MON - Revision history

TArntsen: Typo: 256->255

2010-08-07T13:31:08Z

Typo: 256->255

← Older revision		Revision as of 13:31, 7 August 2010
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	==== Number of Monitor Calls ====		==== Number of Monitor Calls ====
	The 8 bit wide <number> limits the possible ND-100 monitor calls to the range 0 to maximum ~~256~~, or 377<sub><small>8</small></sub>		The 8 bit wide <number> limits the possible ND-100 monitor calls to the range 0 to maximum 255, or 377<sub><small>8</small></sub>

	The various monitor calls are documented in {{ND-doc\|60.228.1}}.		The various monitor calls are documented in {{ND-doc\|60.228.1}}.

TArntsen: Adding/editing more details than maybe anyone wants

2010-08-07T13:18:37Z

Adding/editing more details than maybe anyone wants

← Older revision		Revision as of 13:18, 7 August 2010
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	Other monitor calls, for example those with no error state like 153 113<sub><small>8</small></sub> (''MON CLOCK''), have no skip return.		Other monitor calls, for example those with no error state like 153 113<sub><small>8</small></sub> (''MON CLOCK''), have no skip return.

	The instruction causes an internal interrupt to program level 14~~, with~~ the <number> ~~value from the lower 8 bits of the instruction loaded sign-extended into~~ the T register on level 14. The ~~sign-extension~~ is ~~a method for~~ the ~~interrupt handler to detect that~~ the ~~T register was set, which identifies the interrupt as caused by a MON~~ instruction~~<ref>SIN-L STD A listing part two, March 1989</ref>~~. The ~~lower 8 bits of~~ the T register ~~(the original <number>)~~ is ~~used to call the correct system function through a look~~-~~up table~~.		==== MON handling in SINTRAN-III ====
			The instruction causes an internal ''Monitor Call'' interrupt (bit 1 in the [[IIC register\|Internal Interrupt Code register]] <ref>{{ND-doc\|06.014.02}} page 2-17</ref> <ref>{{ND-doc\|06.015.02}} page 2-39</ref>) to program level 14. It differs from other internal interrupt sources in that the monitor call or <number> is found in the [[T register]] on level 14. The <number> value is the lower 8 bits of the instruction. The value in the T register is sign-extended.

			In SINTRAN-III version L at least, the interrupt number is not used for detecting that the interrupt was caused by a monitor call, instead the sign-extension of the T register is used a method to detect that the T register was set, which would only happen if the interrupt was caused by a MON instruction. The lower 8 bits of the T register (the original <number>) is used to call the correct system function through a look-up table.<ref>SIN-L STD A listing part two, March 1989</ref>

			==== Number of Monitor Calls ====
	The 8 bit wide <number> limits the possible ND-100 monitor calls to the range 0 to maximum 256, or 377<sub><small>8</small></sub>		The 8 bit wide <number> limits the possible ND-100 monitor calls to the range 0 to maximum 256, or 377<sub><small>8</small></sub>

TArntsen: MON instruction

2010-08-06T14:38:59Z

MON instruction

New page

{{InstructionBox
|Mnemonic=MON
|Description= Monitor Call
|Format=MON <number>
|Code=153 000
|Affected=Various
|Architecture=[[ND-100]], [[ND-110 CPU|ND-110]]
}}

'''MON''' is an assembly instruction.

The instruction is used for monitor calls. A "monitor call" is equivalent to a syscall in Unix. Depending on the specific monitor call, various registers may be loaded with call-specific values before the MON instruction is called, and return values may be retrieved from registers after the call. Parameters and data may also be stored and retrieved from memory addresses.

Some monitor calls will cause the [[P register|program counter]] to be incremented by two instead of one (a "skip return") if the monitor call succeded, and by one in case of error. For such monitor calls the instruction immediately following MON will typically be a jump instruction to an error handler, while the next one after that is the instruction to execute in case of success.

Other monitor calls, for example those with no error state like 153 1138 (''MON CLOCK''), have no skip return.

The instruction causes an internal interrupt to program level 14, with the <number> value from the lower 8 bits of the instruction loaded sign-extended into the T register on level 14. The sign-extension is a method for the interrupt handler to detect that the T register was set, which identifies the interrupt as caused by a MON instruction<ref>SIN-L STD A listing part two, March 1989</ref>. The lower 8 bits of the T register (the original <number>) is used to call the correct system function through a look-up table.

The 8 bit wide <number> limits the possible ND-100 monitor calls to the range 0 to maximum 256, or 3778

The various monitor calls are documented in {{ND-doc|60.228.1}}.

== References ==
<references/>
*{{ND-doc|06.014.02|Page 3-56}}
*{{ND-doc|06.029.01|Page 81}}
*{{ND-doc|60.228.1}}

[[Category:ND-100 instructions]]