Specifications

System Macros Invoked by Drivers
REQALT
REQALT
Obtains a set of Q22–bus alternate map registers.
Format
REQALT
Description
The REQALT macro calls IOC$REQALTMAP to obtain a set of Q22–bus alternate
map registers (registers 496 to 8191). When the REQALT macro is invoked, the
following registers must contain the following values:
Register Contents
R5 Address of UCB
00(SP) Address of caller’s caller
The REQALT macro destroys the contents of R0 through R2.
2–58