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Peter Flass (talk | contribs) →Channel programs: more description plus reference |
Peter Flass (talk | contribs) →Channel programs: commands |
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The count field (48-63) indicate the number of bytes to be transferred by this command.
All eight bits of commands that initiate I/O operations are passed to the device. "The modifier bits specify to the device how the command is to be executed." For example, for the [[IBM 2305]] DASD the ''write'' command ('MMMMMM01'BX) may have the following values:<ref>{{cite book |last1=IBM Corporation |title=Reference Manual for IBM 2835 Storage Control and IBM 2305 Fixed Head Storage Module |date=August 1971 |page=17 |url=http://bitsavers.org/pdf/ibm/dasd/2305/GA26-1589-2_2835_Storage_Control_and_2305_Fixed_Head_Storage_Module_Aug71.pdf |accessdate=Dec 5, 2019}}</ref>
{| class="wikitable"
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! Bit value !! Hexadecimal !! Description
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| 0001 1001 || '19'X || Write home address
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| 0001 0101 || '15'X || Write record 0
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| 0001 0001 || '11'X || Erase
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| 0001 1101 || '1D'X || Write count, key, and data
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| 0000 0001 || '01'X || Write special count, key, and data
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| 0000 0101 || '05'X || Write data
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| 0000 1101 || '0D'X || Write key and data
|}
==References==
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