Compaq EV68A specifications SysVref Domain SysAddInL140

21264/EV68A Signal Names and Functions

Table 3–3 21264/EV68A Signal Descriptions by Function (Continued)

Signal	Type	Count	Description
BcVref	I_DC_REF	1	Tag data input reference voltage.
SysVref Domain
SysAddIn_L[14:0]	I_DA	15	Time-multiplexed SysAddIn, system-to-21264/EV68A.
SysAddInClk_L	I_DA	1	Single-ended forwarded clock from system for
			SysAddIn_L[14:0] and SysFillValid_L.
SysAddOut_L[14:0]	O_OD	15	Time-multiplexed SysAddOut, 21264/EV68A-to-system.
SysAddOutClk_L	O_OD	1	Single-ended forwarded-clock.
SysCheck_L[7:0]	B_DA_OD	8	Quadword ECC check bits for SysData_L[63:0].
SysData_L[63:0]	B_DA_OD	64	Data bus for memory and I/O data.
SysDataInClk_H[7:0]	I_DA	8	Single-ended system-generated clocks for clock forwarded
			input system data.
SysDataInValid_L	I_DA	1	When asserted, marks a valid data cycle for data transfers to
			the 21264/EV68A.
SysDataOutClk_L[7:0]	O_OD	8	Single-ended 21264/EV68A-generated clocks for clock for-
			warded output system data.
SysDataOutValid_L	I_DA	1	When asserted, marks a valid data cycle for data transfers
			from the 21264/EV68A.
SysFillValid_L	I_DA	1	Validation for fill given in previous SysDC command.
SysVref	I_DC_REF	1	System interface reference voltage.
Clocks and PLL
ClkIn_H	I_DA_CLK	2	Differential input signals provided by the system.
ClkIn_L
EV6Clk_H	O_PP_CLK	2	Provides an external test point to measure phase alignment of
EV6Clk_L			the PLL.
FrameClk_H	I_DA_CLK	2	A skew-controlled differential 50% duty cycle copy of the
FrameClk_L			system clock. It is used by the 21264/EV68A as a reference,
			or framing, clock.
PLL_VDD	2.5 V	1	2.5-V dedicated power supply for the 21264/EV68A PLL.
MiscVref Domain
ClkFwdRst_H	I_DA	1	Systems assert this synchronous signal to wake up a powered-
			down 21264/EV68A. The ClkFwdRst_H signal is clocked
			into a 21264/EV68A register by the captured FrameClk_x
			signals.
DCOK_H	I_DA	1	dc voltage OK. Must be deasserted until dc voltage reaches
			proper operating level. After that, DCOK_H is asserted.
IRQ_H[5:0]	I_DA	6	These six interrupt signal lines may be asserted by the system.
MiscVref	I_DC_REF	1	Reference voltage for miscellaneous pins.
PllBypass_H	I_DA	1	When asserted, this signal will cause the input clocks
			(ClkIn_x) to be applied to the 21264/EV68A internal circuits,
			instead of the 21264/EV68A’s global clock (GCLK).

21264/EV68A Hardware Reference Manual Hardware Interface 3–7