
AMD-K5 Processor
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21062E/0—June 1997
AMD K86 Family BIOS and Software Tools Developers Guide
Preliminary Information
The Functional-Redundancy Checking mode can only be exited
by the assertion of RESET. Functional-redundancy checking
cannot be performed in the Hardware Debug Tool (HDT) mode.
The assertion of FRCMC is not recognized while PRDY is
asserted.
Boundary Scan Architecture Support
The AMD-K5 processor provides test features compatible with
the Standard Test Access Port (TAP) and Boundary Scan Test
Architecture as defined in the IEEE 1149.1-1990 JTAG
Specification. The subsections in this topic include:
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Boundary Scan Test Functional Description
Boundary Scan Architecture
Registers
The Test Access Port (TAP) Controller
JTAG Register Organization
JTAG Instructions
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The external TAP interface consists of five pins:
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TCK: The Test Clock input provides the clock for the JTAG
test logic.
TMS: The Test Mode Select input enables TAP controller
operations.
TDI: The Test Data Input provides serial input to registers.
TDO: The Test Data Output provides serial output from the
registers; the signal is tri-stated except when in the Shift-DR
or Shift-IR controller states.
TRST: The TAP Controller Reset input initializes the TAP
controller when asserted Low.
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The internal JTAG logic contains the elements listed below:
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The Test Access Port (TAP) Controller
—Decodes the inputs
on the Test Mode Select (TMS) line to control test
operations. The TAP is a general-purpose port that provides
access to the test support functions built into the AMD-K5.
Instruction Register—Accepts instructions from the Test
Data Input (TDI) pin. The instruction codes select the
specific test or debug operation to be performed or the test
data register to be accessed.
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