Status Codes - Control Data 3234 Series Hardware Reference Manual

STATUS CODES
The computer determines the state of the controller and storage units by the use of a
12-bit status response available to the data channel. The computer initiates a copy
status instruction and samples the status response on the lines from the controller.
The computer may sample a status response anytime it is connected, or after a con-
nect attempt is rejected if the controller and/or peripheral units are under control or
reservation by a different data channel. The status response may be a combination of
any of the available response bits.
The status response bits (Table 2-1) indicate the state of the controller and storage unit
to which the data channel is connected or last attempted to connect. A 1 in the bit
position indicates the condition is present (or has occurred); a 0 indicates the condition
is not present (or has not occurred). An interrupt must previously have been selected
or the associated interrupt status bit will be a 0 even though a condition that would
normally set the interrupt has occurred (that is, a copy status does not indicate that an
abnormal end of operation has occurred unless the abnormal end of operation interrupt
is selected). If the abnormal end of operation interrupt is selected, the operation ends,
the interrupt error status bits are set, and the interrupt is sent to the data channel
immediately upon occurrence of the error condition. However, if the abnormal end of
operation interrupt is not selected, the error status bits are set immediately upon
occurrence of the error condition even though the operation may not end until the buffer
is completed.
READY (XX xl) - BIT 0
The presence of bit 0 indicates that the unit last connected is in an operable condition
and ready for use. A storage unit is considered ready when it is available and ready
to operate. The unit becomes not ready for the following conditions.
DISK FILE AND DISK DRIVE UNI TS
1. Disk pack not loaded (applicable to disk drive unit only)
2. R/W heads not landed
3. Disk motor not up to speed
4. File or disk drive unsafe condition from selected unit (refer to Unsafe
Conditions)
5. No such unit
6. Wrong unit type designation
2-18 60333300 B