Service manual

System Overview 1-11
Alpha Chip Composition
The Alpha 21264 chip uses 0.35 micron chip technology, has a transistor count of 15.2
million, consumes 50 watts of power, and is air cooled (a fan is on the chip). The
default cache system is write-back.
Chip Description
Unit Description
Instruction 64-Kbyte I-cache
Execution 4-way execution; four integer units, two of which can perform
memory address calculations for load and store instructions;
dedicated units for floating-point add, multiply, divide, and
square root operations.
Memory Merge logic, 64-Kbyte write-through first-level data cache,
bus interface unit that consists of two ports, one a 16-byte B-
cache port and the other an 8-byte system port.
CPU Variants
Module Variant Clock Frequency Onboard Cache
KN310-Ax 500 MHz 4 Mbytes
CPU Configuration Rules
• The first CPU must be in CPU slot 0.
• Both CPUs must have the same Alpha chip clock speed selected.
Module LEDs
LED Name
Description (read LEDs from right to left on the
module)
2V_PWRGOOD_LED Normally on. Indicates the presence of 2.XV.
SROM_CLK_LED Normally off. Toggles on and off rapidly during the
SROM load phase.
DC_OK_LED Normally on. Indicates the presence of DC_OK.
CPU_SELF_TEST_LED Normally on. Indicates the status of self-test. If the LED
is off, there was an error or timeout after the SROM load.