29 September 1997 – Subject To Change
Privileged Architecture Library Code
6–7
Required PALcode Function Codes
6.5 Required PALcode Function Codes
Table 6–2 lists opcodes required for all Alpha implementations. The notation used is
oo.ffff, where oo is the hexadecimal 6-bit opcode and ffff is the hexadecimal 26-bit
function code.
6.6 21164PC Implementation of the Architecturally Reserved
Opcodes
PALcode uses the Alpha instruction set for most of its operations. Table 6–3 lists the
opcodes reserved by the Alpha architecture for implementation-specific use. These
opcodes are privileged and are only available in PALmode.
MCHK
0400
Uncorrected hardware error
OPCDEC
0480
Illegal opcode
ARITH
0500
Arithmetic exception
FEN
0580
Floating-point operation attempted with:
Table 6–2 Required PALcode Function Codes
Mnemonic
Type
Function Code
DRAINA
Privileged
00.0002
HALT
Privileged
00.0000
IMB
Unprivileged
00.0086
Table 6–1 PALcode Trap Entry Points
(Sheet 2 of 2)
Entry Name
Offset
16
Description
•
Floating-point instructions (LD, ST, and
operates) disabled through FPE bit in the
ICSR IPR
•
Floating-point IEEE operation with data type
other than S, T, or Q