大型机汇编HLASM调试工具XDC及基本概念理解之三home Address space VS primary address sapce
背景：今天翻看了多年前做过的大型机汇编项目，后来因为中美关系此项目就中断了。但在学习过程中有很多总结发布出来，希望对还在做这种项目的人有点帮助（很有可能全国都没几个了，大型机+汇编都是冷门）。
If a program is part of a subsystem that offers services to many users, it might want to set up addressability for programs executing in other address spaces to reference data in its address space. Figure 42 shows a subsystem's home address space as AS1. Setting up addressability to the home address space requires no action. The PC routines that run in address spaces AS2, AS3, and AS4 all run under the same TCB, that of PGM1. Addressability to AS1 is through the special ALET of two. PGM2, PGM3, and PGM4 can place the value 2 in an AR of a AR/GPR pair to reference data in the home address space.
Figure 42. Using the ALET for the Home Address Space
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下面是个例子:
注意 D R4! 与 D 7F438F10 的不同