Level Epsilon Architecture Support Reference Manual

Contents
Section 4. Interrupts
Virtual Segment Descriptor (VSD) ......................................................... 3–7
Untouched DD ...................................................................... 3–7
Unindexed (Original and Copy) DD ....................................... 3–7
IndexedDD (Indexed Data Descriptor .................................. 3–8
Code Segment Descriptor (CSD) ......................................... 3–9
Virtual Segments ................................................................................. 3–10
Virtual Index ......................................................................................... 3–11
References .......................................................................................... 3–12
Address Couples ................................................................ 3–12
Environment Links .............................................................. 3–13
Stuffed Indirect Reference Word (SIRW) ........................... 3–14
Program Control Word (PCW) ............................................ 3–14
Stack Structure and Linkage ................................................................ 3–15
Stack Frame Linkage .......................................................... 3–16
Top-of-Stack Linkage .......................................................... 3–17
Protected Object Word (POW) ............................................................ 3–18
Tag Values ........................................................................................... 3–19
Data Structure Access ......................................................................... 3–20
Interrupt Mechanism ............................................................................. 4–1
Superhalt .............................................................................. 4–1
Interrupt References ............................................................ 4–2
Vector Interrupt Formats ...................................................... 4–2
Code Stream Designation and Resumption ......................... 4–3
Interrupt Parameters ............................................................ 4–4
Restart Configuration ........................................................... 4–5
Operator Subdivision ............................................................ 4–5
Interrupt Definition ................................................................................. 4–6
Arithmetic Interrupts ............................................................ 4–7
Service Interrupts ............................................................... 4–10
Enforcement Interrupts ...................................................... 4–14
Alarm Interrupts (Libra 6xx and 7xx Systems) ................... 4–22
Asynchronous Interrupts .................................................... 4–26
External Interrupts .............................................................. 4–27
Maskable External Interrupts ............................................. 4–28
Interrupt Vector .................................................................................... 4–29
Section 5. Operator Set
General Information ............................................................................... 5–1
Operators and Code Streams ............................................... 5–1
Interrupts and Resumption .................................................. 5–3
Operator Applicability ........................................................... 5–4
Expression Stack Control ..................................................... 5–5
Stack-State Transformation .................................................. 5–6
Expression Stack Treatment of Word Extension ................. 5–7
Descriptor Interpretation ...................................................... 5–7
Computational Operators ...................................................................... 5–8
Numeric Operand Interpretation .......................................... 5–8
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