I ISystem Mask I Key I EMiP I 0 cc I Program I 0 II I I I I I Mask , II L---- __________________________________________________________________ o 7 8 11 12 15 16 17 18 19 20 23 24 311 I o Instruction Address II L- ______________________________________________________________________ 32 33 63
The fields of the PSi are:
18-19 24-32
Figure 47. Must be zero. PER (Program Event Recording) enabled. Must be zero.
Address translation. Summary I/O Summary extension.
The protection key determines if information can be stored
or fetched from a particular location.
Extended control mode.
The machine check flag is set to 1 if machine check
interruptions are enabled.
The wait state flag is set to 1 when the CPU is in the wait
The problem state flag is set to 1 when the CPU is
operating in the proble. rather than the supervisor
state. Must be zero.
The condition code reflects the result of a previous
arithmetic, logical, or I/O operation.
The program .ask indicates whether or not various program
exceptions are allowed to cause program interrupts. Must be zero.
The instruction address gives the location of the next
instruction to be executed for program interrupts or of
the instruction last executed for external interrupts.
The Extended Control PSi (Program Status Word) 348 IBM VM/370 System Programmer's Guide
Appendix B: M U
G MULTI-LEAVING is a term that describes a computer-to-computer communication technique developed for use by the HASP system and used by
the RSCS component of VM/310. MULTI-LEAVING can be defined as the fully
synchronized, pseudo-simultaneous, bidirectional transmission of a
variable number of data streams between two or more computers using
binary synchronous communications (BSC) facilities. MULTI-LEAVING in VM/370 The following sections outline the of a comnrehensive. MULTI-LEAVING comllunica tions system (;; - - HASP/ASP) :-. While VM/310 support for programmable BSC remote stations is completely
consistent with the MULTI-LEAVING design, it does not use certain of the
features provided in MULTI-LEAVING: The transmission of record types other than print, punch, input,
console, and control is not supported. The only general control record type used is the terminal sign-cn
control. Multiple data streams are not supported. Only SCB count units of 1 are used. No support is included for column binary cards. MULTI-LEAVING Philosophy The basic element for multileaved transmission is the character string. One or more character strings are formed from the smallest external element of transmission, the physical These physical records
are input to MULTI-LEAVING and may be any of the classic record types
(card images, printed lines, tape records, etc.]. For efficiency in
transmission, each of these data records is reduced to a series of character strings of two basic types:
1. A variable-length nonidentical series of characters (for example, SYZ123&1!) ---and---
2. A variable number of identical characters (for example,
An eight-bit control field# termed a String Control Byte (SCB), precedes each character string to identify the type and length of the
string. Thus, a string of nonidentical characters (as in 1 above) represented by an SCB followed by the nonduplicate characters. A strins of conse-cUtlve, - du-plica te, nonblank chara-cters(as in 1 -above) -can-- -be
represented by an SCB and a single character (the seB indicates the
duplication count, and the character following indicates the character
to be duplicated). In the case of an all-blank character string, only an SCB is required to indicate both the type and the number of blank
Appendix B: MULTI-LEAVING 349
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