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Table 1-4. Computer I/O Channel Numbers |
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|  MIL-D-81347C(AS)
TABLE 1-3. PRIORITY OF EVENTS (Continued)
TABLE 1-4. COMPUTER I/O CHANNEL NUMBERS
The Output or External Function Request maybe dropped to the
"0''state any time after detecting the Output Acknowledge or the External Function. The Output or
External Function Request cannot be reset immediately to indicate readiness of the peripheral equip-
ment to accept a second word because the computer will not recognize the second Output or External
Function Request unless. a minimum time delay of 0.8 microsecond is allowed between the completion
of the dropping of the first Output or External Function Request and the start of the setting of the sec-
ond Output or External Function Request. The timing would allow any peripheral equipment that
wishes to receive data from the computer at a maximum rate, to legitimately set the Output or Exter-
nal Function Request to the "1" state for the second time before the first Output Acknowledge or Ex-
ternal Function has dropped to the "0" state. This will not affect operation of the output cycle.
External Functions with Force - External Functions with Force
2.2.2.2
are unique in that no Request is sent by the peripheral equipment. The computer places the External
Function code on the 30 output data lines, and a minimum of 0.4 microsecond later energizes the
External Function Line. The External Function Line will remain in the stable "1" state for an inter-
val which may be as short as 2.05 (0.15) microseconds. (See Figure 1-6.)
The External Function word will remain on the data line for a
minimum of 0.5 microsecond after the External Function signal begins to drop.
The peripheral equipment has no control over the rate at which
External Functions with Force are sent. The External Function Line will drop to the "O" state for an
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