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Notes
1. A Select instruction keeps the channel busy for 50ms. after actual termination of the instruction.
2. This sensible bit is set by a Select instruction and reset by a Read or Write instruction.
When a Read or Write instruction is accepted by the channel, block select becomes permissible. If the read or
write is terminated with a card on the capstan, block select remains permissible. If the card is not on the capstan
when read or write is terminated, then block select is not permissible.
When the channel accepts a block preselect, block select is not permissible until a Read or Write and the Block
Preselect instructions are executed. Any further block selects to the same unit during this period of time results
in an illegal operation. A Block Preselect should not be attempted unless a card is on the capstan. A card
leaving the capstan for any reason causes a
block select not permissible condition.
3. If 2
4
= 0, the specified block is within 8-10ms. from heads (Select complete). When this sensible bit is set
to zero (0) it will remain set until a read or write is executed.
4. Test for inoperability includes device inoperable, address verification error, or card absent error. Both address
verification error and card address error will cause device inoperability and set the inoperable bit.
When the address verification error occurs on a card that has been extracted, the device becomes inoperable
immediately, and the card is returned to its magazine after one revolution on the capstan. When the address
verification occurs on a card that is being preselected, the device will become inoperable at the time the preselect
card extract would be attempted. The card will not be extracted.
When a card absent error occurs, normal operation of the unit is allowed until the transport is cleared. Once
all the cards are in their magazines the hardware makes a second attempt to select the card. If the
card absent
indication is received after this attempt, the unit becomes inoperable and the sense bit (inoperable) is set.
5. If an attempt is made to select a card from a magazine position that does not contain a magazine, an illegal
operation sense indication is set. This indication is not received until 50ms. after the Select instruction is
terminated. At that time the 8-10ms. bit of the specific device is reset. This condition can be cleared by issuing
an
unconditional card removal command, which will reset the 8-10ms. bit. The illegal operation indication is
reset by any subsequent instruction to the device, including the
unconditional card removal.
6. This bit is reset (2° = 0) at the same time the option 0-2
4
bit (Test for specified block not within 8-10ms. from
heads) is reset; however, it is set to one (1) after a delay of 6-8ms. This bit is reset each time the specified
block is within 8-10ms. and then set to one (1) after 6-8ms. The state of this bit is not predictable after the
read or write is executed.
Outline of Operation
For each 3488 unit, there is an indicator associated with each of the sense bits (A address, options 0, 1, and 2).
Each indicator is set by the existence of the condition that results in a "yes" answer. The indicator is in a reset state if
the condition is not present. The test or tests called for by one (1) bits in the A address are performed on the device
specified by N. If any one of the conditions is true, the contents of the B Register are transferred to the P Register
causing a jump to the address indicated by B. If none of the specified indicators are set (all specified indicators are
reset), the next instruction in sequence is executed. General reset will automatically affect the following indicators,
provided that all cards are at rest in their magazines. If General Reset is depressed before all cards are at rest, the unit
goes inoperable.
These indicators will be reset:
1. Card select not permissible.
2. Card released due to 32 unserviced revolutions.
3. Illegal operation.
These indicators will be set:
1. Block select not permissible.
2. Specified block
not within 8-10ms.
General Reset will not reset the date error indicator (Option 1-2°).
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