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Home > Archive > Server + > January 2001 > 1U = ?
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| Hello everyone,
I placed the questions I could remember on www.tmqbase.com. There are now 31 questions. It does not give a complete overview but more the questions that I found interesting to remember. There is one question I could not find any reference for: How much is 1U. I now rack mounted devices are measured in U's, but I do not now how much it is exactly. Who knows the answer? If you find incorrect answers or have additional information, please let me know!
Boweise | |
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| You know, I guessed two inches.
But afterward I was curious too. I measured the spaces between holes on some rack equipment and I got something like 1 7/8 inches.
Lawrence | |
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| I found out the answer to my own question. In a Transtec cataloque I found the answer:
1U, or better, 1HU is one Height Unit. It represents 1.75" or 4.445 centimeters. A typical 1U device is a rack mounted hub or switch in a 19" patch rack.
Up to the next puzzling question: Which DMA channel is typically used for Plug & Play devices? You can choose from 1, 3, 5 and 6.
Who can help? | |
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| Don't know if this helps but here goes:
DMAs 1 and 5. Have no predetermined assignment. Common choice for sound cards and SCSI host adapters.
DMA 3. Has no predetermined assignment. Common choice for sound cards, network interface or SCSI.
DMA 6. Has no predetermined assignment. Its available for various uses.
I wonder if DMA 6 is the answer you seek?
Reference:
Jim Aspinwall. IRQ, DMA and I/O Resolving and preventing system conflicts pages 100-101. ISBN 0-7645-7519-8
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Spydah MD, FCAP, A+, Network+.
"Who dares, wins!"-SAS | |
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| DMA Channels. What a question!
Of the four choices I would choose DMA 6. Here's why:
DMA 1 and 3 are 8-bit channels that manage up to 64K of data in a single DMA operation. DMA 5 and 6 are 16-bit channels that manage data up to 128K.
Now, DMA Channel 3 is reserved for the floppy drive controller (so it is not 3), and DMA channel 5 is used by the hard-disk controller in PS/2 systems. (I would disqualify 5 also). Now we have 1 and 6 left. I would eliminate channel 1 just because this is only an 8-bit channel and would not seem the logical choice for plug-n-play. This leaves me with the 16-bit DMA channel 6 as the last choice.
Hope this helps!
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CCNA, MCSE, MCP+I, MCP, I-Net+, Network+, A+, MCP 2000 | |
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| Thanks for helping me out with this one, I have a few more which I will post a little later.
Boweise | |
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