VGA Hardware: Difference between revisions
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clarification to the memory access non-sense that is VGA |
Chain 4 Bit entry is confusing to say the least |
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==== Chain 4 Bit ==== |
==== Chain 4 Bit ==== |
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'' This section needs a rewrite. Chain4 mode is perfectly normal function of VGA that standard BIOS 0x13 mode relies on for it's "linear" addressing. Basicly, when chain4 is set, lowest 2 bits of memory access address select the plane, and the address is shifted 2 bits down. The memory organization (as far as display goes) is always planar (like Mode-X) but the special mapping that is chain4 mode makes it appear linear. As such, I find it highly unlikely that the data about chain4 support below is correct. [[User:Mystran|Mystran]] 09:25, 9 December 2007 (CST) |
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'' Been testing the effect of Chain 4 on memory writes and output, and the results aren't consistent with one another. Chain 4 is located in the Sequencer which would mean setting/clearing it would have effect on video output. Furthermore i have been testing whether plane enable has effect in chain 4 writes. '' |
'' Been testing the effect of Chain 4 on memory writes and output, and the results aren't consistent with one another. Chain 4 is located in the Sequencer which would mean setting/clearing it would have effect on video output. Furthermore i have been testing whether plane enable has effect in chain 4 writes. '' |
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