signal reflection and fewer data errors. Active negation terminators are most
optimized for Fast- and Ultra-SCSI speeds. Active negation termination is currently not under testing and
thus is not supported by TASCAM.

Kingston Frame Configuration

When configuring a Kingston receiving frame the settings in Figure 1 must be used.
Note: All but one setting are factory defaults. Jumpers should be installed on W3, W1 and pins 1&2 of J6
(Figure 1). Jumper W2 determines termination. In the “A” position (default) termination resistors are
disabled (This is the recommended configuration for most external applications). In certain conditions it
may be desirable to terminate at the frame, for example, if an internal bay is being installed in the
MMR/MMP. If this is the case jumper W2 should be set in the “B” position

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