Instruction manual

14
Powerup Initialization and Firmware Entry
When you power up the DEC 3000 AXP, the serial ROM code is loaded into the
CPU’s 8 KB instruction cache. Serial ROM (SROM) code verifies the functionality
of the hardware required to load and execute the system ROM code, which
contains the PAL machine initialization and console code.
After the Icache is loaded, the SROM data and clock lines are used to establish a
serial-line connection to the CPU. An EIA adapter module provides the interface
to terminal devices. SROM diagnostic output is sent to this serial port and to the
LEDs. Serial-port speed is 19.2K baud in 300 models and 9600 baud in other
models. If the SROM code encounters a fault that would obviate loading and
executing system ROM code, power-on execution is halted and a branch is made
to the SROM mini-console routine.
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This chapter covers the following topics:
• Power-on initialization flow (Section 14.1)
• Power-on output (Section 14.2)
• Map of memory following power-on initialization (Section 14.3)
• Machine state following power-on initialization (Section 14.4)
• System firmware entry (Section 14.5)
14.1 Power-On Initialization Flow
Figure 17 shows the power-on initialization flow. Table 47 lists the execution
sequence of SROM code and the corresponding LED codes on 400/500/600/700
/800/900 models. Table 46 lists the execution sequence of SROM code and the
corresponding LED codes on 300 models.
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The mini-console is for Digital use only.
Powerup Initialization and Firmware Entry 14–1