GS8662S08E GSI [GSI Technology], GS8662S08E Datasheet - Page 29

• Manufacturer Part Number: GS8662S08E
• Description: 72Mb Burst of 2 DDR SigmaSIO-II SRAM
• Manufacturer: GSI [GSI Technology]

When the TAP controller is placed in Capture-IR state the two least significant bits of the instruction register are loaded with 01.
When the controller is moved to the Shift-IR state the Instruction Register is placed between TDI and TDO. In this state the desired
instruction is serially loaded through the TDI input (while the previous contents are shifted out at TDO). For all instructions, the
TAP executes newly loaded instructions only when the controller is moved to Update-IR state. The TAP instruction set for this
device is listed in the following table.
Instruction Descriptions
BYPASS
SAMPLE/PRELOAD
Rev: 1.01 9/2005
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com.
When the BYPASS instruction is loaded in the Instruction Register the Bypass Register is placed between TDI and TDO. This
occurs when the TAP controller is moved to the Shift-DR state. This allows the board level scan path to be shortened to facili-
tate testing of other devices in the scan path.
SAMPLE/PRELOAD is a Standard 1149.1 mandatory public instruction. When the SAMPLE / PRELOAD instruction is
loaded in the Instruction Register, moving the TAP controller into the Capture-DR state loads the data in the RAMs input and
I/O buffers into the Boundary Scan Register. Boundary Scan Register locations are not associated with an input or I/O pin, and
are loaded with the default state identified in the Boundary Scan Chain table at the end of this section of the datasheet. Because
the RAM clock is independent from the TAP Clock (TCK) it is possible for the TAP to attempt to capture the I/O ring contents
while the input buffers are in transition (i.e. in a metastable state). Although allowing the TAP to sample metastable inputs will
not harm the device, repeatable results cannot be expected. RAM input signals must be stabilized for long enough to meet the
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Test Logic Reset
Run Test Idle
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1
JTAG Tap Controller State Diagram
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1
Capture DR
Update DR
Pause DR
Select DR
Exit1 DR
Shift DR
Exit2 DR
0
0
1
1
0
1
0
GS8662S08/09/18/36E-333/300/250/200/167
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0
0
0
1
1
1
Capture IR
Update IR
Pause IR
Select IR
Exit1 IR
Shift IR
Exit2 IR
0
1
1
0
1
0
0
© 2005, GSI Technology
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Preliminary