Electrical Specifications
2.6
Front Side Bus Signal Groups
The front side bus signals are grouped by buffer type as listed in Table 2-5. The buffer type
indicates which AC and DC specifications apply to the signals. AGTL+ input signals have
differential input buffers that use GTLREF as a reference level. In this document, the term “AGTL+
Input” refers to the AGTL+ input group as well as the AGTL+ I/O group when receiving. Similarly,
“AGTL+ Output” refers to the AGTL+ output group as well as the AGTL+ I/O group when driving.
AGTL+ asynchronous outputs can become active anytime and include an active pMOS pull-up
transistor to assist during the first clock of a low-to-high voltage transition.
Implementing a source synchronous data bus requires specifying two sets of timing parameters.
One set is for common clock signals which are dependent upon the rising edge of BCLK0 (ADS#,
HIT#, HITM#, etc.). The second set is for the source synchronous signals that are relative to their
respective strobe lines (data and address) as well as the rising edge of BCLK0. Asynchronous
signals are present (A20M#, IGNNE#, etc.) and can become active at any time during the clock
cycle. Table 2-5 identifies signals as common clock, source synchronous, and asynchronous.
Table 2-5. Front Side Bus Pin Groups (Sheet 1 of 2)
Signal Group
Type
Signals1
BPRI#, BR[3:1]#, DEFER#, ID[7:0]#, IDS#,
OOD#, RESET#, RS[2:0]#, RSP#, TRDY#
AGTL+ Common Clock Input
Synchronous to BCLK[1:0]
ADS#, AP[1:0]#, BINIT#, BNR#, BPM[5:0]#,
BR0#, DBSY#, DP[3:0]#, DRDY#, HIT#,
HITM#, LOCK#, MCERR#
AGTL+ Common Clock I/O
Synchronous to BCLK[1:0]
Signals
Associated Strobe
REQ[4:0]#,
A[37:36,16:3]#
ADSTB0#
A[39:38,35:17]#
ADSTB1#
D[15:0]#, DEP[1:0]#,
DBI0#
AGTL+ Source Synchronous
I/O
Synchronous to associated
strobe
DSTBP0#, DSTBN0#
D[31:16]#, DEP[3:2]#,
DBI1#
DSTBP1#, DSTBN1#
DSTBP2#, DSTBN2#
DSTBP3#, DSTBN3#
D[47:32]#, DEP[5:4]#,
DBI2#
D[63:48]#, DEP[7:6]#,
DBI3#
AGTL+ Strobe Input/Output
Synchronous to BCLK[1:0]
ADSTB[1:0]#, DSTBP[3:0]#, DSTBN[3:0]#
FERR#/PBE#, IERR#, PROCHOT#
AGTL+ Asynchronous Output Asynchronous
A20M#, FORCEPR#, IGNNE#, INIT#, LINT0/
INTR, LINT1/NMI, SMI#, STPCLK#
GTL+ Asynchronous Input
Asynchronous
GTL+ Asynchronous Output
TAP Input
Asynchronous
THERMTRIP#
TCK, TDI, TMS
TRST#
Synchronous to TCK
Asynchronous
TAP Input
TAP Output
Synchronous to TCK
TDO
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