Mark Pizzolato 6831746400 All VAX: Clarify Opcode Table decode values ...

the opcode table first word consists of bits:

<7> = FPD is legal for this opcode.
<4:6> = number of specifiers for unimplemented opcodes (VAX subsets)
<3> = unused
<0:2> = number of specifiers

The mask used to be 0x70. The convention is that x_M_y is a mask value
<right-justified>, for a macro like:

#define get_foo(x)        (((x) >> x_V_foo) & x_M_foo)

For a subset VAX (like the 3900), the unimplemented opcodes are those

2017-03-20 08:10:43 -07:00

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