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Tyler



Joined: 19 Nov 2009
Posts: 1216
Location: NC, USA
Tyler
I was looking through HelpPC, under "Assembler Programming Topics" -> "8086 architecture" -> "Special Registers (386+ only)", in the list of special registers, they list CR0-CR3, and then TR4-TR7. Are TRx registers just mnemonics for CRx?
Post 11 Jul 2010, 01:05
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
Intel Vol. 3A wrote:
18.14 OBSOLETE INSTRUCTIONS
The MOV to and from test registers instructions were removed from the Pentium processor and future IA-32 processors. Execution of these instructions generates an invalid-opcode exception (#UD).
Post 11 Jul 2010, 01:19
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Tyler



Joined: 19 Nov 2009
Posts: 1216
Location: NC, USA
Tyler
What were they used for? Google returns nil.
Post 11 Jul 2010, 01:52
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
Seems that TR6 and TR7 where designed to test the TLB: http://www.logix.cz/michal/doc/i386/chp10-06.htm

The Wikipedia says that TR4-7 were introduced in the 80486. Although false, it may be true that this processor introduced TR4 for something (haven't googled anything about it).
Post 11 Jul 2010, 02:25
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sinsi



Joined: 10 Aug 2007
Posts: 713
Location: Adelaide
sinsi
Something to do with prefetch or cache in the 386/486 I think.

edit: http://www.rcollins.org/secrets/TR4Bug.html
Post 11 Jul 2010, 02:27
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17714
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revolution
IIRC, the functionality of the TRx registers was replaced by the more flexible MSR mechanism.
Post 11 Jul 2010, 06:35
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