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IBM21P100BGB
IBM 133 PCI-X Bridge R1.1
JTAG Boundary Scan
Page 112 of 131
ppb11_jtag.fm.03
July 9, 2001
9.3 Bypass Register
The Bypass register is a 1-bit shift register that provides a single bit scan path between the JTG_TDI input
and JTG_TDO output. This abbreviated scan path is selected by the BYPASS instruction code and is used to
shorten the overall scan ring length during board-level testing when the bridge is not involved.
9.4DeviceIDRegister
The Device Identification register, defined by IEEE Standard 1149.1, identifies IBM as the manufacturer of
the IBM 133 PCI-X Bridge R1.1 and provides a portion of the die part number and a revision code for the
device, as follows:
9.5 Boundary-Scan Register
The Boundary-Scan register is formed by connecting boundary-scan cells placed at the device’ssignalpins
into a shift register path. The input to the shift register is the JTG_TDI signal and the output from the shift
register is the JTG_TDO signal. When selected and controlled properly by the TAP Controller, this structure
provides the output drive and input observability features necessary for effective boundary-scan testing.
Several varieties of boundary-scan cells are possible, selected according to the function of the signal pin with
which they are associated:
Width
32 bits
Access
Read only
Reset Value
x‘1490049’
Version
Part Number
Manufacturer ID
Fi
x
e
d
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9876543210
Bits
Access
Field Name and Description
31:28
RO
Version number of the device.
27:12
RO
Last four hex digits of the BEOL die part number.
11:1
RO
JEDEC-assigned identifier for manufacturer (IBM)
0
RO
Fixed bit equal to b‘1’
Input-only pins:
For device inputs that are not shared with component test functions, the boundary-
scan cell “IBM1149_BSR_BIDIIN” is used. Inputs that are shared with component
test functions use the “IBM1149_BSR_IN” boundary-scan cell. Both have the
BSDL function label of “INPUT”.