Instruction manual

Component Address Length Description
Flags Base + 90
16
4 Bytes A 4-byte field with bit<0> indicating
whether this module implements parity.
A 1 in bit<0> means that this option
supports TURBOchannel parity. All
remaining bits are reserved and should
remain zero.
ROM Objects Base +
A0
16
Variable
size
The data structures that provide
information about a section of code
or data in the ROM. The first ROM
object in both the System ROM and the
I/O ROM contains all the code that is
present in the ROM. This facilitates the
loading of the system ROM by the serial
ROM on powerup. Subsequent ROM
objects describe areas of the FLASH
ROM that can be written.
Figure 16 shows the format of a ROM object.
Figure 16 Format of a ROM Object
0x00
0x04
0x08
0x14
MR−0139−93RAGS
Name
Body
Length
Rgn
VersionType
000812161831
The components of the ROM object are:
Component Address Length Description
Version ROM object base (bits
<7:0>)
8 bits Contains the ROM object
version number.
Type ROM object base (bits
<11:8>)
4 bits Indicates the object body type.
For the I/O and system ROM
this type value is always 1,
indicating ALPHA code.
Region ROM object base (bits
<17:16>)
2 bits This field is unused in the
system and I/O ROMs; it is
used in MIPS TURBOchannel
systems. It contains 0.
DEC 3000 AXP Firmware ROMs 13–5