Difference between revisions of "HLT"

From Intellivision Wiki
Jump to: navigation, search
m
Line 10: Line 10:
 
<tr><td>Addressing Mode</td><td>[[Implied Mode|Implied]]</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 asserts its HALT output, and performs no further processing once it executes this instruction.  The CPU ignores interrupts as well until the CPU gets reset.  HLT is mainly useful for debugging.<br/><br/>
+
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/>
 
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.
 
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.

Revision as of 18:28, 24 January 2005

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.