Program correcting method and system

A program correction system, comprising:

• a main storage which stores a first program, a second program, and a third program, said main storage including an area which receives program correction information, a first area including a plurality of subareas, and a second area including a corresponding plurality of subareas;
• a command unit which commands correction of the second program;
• an external storage which stores the program correction information;
• a plurality of command processors, any particular one of which operates said first program and the remainder of which can simultaneously call said second program, each of said command processors corresponding to a respective one of the subareas of each of said first and second areas,
• wherein access to said main storage is shared by said command processors;
• wherein said first program is started up by said particular command processor in accordance with a program correction command from said command unit, said first program sets flags in the subareas of said first area except for the subarea corresponding to the particular command processor, and determines whether all of the flags have been cleared, and if so, executes, by said first program, correction of said second program in accordance with the program correction information;
• and
• wherein said third program is called by said second program and identifies a command processor which has called said third program, said third program determines whether a flag has been set in a subarea of said first area corresponding to the command processor which called said third program, and if so, clears the flag set in the corresponding subarea of said first area, said third program further determines whether a flag has been set in a subarea of said second area corresponding to the command processor which called said third program and iterates the determination until the flag is set before returning to said second program.

A method of correcting a program stored in a main storage access to which is shared by a plurality of command processors, wherein said command processors can call said program from said main storage simultaneously, and said main storage includes a first area having subareas corresponding to said command processors, said method comprising the steps of:

• fetching, by a first program, program correction information including at least a correction place and content of a second program;
• designating, by said first program, a command processor which executes a program correction from among said command processors and setting flags in all of said subareas in said first area corresponding to command processors other than the designated command processor in accordance with a command from the designated command processor;
• calling a third program by said second program, said third program being run by one of said plurality of command processors other than the designated command processor;
• determining, by said third program, whether flags have been cleared in the subareas of said first area corresponding to the command processors other than the designated command processor;
• and
• correcting said second program in accordance with the correction information in said first program when the flags in all of the subareas in said first area other than the subarea corresponding to the designated command processor have been cleared.