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Reinitialisation requires operator action at the processor console. The operator must:
stop the processor by setting the “enable/halt” switch to “halt”;
set the switch register with the address of the hardware bootstrap loader program;
depress and release the “ load address” switch;
move the “enable/halt” switch to “enable”;
depress and release the “start” switch.
This activates the bootstrap program which is permanently recorded in a ROM in the processor.
The bootstrap loader program loads a larger loader program (from block #0 of the system disk), which looks for and loads a file called “/unix” into the low part of memory.
It then transfers control to the instruction loaded at address zero.
Address zero is occupied by a branch instruction (line 0508), which branches to location 000040, which contains a jump instruction (line 0522), which jumps to the instruction labelled “start” in the file “m40.s” (line 0612).
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