Struct VMemory 

struct VMemory {

    a_register: Unsigned36Bit,
    b_register: Unsigned36Bit,
    c_register: Unsigned36Bit,
    d_register: Unsigned36Bit,
    e_register: Unsigned36Bit,
    m_register_metabit: bool,
    unimplemented_shaft_encoder: MemoryWord,
    unimplemented_external_input_register: MemoryWord,
    rtc: MemoryWord,
    rtc_start: Duration,
    codabo_start_point: [Unsigned36Bit; 8],
    plugboard: [Unsigned36Bit; 32],
    permit_unknown_reads: bool,
    sacrificial_word_for_unknown_reads: MemoryWord,
    sacrificial_metabit: bool,
}

The TX-2’s V-memory.

Metabits

Arithmetic registers have no meta bit. Accesses which attempt to read the meta bit of registers A, B, , D, E actually return the meta bit in the M register. This is briefly described on page 5-23 of the User Handbook.

It says,

The data reference metabit (M⁴˙¹⁰) can be detected only when set (just as N⁴˙¹⁰ above). Note that it can be changed without a memory reference for it serves as the metabit of the A, B, C, D, and E registers. (i.e., MKC₄.₁₀ A or MKC₄.₁₀ B will change bit 4.10 of M).“

V memory in general does behave as if it has a meta bit. For example, there is a push-button on the console that acts as the value of the meta bit of the shaft encoder register.

See also https://github.com/TX-2/TX-2-simulator/issues/59.

Fields

a_register: Unsigned36Bit

b_register: Unsigned36Bit

c_register: Unsigned36Bit

d_register: Unsigned36Bit

e_register: Unsigned36Bit

m_register_metabit: bool

unimplemented_shaft_encoder: MemoryWord

unimplemented_external_input_register: MemoryWord

rtc: MemoryWord

rtc_start: Duration

codabo_start_point: [Unsigned36Bit; 8]

plugboard: [Unsigned36Bit; 32]

permit_unknown_reads: bool

Writes to unknown locations are required to be ignored, but reads have to return a value. If permit_unknown_reads is set, a special value is returned. If not, a QSAL alarm will be raised (though that alarm may in turn be suppressed).

sacrificial_word_for_unknown_reads: MemoryWord

sacrificial_metabit: bool

Implementations

impl VMemory

fn new(ctx: &Context) -> VMemory

fn get_a_register(&self) -> Unsigned36Bit

fn get_b_register(&self) -> Unsigned36Bit

fn get_c_register(&self) -> Unsigned36Bit

fn get_d_register(&self) -> Unsigned36Bit

fn get_e_register(&self) -> Unsigned36Bit

fn set_a_register(&mut self, value: Unsigned36Bit)

fn set_b_register(&mut self, value: Unsigned36Bit)

fn set_c_register(&mut self, value: Unsigned36Bit)

fn set_d_register(&mut self, value: Unsigned36Bit)

fn set_e_register(&mut self, value: Unsigned36Bit)

fn read_access<'a>( &'a mut self, ctx: &Context, addr: &Address, ) -> Result<MemoryReadRef<'a>, MemoryOpFailure>

Perform a memory read.

fn write_access<'a>( &'a mut self, _ctx: &Context, addr: &Address, ) -> Result<Option<MemoryWriteRef<'a>>, MemoryOpFailure>

Perform a memory write. Return a mutable reference to the memory word being accessed or, if this is an attempt to write to a read-only location, return None.

fn reset_rtc(&mut self, ctx: &Context)

fn update_rtc(&mut self, ctx: &Context)

Trait Implementations

impl Debug for VMemory

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

Formats the value using the given formatter.