Memory Type Range Registers

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Memory Type Range Registers

(architecture, video)
(MTRR) Registers in the Pentium Pro and Pentium II processors that can be used to specify a strategy for communication with the external memory and caches for a number of physical address ranges.

Strategies include write-through, write-back, or uncached(?). Such control is useful where the memory is located on a device and is accessed via some kind of device bus, e.g. a PCI or AGP graphics card, where caching would be of no benefit.
References in periodicals archive ?
Various penA mutations together with mtrR, porB and ponA mutations in Neisseria gonorrhoeae isolates with reduced susceptibility to cefixime or ceftriaxone.
In this study, the polymorphisms of the MTHFR genes (MTHFR C677T and MTHFR A1298C), MTR (MTR A2756G), and MTRR (MTRR A66G) were determined in malaria patients in Burkina Faso.
Polymorphisms in genes encoding the folate metabolizing enzymes MTHFR and MTRR might be linked to the etiology of cancer disorders.
In recent years, many studies reported that two genetic polymorphisms of the two genes, MTHFR 677C>T and MTRR 66A>G, could cause elevated blood homocysteine (Hcy) level in human [2-6].
MTHFR and MTRR genotype and haplotype analysis and colorectal cancer susceptibility in a case-control study from the Czech Republic.
Folic acid supplementation MTHFR and MTRR polymorphisms and the risk of childhood leukemia: the ESCALE study (SFCE).
For the study, the scientists used mice in which a gene called Mtrr was specifically mutated.
Less common causes are MTHFR deficiency, defects of methionine synthase [involving mutations in 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR, also known as CblG)], and defects in vitamin [B.sub.12] metabolism, such as mutations in methionine synthase reductase [5-methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR, also known as CblE)] and the CblD-variant-1 defect of the methylmalonic aciduria (cobalamin deficiency) cblD type, with homocystinuria (MMADHC) gene.
To function properly, MTR must be maintained in an active form; this is achieved by another enzyme called MTR reductase (MTRR), for which polymorphisms also exist.
Other critical gene expression (Bhmt, Cse, Chka, Tyms, Chdh, Gnmt, Mthfs, Mtr, Cept1, Mtrr, Etnk1, and Bad) involved in Hcy and phospholipids metabolism was also regulated by the different oils (Table 4).
placebo was significantly greater in patients with the 5-methyltetrahydrofolate me thyltrans-ferase (MTR) 2756 AG /GG or the MTR reductase (MTRR) 66 AG / GG genotype, the investigators said, noting that a trend toward significance was seen for the MTHFR 677CT/TT genotype.