Struct SequenceFlags 

struct SequenceFlags {
    flag_values: u64,
    flag_changes: u64,
}

Flags represent requests to run for instruction sequences (today one might describe these as threads). Some sequences are special:

Sequence Number	Description
0	Sequence which is run to start the computer (e.g. when “CODABO” or “START OVER” is pressed).
41-75	hardware devices
76	Not for physical devices.
77	Not for physical devices.

The flag for sequences 76 and 77 may only be raised/lowered by program control.

The Lincoln Laboratory book “MIT Lincoln Laboratory: Technology in Support of National Security” states (on page 462) that The Xerox Alto also used sequences for I/O. See also https://en.wikipedia.org/wiki/Xerox_Alto#Architecture

Fields

flag_values: u64

flag_changes: u64

Implementations

impl SequenceFlags

fn new() -> SequenceFlags

fn lower_all(&mut self)

fn flagbit(flag: &SequenceNumber) -> u64

fn lower(&mut self, flag: &SequenceNumber)

fn raise(&mut self, flag: &SequenceNumber)

fn current_flag_state(&self, flag: &SequenceNumber) -> bool

fn highest_priority_raised_flag(&self) -> Option<SequenceNumber>

Return the index of the highest-priority (lowest-numbered) flag. If no flag is raised (the machine is in “Limbo”), return None.

fn drain_flag_changes(&mut self) -> Vec<SequenceNumber>

Trait Implementations

impl Debug for SequenceFlags

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.