RZ6 Overview
The RZ6 Multi I/O Processor is a high sample rate processor with flexible input/
output capabilities. The RZ6 features up to four digital signal processors cards; any
card can be either a single standard processor card (RZDSP) or a quad-core
processor card (QZDSP). Standard single processor cards use a single Sharc DSP,
quad-core processor cards use four Sharc DSPs cores with the potential to more
than double the power of the RZ6. All cards are networked in an optimized
multiprocessor architecture that features efficient onboard communication and memory
access. Two channels each of sigma-delta D/A and A/D converters provide a
dynamic range of up to 115 dB and sampling rates up to ~200 kHz.
The single device form factor incorporates two channels of onboard programmable and
manual attenuation and can drive headphones and standard, magnetic, or electrostatic
speakers. It includes an onboard monitor speaker, two channels of amplification for
analog inputs, and 24 channels of digital I/O. XLR, audio jack, and BNC
connections are supported. Optionally, the RZ6 can be equipped with a fiber optic
input, allowing it to support a four channel Medusa preamplifier.
The RZ6-A base version starts with a single DSP and makes an excellent all-inone psychoacoustics system or can be added to any system to add audio stimulus
generation to experiments.
The RZ6-A-P1 comes equipped with three DSPs for more processing power and
includes the optional fiber optic input port, allowing it to serve as a BioAmp base
station for ABR and OAE studies.
Both configurations can be upgraded with additional single or quad-core DSP cards
(up to a maximum of four DSP cards) for complex filtering and high frequency
RZ6 Multi I/O Processor
System 3
Power and Communication
The RZ6's Optibit optical interface ensures fast and reliable data transfer from the
RZ6 to the PC and is integrated into the device. Connectors are provided on the
back panel and are color coded for correct wiring. The RZ6’s power supply is also
integrated into the device and is shipped from the factory configured for the desired
voltage setting (110 V or 220 V). If you need to change the voltage setting,
please contact TDT support at 386.462.9622 or email support@tdt.com.
The RZ6 is UL compliant, see the RZ5/RZ5D/RZ6 Operations Manual for power
and safety information.
Software Control
TDT Synapse or BioSigRZ software controls the RZ6 and provides users a high level
interface for device configuration. Device programming is implemented with circuit files
developed using TDT's RP Visual Design Studio (RPvdsEx). Circuits are loaded to
the processor through TDT run-time applications or custom applications. Several RZ6
macros are provided and are required to handle all programmable features related to
the RZ6. This manual includes device specific information needed during circuit
design. For circuit design techniques and a complete reference of the RPvdsEx circuit
components, see the RPvdsEx Manual.
RZ6 Multi‐Bus Architecture
The RZ6 processor utilizes a multi-bus architecture and offers four dedicated, data
buses for fast, efficient data handling. While the operation of the system architecture
is largely transparent to the user, a general understanding is important when
developing circuits in RPvdsEx.
RZ6 Multi I/O Processor
System 3
As shown in the diagram above, the RZ6 architecture consists of three
functional blocks:
The DSPs
Each DSP in the DSP block is connected to three data
buses: two buses that connect each DSP to the other
functional blocks and one that handles data transfer between
the DSPs (the zHop Bus). This architecture facilitates fast
DSP-to-off-chip data handling.
Each standard DSP is connected to 64 MB SDRAM and
each core in a QZDSP is connected to 256 MB DDR2.
Large and complex circuits should be designed to balance
memory needs (such as data buffers and filter coefficients)
across processors.
When designing circuits also note that the maximum number
of components for each RZ6 standard RZDSP is 768 and
1000 for each QZDSP.
The zBus Interface
The zBus interface provides a connection to the PC. Data
and host PC control commands are transferred to and from
the DSP Block through the zBus Interface Bus.
The I/O Interface
The I/O interface serves as a connection to outside signal
sources or output devices. It is used to input data from the
optional preamplifier input and digital and analog channels.
The I/O interface bus provides a direct connection to each
Distributing Data Across DSPs
To take advantage of multi-DSP modules, processing tasks must be efficiently
distributed across the available DSPs (or among cores of a quad-core DSP). The
RZ6 architecture provides the zHop bus for transferring data across DSPs.
The zHop Bus
The zHop bus allows the transfer of single or multi-channel signals between each
DSP in the RZ6.
In RPvdsEx, data is transferred across the zHop bus using paired zHop components,
including zHopIn, zHopOut, MCzHopIn, MCzHopOut, and MCzHopPick. Up to 126
pairs can be used in a single RPvdsEx circuit. Bus Related Delays
The zHop Bus introduces a two sample delay. This delay is taken care of for the
user in Synapse, BiosigRZ, and in OpenEx (when Timing and Data Saving macros
are used).
RZ6 Multi I/O Processor
System 3
Functional Signal Flow Diagrams
The following diagrams illustrate how analog signals for channels A and B flow
through the RZ6 and its modules. For more information on analog input and output
see “Onboard Analog I/O and Optional Amplifier Input” on page 1-39.
The diagram to the below depicts the analog input flow for the RZ6.
Input signals for channel A are input either through the XLR input (Mic-A), the
audio jack input (Diff-A), or BNC (In-A). Input signals for channel B are input
through the BNC (In-B).
A switch located to the left of the gain control knob allows a single gain setting for
both channels to be applied or bypassed completely.
The diagram below depicts analog output flow through the RZ6.
Signals A and B flow out of the DAC and pass through the programmable and
manual attenuation modules prior to being output on the front panel BNC connectors
(Out-A and Out-B).
The signals for channels A and B are also passed to two stereo headphone output
ports labeled A&B and Mon. Individual stereo power amplifiers are used for the BNC
and stereo headphone outputs.
A single channel monitor speaker is connected either to signal A, signal B, or
disabled based on the monitor control switch setting. The monitor level knob controls
the sound level of both the stereo headphone jack labeled Mon and the monitor
Finally, if the electrostatic speaker driver is enabled via its switch, located on the
front panel, signals A and B are output from the mini-DIN ports located on the RZ6
front panel.
RZ6 Multi I/O Processor
System 3
RZ6 Features
Onboard Analog I/O and Optional Amplifier Input
The RZ6 is equipped with onboard analog I/O and may also include a fiber optic
port for Medusa preamplifier input.
The following table provides a quick overview of the analog I/O and amplifier input
features and how they must be accessed during circuit design. The RZ6 relies
exclusively on macros for configuring analog and digital I/O and its fiber optic input
port. See the RPvdsEx Manual for more information on circuit design.
Analog I/O
Required Macro
A Inputs
Analog Input
A and B
DAC Outputs
Analog Output
A and B
Optical Amp
Medusa PreAmp Input
Onboard Analog Inputs
The RZ6 is equipped with two channels of 24-bit sigma-delta A/D converters. See
“RZ6 Multi I/O Technical Specifications” on page 1-45, for more information.
Analog signals can be input through several connectors on the RZ6 front panel.
Channel A has three possible sources:
MIC-A (XLR microphone input)
DIFF-A (1/4” TRS microphone input)
BNC labeled In-A
Channel B uses only the BNC labeled In-B:
Use only one input for channel A at a time. Attempting to input signals from multiple
sources will produce an erroneous signal.
Analog input is accessed in RPvdsEx through the RZ6_AudioIn macro.
RZ6 Multi I/O Processor
System 3
A and B Microphone Amplifier
An onboard two channel amplifier provides gain for the onboard analog input signals
(MIC-A, DIFF-A, In-A, and In-B). The switch located to the left of the gain
control knob allows the current gain setting to be applied (if set to Amp) or
bypassed completely (if set to Byp).
When the gain is enabled, analog input signals MIC-A and DIFF-A are differential.
Since the differential signals are summed a signal gain of 6 dB will be inherently
applied. If the amplifier is bypassed, common mode rejection is disabled.
To prevent clipping caused by a DC offset, the amplifier is AC coupled when the
gain amplification is in use.
The front panel gain control knob can be used to the
control overall signal level of both channels from 20 to
65 dB in 5 dB steps.
Fiber Optic Port ‐ Optional
The RZ6-A-P1 acquires digitized signals from a Medusa preamplifier over a fiber
optic cable. The port can be used with the RA4PA to input up to 4 channels.
Input from the preamplifier fiber optic port
is accessed using the RZ6_AmpIn macro.
The fiber optic port (devices with serial
number 1007 and greater) can also
support the HTI3 Head Tracker Interface.
Fiber Oversampling (acquisition only)
Signals are digitized on the Medusa preamplifier at a maximum sampling rate of ~25
kHz, however, the fiber optic port on the RZ6 can oversample the digitized signals
up to 8X or ~200 kHz. This will allow the RZ6 to run a DSP chain at ~200 kHz
and still sample data acquired through an optically connected preamplifier.
Oversampling is performed on the RZ6. The signals being acquired will still be
sampled at ~25 kHz on the preamplifier. This means that, even with oversampling,
signals acquired by an optically connected preamplifier are still governed by the
bandwidth and frequency response of the preamplifier.
Onboard Analog Outputs
The RZ6 is equipped with two channels of 24bit sigma-delta D/A converters (see “RZ6
Multi I/O Technical Specifications” on
page 45). Analog signals are output through a
variety of connectors on the RZ6 front panel.
Analog output is configured in RPvdsEx through
the RZ6_AudioOut macro.
RZ6 Multi I/O Processor
System 3
Programmable Attenuation
The RZ6_AudioOut macro provides access to two channels of programmable
attenuation for precision control of analog output signal levels over a wide dynamic
Programmable attenuation in the RZ6 is achieved using both analog and digital
attenuation methods. The device supports analog attenuation values of 0, 20, 40,
and 60 dB. Attenuation values which lie in-between or exceed 60 dB are handled
using digital attenuation.
For example, if you set an attenuation value of 66 dB in the RZ6_AudioOut macro,
the analog attenuator will be set to 60 dB and the remaining 6 dB of attenuation
will be applied by scaling the digital signal through RPvdsEx.
For the best results, you should utilize the maximum D/A voltage range and use the
RZ6_AudioOut macro to configure the desired attenuation setting for channels A and
Manual Attenuator
The RZ6 includes another level of analog attenuation that
can be controlled manually via the attenuator control knob
from 0 to 27 dB in increments of 3 dB.
Manual attenuation is applied to both channels before the
signals are output on any of the front panel connectors and
is therefore applied in addition to any programmable
attenuation set in RPvdsEx through the RZ6_AudioOut macro.
Analog Output via BNCs
DAC channels A and B are output to BNCs labeled Out-A
and Out-B after attenuation has been applied. These outputs
use a stereo power amplifier to drive TDT’s MF1 multifunction speakers.
A single signal generated or input from any of the RZ6 analog inputs can be ganged
to reduce the spectral variation in power of the transducer across all frequencies
(see “D/A Power Output Diagram” on page 1-47). To do this, configure your
signal to output from both DAC channels as shown in the following diagram.
Configure your RPvdsEx circuit to output the same signal to DAC channels A and B
then connect the transducer as shown in the diagram above.
RZ6 Multi I/O Processor
System 3
Stereo Headphone Output
DAC channels A and B are also available as a stereo headphone output through two
1/8” audio jack connector ports (channel A is the left stereo output and channel B
is the right stereo output). The port labeled A&B (top) provides a stereo
headphone output suitable for experimental paradigms while the port labeled Mon
(bottom) can be controlled by the Mon Level knob located directly to the right,
making it more suitable for monitoring the experiment.
All outputs use stereo power amplifiers
Monitor Speaker
The RZ6 is equipped with an onboard monitor
speaker, provided for audio monitoring of a single
channel. A switch located directly to the left of
the monitor speaker is used to select between
DAC channels A and B or to disable the monitor
speaker. The monitor speaker output level is controlled by the Mon Level knob
located directly to the right of the monitor stereo output.
Electrostatic Speaker Output
An onboard two channel broadband electrostatic
speaker driver is provided, allowing direct connection
of TDT's ES series electrostatic speakers. The driver
produces flat frequency responses reaching far into
the ultrasonic range, can drive two ES series
speakers, and is powered using the onboard power
supply. A switch located directly to the left of the
two 4-pin, mini-DIN connectors is used to enable or disable output of DAC channels
A and B.
The electrostatic speaker driver is designed to work exclusively with TDT’s
electrostatic series speakers. Do NOT attempt to use any other speaker.
If the electrostatic speaker driver is not being used, make sure that the ON/OFF
switch is in the OFF position to reduce noise on the RZ6.
Digital I/O Current RZ6 models are equipped with 24 bits of programmable digital I/O divided
into three bytes (A, B, and C) as described in the chart below. Earlier versions
RZ6 Multi I/O Processor
System 3
(serial number < 2000) were limited to 8 bits. By default, all lines are configured
as inputs.
Data direction is configured using the
RZ6_Control macro in RPvdsEx and may
be controlled dynamically through the
macro input port. For more information on
using the RZ6_Control macro see the help
provided in the macro's properties dialog
Digital I/O
Byte A
bits 0 - 7
byte addressable
Byte B
bits 0 - 7
byte addressable
Byte C
bits 0 – 7
bit addressable
The Digital I/O connector can be found on the front of the RZ6. See “RZ6 Multi
I/O Technical Specifications” on page 1-45, for pinout.
Voltage outputs and logic thresholds vary by type as shown in the table below.
Digital I/O Type
Voltage Output
Voltage Input
logic high
logic low
logic high
logic low
byte addressable
5 V
0 V
≥ 2.5 V
0 - 2.45 V
bit addressable
3.3 V
0 V
≥ 1.5 V
0 - 1.4 V
See “Working with BitIn - BitOut” in the “Digital I/O Circuit Design” section of the
RPvdsEx Manual for more information on programming and addressing Byte C of the
digital I/O. See “Working with WordIn -WordOut” in the “Digital I/O Circuit Design”
section of the RPvdsEx Manual for more information on programming and addressing
Bytes A and B of the digital I/O.
DSP Status Displays The RZ6 includes status lights and a VFD (Vacuum Fluorescent Display) screen to
report the status of the individual processors.
Status Lights
LEDs report the status of the multiprocessor's individual DSPs and will be lit solid
green when the corresponding DSP is installed and running. The LED will be lit dim
green if the cycle usage on a DSP is 0%. If the demands on a DSP exceed 99%
of its capacity on any given cycle, the corresponding LED will flash red (~1 time
per second). For QZDSPs, the LED represents the highest core cycle usage.
RZ6 Multi I/O Processor
System 3
The status lights flash when a DSP goes over the cycle usage limit, even if only for
a cycle. This helps identify periodic overages caused by components in time slices.
Front Panel VFD Screen
The front panel VFD screen reports detailed information about the status of the
system. The display includes two lines. The top line reports the system mode, Run!,
Idle, or Reset, and displays heading labels for the second line. The second line
reports the user’s choice of status indicators for each DSP followed by an aggregate
The user can cycle through the various status indicators using the Mode button to
the bottom right of the display. Push and release the button to change the display
or push and hold the button for one second then release to automatically cycle
through each of the display options. The VFD screen may also report system status
such as booting status (Reset).
When burning new microcode or if the firmware on the RZ6 is blank, the VFD
screen will report a cycle usage of 99% and the processor status lights flashes red.
Status Indicators
cycle usage; for QZDSPs, the highest core cycle usage is shown
Note: limited to 2 digits; ex: 110 displayed as 10.
percentage of internal device's bus capacity used
percentage of data transfer capacity used
Displays the current analog attenuator setting. Also displays bars
according to the RMS level of DAC A and B using a logarithmic
Note: Eight solid bars denote that the signal on DAC A or B is
Displays bars according to the RMS Level on A A and B using
a logarithmic scale.
Note: Eight solid bars denote that the signal on A A or B is
Analog Input – A LED Indicators
The A LED indicators are labeled and located at the top right of the RZ6 front
panel. The LEDs indicate the level of the signals on A channels A and B. This
provides a useful indicator for adjusting the gain and to detect and prevent clipping.
The following table describes the LED indicators' operation.
RZ6 Multi I/O Processor
System 3
Light Pattern
s Lit
Input is ≤ -6 dB down from max input voltage
Input is between -6 dB and -12 dB down from max input voltage
Input is between -12 dB and -25 dB down from max input voltage
Input is between -25 dB and -50 dB down from max input
Digital I/O LED Indicators
The digital I/O LED indicators are located directly below the VFD and DSP status
LEDs and display information relative to the digital I/O contained on the RZ6. There
are 8 LEDs one for each bit addressable digital I/O channel (Byte C). Each LED
may display one of four states. The following table illustrates the possible display
options and their associated descriptions.
Light Pattern
Dim Green
Bit is configured for output and is currently a logical low (0)
Solid Green
Bit is configured for output and is currently a logical high (1)
Dim Red
Bit is configured for input and is currently a logical low (0)
Solid Red
Bit is configured for input and is currently a logical high (1)
Analog Input ‐ Fiber Optic Port LED Indicator
A single green LED indicator is provided for the fiber optic input port on the RZ6A-P1. When lit the LED signifies a Medusa preamplifier is correctly synced with the
RZ6 Multi I/O Technical Specifications
The RZ6 can be equipped with a fiber optic input port and used with a four channel
Medusa preamplifier. See the preamplifier's technical specifications for A/D converters.
Up to four standard and/or quad-core
Standard: 400 MHz DSPs, 2.4 GFLOPS peak per DSP
Quad-Core: four 400 MHz DSPs, 2.4 GFLOPS per core
64 MB SDRAM per standard DSP
256 MB DDR2 RAM per core, four cores per QZDSP
2 channels, 24-bit sigma-delta
Sample Rate
Up to 195312.50 Hz
RZ6 Multi I/O Processor
System 3
Frequency Response
DC - 0.44*Fs (Fs=sample rate)
Voltage Out
+/- 10.0 Volts
S/N (typical)
115 dB (20 Hz - 80 kHz at 5 Vrms)
THD (typical)
Sample Delay
-90 dB (1 kHz output at 5 Vrms)
31 (Serial numbers > 2000)
47 (Serial numbers < 2000)
2 channels, 24-bit sigma-delta
Sample Rate
Frequency Response
Voltage In
S/N (typical)
THD (typical)
Sample Delay
Up to 195312.50
DC - 0.44*Fs (Fs=sample rate)
+/- 10.0 Volts
115 dB (20 Hz - 80 kHz at 5 Vrms)
-90 dB (1 kHz output at 5 Vrms)
66 samples
Fiber Optic Ports
Optional Input Available on RZ6-A-P1 only
Supports 4-channel Medusa preamplifier or HTI3 Head
Tracker Interface (serial number 1007 and greater)
Digital I/O
8 programmable bits: 3.3 V, 25 mA max load
2 programmable bytes (16 bits): 5.0 V, 35 mA max
A and B Microphone Amplifier
Single setting for both channels (AC coupled when
High Pass Corner Frequency
Gain Settings
Gain Step Size
Programmable Attenuation
Switching Time
Settling Time
Transient Voltage
3.6 Hz (Active only if the Amplifier is enabled)
20 to 65 dB
5 dB
2 channels
1 sample
3 μsec
~370 mV
Hardware Attenuation Settings
0, 20, 40, 60 dB
Manual Attenuation
Single setting for both channels
Attenuation Settings
Attenuation Step Size
RZ6 Multi I/O Processor
0 to 27 dB
3 dB
2 channels
System 3
Spectral Variation
Signal Noise
Noise Floor
Input Impedance
Output Impedance
Headphone Output
Output Impedance
Electrostatic Speaker Output
< 0.1 dB from 50 Hz to 200 kHz
115 dB (20 Hz to 80 kHz)
< 0.02% at 1 Watt from 50 Hz to 100 kHz
20 μV rms
10 kOhm
1 Ohm
0.5 Ohm ganged
2 channels
1 Ohm
2 channels
Note: For further information on speaker specifications,
“EC1 Technical Specifications” on page 16-12.
D/A dB Rolloff Diagram
This graph shows the dB rolloff for the RZ6 with varying sampling frequencies for the
D/A. The sample delay remains constant for varying frequencies.
D/A Power Output Diagram
This graph shows the power output for the RZ6 with varying driving frequencies for
the D/As when driving a four Ohm load. Driving higher impedance loads will reduce
spectral variation.
RZ6 Multi I/O Processor
System 3
DB25 Digital I/O Pinout
RZ6 Multi I/O Processor
Byte C
Bit Addressable digital
Bits 0, 2, 4, and 6
Digital I/O Ground
Byte A
Word addressable digital
Bits 1, 3, 5, and 7
Byte B
Word addressable digital
Bits 1, 3, 5, and 7
Byte C
Bit Addressable digital
Bits 1, 3, 5, and 7
Byte A
Word addressable digital
Bits 0, 2, 4, and 6
Byte B
Word addressable digital
Bits 0, 2, 4, and 6
System 3
Digital I/O – DB9 Connector Pinout Note:
Serial numbers < 2000 only.
Digital I/O
0, 2, 4, 6
Digital I/O
bits 1, 2, 3, 5, 7
RZ6 Multi I/O Processor
RZ6 Multi I/O Processor
System 3
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