http://channelf.se/veswiki/index.php?title=Status_register&feed=atom&action=historyStatus register - Revision history2024-03-29T01:48:38ZRevision history for this page on the wikiMediaWiki 1.28.0http://channelf.se/veswiki/index.php?title=Status_register&diff=139&oldid=prevE5frog: 1 revision2012-11-16T21:23:46Z<p>1 revision</p>
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</td></tr></table>E5froghttp://channelf.se/veswiki/index.php?title=Status_register&diff=138&oldid=prevAdmin at 21:27, 20 November 20042004-11-20T21:27:06Z<p></p>
<p><b>New page</b></p><div>The status register is an 8-bit [[register]] used by the F8 to store the results of a previous operation, or as a flag to allow [[interrupts]]. Only the lower 5 bits of the register are used. In the '''LR''' [[opcode]], the status register can be accessed using the letter '''W''', though it can only be transferred back and forth from the register '''J''', or scratchpad register 9.<br />
<br />
The status register is primarily affected by mathematical opcodes, such as addition or any [[binary logic]]. When [[branch|branching]], the opcodes apply a [[bitmask]] to the status register and determine whether the condition is true or not.<br />
<br />
== Status Register Bits ==<br />
<br />
This table breaks down the status register bit-by-bit ([[least significant bit|LSB]] is bit 0):<br />
<br />
<table border="1" style="width: 50%" cellspacing="1" cellpadding="4"><br />
<br />
<tr><br />
<th>Bit</th><br />
<th>Name</th><br />
<th>Description</th><br />
<br />
</tr><br />
<br />
<tr><br />
<td>0</td><br />
<td>Sign</td><br />
<br />
<td>Carries the sign of the last operation (positive, negative)</td><br />
</tr><br />
<br />
<tr><br />
<td>1</td><br />
<br />
<td>Carry</td><br />
<td>Set if the last operation resulted in a [[carry]].</td><br />
</tr><br />
<br />
<tr><br />
<br />
<td>2</td><br />
<td>Zero</td><br />
<td>Set if the value of the last operation was 0.</td><br />
</tr><br />
<br />
<tr><br />
<td>3</td><br />
<td>Overflow</td><br />
<td>Set if the last operation resulted in too large a number</td><br />
<br />
</tr><br />
<br />
<tr><br />
<td>4</td><br />
<td>ICB</td><br />
<br />
<td>Set if interrupts are to be enabled (use '''EI''', '''DI''')</td><br />
</tr><br />
<br />
<tr><br />
<td>5</td><br />
<br />
<td>''(unused)''</td><br />
<td>&nbsp;</td><br />
</tr><br />
<br />
<tr><br />
<br />
<td>6</td><br />
<td>''(unused)''</td><br />
<td>&nbsp;</td><br />
</tr><br />
<br />
<tr><br />
<td>7</td><br />
<td>''(unused)''</td><br />
<td>&nbsp;</td><br />
<br />
</tr><br />
</table></div>Admin