Architecture Subsetting

MacVAX is a subset VAX processor as defined in the DIGITAL VAX Architecture Handbook. Architecture subsetting deals with those parts of the VAX architecture that must be provided as standard features of a processor, may be provided as options to the processor, or may be omitted completely from the processor.

The following optional instruction subsets have been omitted:


D_Floating Instructions
G_Floating Instructions
H_Floating Instructions
Decimal String Instructions

The following optional Charater String instructions have also been omitted:


CMPC3, CMPC5, CRC, MATCHC, MOVTC, MOVTUC, SCANC, SPANC.


MacVAX fails to implement the following Instructions from the Kernel subset:


INSQHI, INSQTI, REMQHI, REMQTI, EDIV, EMODF.


MacVAX does not support Compatibility Mode. Attempts to enter compatibilty mode generate a reserved operand fault.

MacVAX omits the PME Internal processor register. PME requests are ignored.