Message board for the users of flat assembler.
> OS Construction > Am I forced to use 8086's instructions in real mode?
I would want know if I am forced to use only the 8086's instructions in real mode, because I am trying to write a little kernel (real mode) that checks if the CPU has the SSE4 set, using CPUID (that is not in the 8086 set) instruction.
|26 Aug 2011, 16:10||
I would want know if I am forced to use only the 8086's instructions in real mode
Today 8086 cpu is rare, anyway you can write code that checks the processor type..
* FROM INTEL *
Check for 8086:
Bits 12-15 of the FLAGS register are always set on the 8086 processor
Check for 286:
Bits 12-15 of the FLAGS register are always clear on the
286 processor in real-address mode.
Check for 386 processor:
The AC bit, bit #18, is a new bit introduced in the EFLAGS
register on the Intel486 processor to generate alignment faults.
This bit cannot be set on the Intel386 processor.
Check for 486 processor:
Checking for ability to set/clear ID flag (Bit 21) in EFLAGS
which indicates the presence of a processor with the CPUID instruction.
Nil Volentibus Arduum
|26 Aug 2011, 17:16||
Ok, thanks for these informations DJ Mauretto
|26 Aug 2011, 17:23||
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