Difference between revisions of "HLT"

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m (Protected "HLT" ([edit=autoconfirmed] (indefinite) [move=autoconfirmed] (indefinite)))
 
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<tr><td>Interruptible</td><td>No</td></tr>
 
<tr><td>Interruptible</td><td>No</td></tr>
 
<tr><td>Opcode Range</td><td>$0000</td></tr>
 
<tr><td>Opcode Range</td><td>$0000</td></tr>
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<tr><td>Input Flags</td><td>None</td></tr>
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<tr><td>Output Flags</td><td>None</td></tr>
 +
<tr><td>Addressing Mode</td><td>[[Implied Mode|Implied]]</td></tr>
 
</table><br/>
 
</table><br/>
The Halt (HLT) instruction halts the [[CP1610]].  The CPU performs no further processing after receiving this instruction.  This also means that all further masked interrupts are ignored as well until the CPU gets reset.<br/><br/>
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The Halt (HLT) instruction halts the [[CP1610]].  The CPU asserts its HALT output, and performs no further processing once it executes this instruction.  The CPU ignores interrupts as well until the CPU is reset, or unhalted by a negative pulse on STPST.  HLT is mainly useful for debugging.<br/><br/>
Currently, it is unknown whether an unmasked interrupt arriving on the INTR input, or if a pulse on the STPST input will restart a halted CPU.  The existing CP1610 documentation does not say.  On the Intellivision, this is irrelevant as both inputs are tied to fixed valuesHLT is mainly useful for debugging.
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A pulse on the STPST input will restart a halted CPU.  On the Intellivision, this is mostly irrelevant as STPST tied to a fixed valueThe CPU is socketed, however, so one could modify their Intellivision in order to make this useful, say with a "debugging support" daughtercard.

Latest revision as of 08:27, 4 December 2010

Instruction NameHalt
MnemonicHLT
CP1610 Clock CyclesInfinity
InterruptibleNo
Opcode Range$0000
Input FlagsNone
Output FlagsNone
Addressing ModeImplied

The Halt (HLT) instruction halts the CP1610. The CPU asserts its HALT output, and performs no further processing once it executes this instruction. The CPU ignores interrupts as well until the CPU is reset, or unhalted by a negative pulse on STPST. HLT is mainly useful for debugging.

A pulse on the STPST input will restart a halted CPU. On the Intellivision, this is mostly irrelevant as STPST tied to a fixed value. The CPU is socketed, however, so one could modify their Intellivision in order to make this useful, say with a "debugging support" daughtercard.