Cray CRAY-1 - Page 208

The dead start sequence is initiated from the maintenance control unit
(MCU). The sequence is described in detail in Section 3. During the
dead start sequence, the MCU loads a program containing an exchange
package at absolute address zero in the CRAY-l memory. A signal from
the MCU causes the CRAY-l to begin execution of the program pointed to by
the exchange package.
FLOATING POINT RANGE ERRORS
Detection of the floating point range error initiates an interrupt if the
floating point mode flag is set in the mode register and monitor mode is
not in effect. The programmer has the capability via the 0022 instruction
to clear the floating point mode flag so that results going out of range
are prevented from interrupting. This is especially useful for operations
such as the vector merge instruction usage in subroutines such as SINE and
COSINE, where some results may be known to go out of range. At the end
of the code sequence, the programmer normally resets the floating point
mode via a 0021 instruction.
2240004
C-2
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