IOT: Difference between revisions
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{{InstructionBox | {{InstructionBox | ||
|Mnemonic=IOT | |Mnemonic=IOT SKA | ||
|Description=Perform monitor call | |Description=Perform monitor call | ||
|Format=IOT SKA <number> | |Format=IOT SKA <number> | ||
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}} | }} | ||
'''IOT''' | '''IOT''' is a [[NORD-1]] I/O instruction which is the NORD-1 equivalent of the [[NORD-10]]/[[ND-100]] I/O instruction [[IOX]]. IOT is undocumented. The MAC Assembler manual <ref>*{{ND-doc|60.096}}</ref> states that ''the NORD-10 may also be delivered with a NORD-1 compatible I/O instruction IOT'' (page 2-27). | ||
A special case of IOT is the '''IOT SKA''' instruction, it is still used by very old applications like the [[NPL]] compiler. Old ND system applications tend to keep old code even when updated. | |||
The [[BRF EDITOR]] command ''LIST-BRF'' is aware of 161.xxx instructions and lists them as '''IOT SKA'''. The [[BRF Linker]] ''LIST-BRF-CODE'' command will only list the octal value, and no mnemonic. | The [[BRF EDITOR]] command ''LIST-BRF'' is aware of 161.xxx instructions and lists them as '''IOT SKA'''. The [[BRF Linker]] ''LIST-BRF-CODE'' command will only list the octal value, and no mnemonic. | ||
<tt>'IOT SKA', as used by the BRF EDITOR probably means 'IOT Systemkall' which translates to 'IOT System Call' from Norwegian.''</tt> | |||
As described above, the instruction pre-dates [[SINTRAN III|SINTRAN-III]] and the [[NORD-10]]/[[ND-100|N1xx]] CPUs, but applications using this instruction, within a certain range of <number> values, are still able to execute on the newer systems due to a trick explained below. This allows applications like [[NPL]] to work. | |||
==== Implementation details ==== | ==== Implementation details ==== | ||
The instruction does not exist in the NORD-10/ND-1x0 CPUs, but it will trigger a ''Privileged Instruction'' exception in SINTRAN-III (bit 6 in the [[IIC register|Internal Interrupt Code register]] <ref>{{ND-doc|06.014.02}} page 2-17</ref>). The snippet of SINTRAN-III code which handles the exception looks as follows: <ref>SIN-L STD A listing part two, March 1989</ref> | The instruction does not exist in the NORD-10/ND-1x0 CPUs (except when specially ordered with the NORD-10), but it will trigger a ''Privileged Instruction'' exception in SINTRAN-III (bit 6 in the [[IIC register|Internal Interrupt Code register]] <ref>{{ND-doc|06.014.02}} page 2-17</ref>). The snippet of SINTRAN-III code which handles the exception looks as follows: <ref>SIN-L STD A listing part two, March 1989</ref> | ||
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072404 IIC06: IF ACTLV=ALEVL THEN % PRIVILIGED INSTRUCTION | 072404 IIC06: IF ACTLV=ALEVL THEN % PRIVILIGED INSTRUCTION [[Wikipedia:Sic|[''sic'']]] | ||
072410 RTREF.ACTPRI/\74000 SHZ -4+"NMPIT+LV14B+ERNG2"% SET USERS NORMAL PIT AS ALT. PIT | 072410 RTREF.ACTPRI/\74000 SHZ -4+"NMPIT+LV14B+ERNG2"% SET USERS NORMAL PIT AS ALT. PIT | ||
072415 X:=PERR; *TRR PCR | 072415 X:=PERR; *TRR PCR | ||
072417 X.SN1=:D % D= THE ILL.INSTR. | 072417 X.SN1=:D % D= THE ILL.INSTR. | ||
072421 "NMPIT+ADPIT+LV14B+ERNG2"; *TRR PCR % RESET PCR | 072421 "NMPIT+ADPIT+LV14B+ERNG2"; *TRR PCR % RESET PCR | ||
072423 IF 177600/\D=161000 THEN T:=177/\D; GO FAR MONCALL FI % IF 161XXX THEN MONCALL | 072423 IF 177600/\D=161000 THEN T:=177/\D; GO FAR MONCALL FI % IF 161XXX THEN MONCALL | ||
072433 IBITNO; T:=PERR; CALL 9ERR(#24) % GIVE ERROR MESSAGE | 072433 IBITNO; T:=PERR; CALL 9ERR(#24) % GIVE ERROR MESSAGE | ||
072437 GO FAR ABOR % TERMINATE CURRENT RUNNING PROGRAM | 072437 GO FAR ABOR % TERMINATE CURRENT RUNNING PROGRAM | ||
072440 FI; GO FAR TDTLEV % MAY BE ILL.INSTRUCTION ON ILLEGAL LEVEL | 072440 FI; GO FAR TDTLEV % MAY BE ILL.INSTRUCTION ON ILLEGAL LEVEL | ||
{{DocPreEnd}} | |||
The NPL code "'''IF 177600/\D=161000 THEN T:=177/\D; GO FAR MONCALL FI'''" translates to the following pseudocode: | The NPL code "'''IF 177600/\D=161000 THEN T:=177/\D; GO FAR MONCALL FI'''" translates to the following pseudocode: | ||
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if instruction is in the 161000 (octal) range, and <number> is in the range 0x00-0x7f, then | if instruction is in the 161000 (octal) range, and <number> is in the range 0x00-0x7f, then | ||
handle as monitor call (<number>) | |||
else | else | ||
handle as any other illegal instruction, abort program | |||
endif | endif | ||
{{DocPreEnd}} | |||
The interrupt handler detects if the instruction is | The interrupt handler detects if the instruction is a 161000 instruction, and, if so, handles it as a [[MON]] instruction (153000<sub><small>8</small></sub>), i.e. a monitor call (within the allowed range for <number>), instead of aborting the program. The instruction is thus an old version of the [[MON]] instruction, and the old calls map one-to-one to the SINTRAN-III functions as long as they are below 128 decimal (i.e. up to and including 'MON 177'). | ||
== References == | == References == | ||
Latest revision as of 07:45, 26 May 2016
| IOT SKA | |
|---|---|
| Description | Perform monitor call |
| Format | IOT SKA <number> |
| Code | 161 0008 |
| Affected | Various registers, depending on <number> |
| Type | User |
| Architecture | NORD-1 |
IOT is a NORD-1 I/O instruction which is the NORD-1 equivalent of the NORD-10/ND-100 I/O instruction IOX. IOT is undocumented. The MAC Assembler manual [1] states that the NORD-10 may also be delivered with a NORD-1 compatible I/O instruction IOT (page 2-27).
A special case of IOT is the IOT SKA instruction, it is still used by very old applications like the NPL compiler. Old ND system applications tend to keep old code even when updated.
The BRF EDITOR command LIST-BRF is aware of 161.xxx instructions and lists them as IOT SKA. The BRF Linker LIST-BRF-CODE command will only list the octal value, and no mnemonic.
'IOT SKA', as used by the BRF EDITOR probably means 'IOT Systemkall' which translates to 'IOT System Call' from Norwegian.
As described above, the instruction pre-dates SINTRAN-III and the NORD-10/N1xx CPUs, but applications using this instruction, within a certain range of <number> values, are still able to execute on the newer systems due to a trick explained below. This allows applications like NPL to work.
Implementation details
The instruction does not exist in the NORD-10/ND-1x0 CPUs (except when specially ordered with the NORD-10), but it will trigger a Privileged Instruction exception in SINTRAN-III (bit 6 in the Internal Interrupt Code register [2]). The snippet of SINTRAN-III code which handles the exception looks as follows: [3]
The NPL code "IF 177600/\D=161000 THEN T:=177/\D; GO FAR MONCALL FI" translates to the following pseudocode:
The interrupt handler detects if the instruction is a 161000 instruction, and, if so, handles it as a MON instruction (1530008), i.e. a monitor call (within the allowed range for <number>), instead of aborting the program. The instruction is thus an old version of the MON instruction, and the old calls map one-to-one to the SINTRAN-III functions as long as they are below 128 decimal (i.e. up to and including 'MON 177').
References
- ↑ *Norsk Data Document ND–60.096 MAC INTERACTIVE ASSEMBLY AND DEBUGGING SYSTEM USER'S GUIDE
- ↑ Norsk Data Document ND–06.014.02 ND-100 REFERENCE MANUAL page 2-17
- ↑ SIN-L STD A listing part two, March 1989
- Norsk Data Document ND–60.228.1 SINTRAN III Monitor Calls manual