Abstract: A microprocessor, comprising a register 18 for setting either a first mode in which a trap instruction is not executed, or a second mode in which the trap instruction can be executed is set, wherein an instruction decoding circuit 23, in case of operating in the first mode, outputs an internal signal SG1 directing execution of a subroutine call, when decoding a subroutine call instruction, to an instruction executing unit 14, and in case of operating in the second mode, outputs the internal signal SG1 directing execution of a trap when decoding the subroutine call instruction, to the instruction executing unit 14. By such a configuration, a break can be effected in a unit of subroutine under a simple control when debugging the program, and by enabling the breaking without decoding a program to be debugged, the debugging can be effected efficiently under a real time environment.

Abstract: A method of preheating scrap metal with impure gases discharging from a metallurgical vessel includes the steps of conducting a first portion of the gases to a container of scrap metal, contacting the scrap metal with the gases for preheating the same whereby additional impurities are generated, withdrawing the impure gases after contact with the scrap metal and mixing the same with a second portion of impure gases from the metallurgical vessel, thermally cracking the mixture in a combustion chamber to remove impurities and thereafter removing particular matter from the gases prior to the discharge to the atmosphere.

Abstract: A method and apparatus for preheating scrap metal within pure gases discharged from a metallurgical vessel. The method comprises the steps of burning the gases in a combustion chamber to remove impurities therefrom, conducting a first portion of the combustion products to a container of scrap metal, contacting the scrap metal with the combustion products for preheating the scrap metal whereby additional impurities are generated, washing in a wet scrubber the mixture of combustion products and additional impurities, mixing the scrubbed combustion products and additional impurities with a second portion of the combustion products from the combustion chamber, and removing particulates from the mixture.