GS881Z18T GSI [GSI Technology], GS881Z18T Datasheet - Page 27

• Manufacturer Part Number: GS881Z18T
• Description: 8Mb Pipelined and Flow Through Synchronous NBT SRAMs
• Manufacturer: GSI [GSI Technology]

EXTEST
IDCODE
SAMPLE-Z
RFU
JTAG TAP Instruction Set Summary
Rev: 1.10 8/2000
Specifications cited are subject to change without notice. For latest documentation see http://www.gsitechnology.com
Notes:
1.
2.
Instruction
SAMPLE-Z
Register. 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 con-
tents 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 TAPs input data cap-
ture set-up plus hold time (tTS plus tTH ). The RAMs clock inputs need not be paused for any other TAP operation except capturing the I/O
ring contents into the Boundary Scan Register. Moving the controller to Shift-DR state then places the boundary scan register between the
TDI and TDO pins. Because the PRELOAD portion of the command is not implemented in this device, moving the controller to the Update-
DR state with the SAMPLE / PRELOAD instruction loaded in the Instruction Register has the same effect as the Pause-DR command. This
functionality is not Standard 1149.1-compliant.
EXTEST is an IEEE 1149.1 mandatory public instruction. It is to be executed whenever the instruction register, whatever length it may be in
the device, is loaded with all logic 0s. EXTEST is not implemented in this device. Therefore, this device is not 1149.1-compliant. Neverthe-
less, this RAM’s TAP does respond to an all zeros instruction, as follows. With the EXTEST (000) instruction loaded in the instruction regis-
ter the RAM responds just as it does in response to the BYPASS instruction described above.
The IDCODE instruction causes the ID ROM to be loaded into the ID register when the controller is in Capture-DR mode and places the ID
register between the TDI and TDO pins in Shift-DR mode. The IDCODE instruction is the default instruction loaded in at power up and any
time the controller is placed in the Test-Logic-Reset state.
If the SAMPLE-Z instruction is loaded in the instruction register, all RAM outputs are forced to an inactive drive state (high-Z) and the Bound-
ary Scan Register is connected between TDI and TDO when the TAP controller is moved to the Shift-DR state.
These instructions are Reserved for Future Use. In this device they replicate the BYPASS instruction.
PRELOAD
Instruction codes expressed in binary, MSB on left, LSB on right.
Default instruction automatically loaded at power-up and in test-logic-reset state.
SAMPLE/
IDCODE
EXTEST
BYPASS
RFU
RFU
GSI
Code
000
001
010
011
100
101
110
111
Replicates BYPASS instruction. Places Bypass Register between TDI and TDO.
This RAM does not implement 1149.1 EXTEST function. *Not 1149.1 Compliant *
Preloads ID Register and places it between TDI and TDO.
Captures I/O ring contents. Places the Boundary Scan Register between TDI and TDO.
Forces all RAM output drivers to High-Z.
Do not use this instruction; Reserved for Future Use.
Replicates BYPASS instruction. Places Bypass Register between TDI and TDO.
Captures I/O ring contents. Places the Boundary Scan Register between TDI and TDO.
This RAM does not implement 1149.1 PRELOAD function. *Not 1149.1 Compliant *
GSI private instruction.
Do not use this instruction; Reserved for Future Use.
Replicates BYPASS instruction. Places Bypass Register between TDI and TDO.
Places Bypass Register between TDI and TDO.
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Description
GS881Z18/36T-11/100/80/66
© 1998, Giga Semiconductor, Inc.
Preliminary
Notes
1, 2
1
1
1
1
1
1
1
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