Mc Louth Steel - First Online Computer Control

First Online Computer Control

Online computer control of steel making processes became a reality with the first use of computers on a hot strip mill in 1962. McLouth Steel used a General Electric 312 computer for gauge control on the finishing train of a semi-continuous mill. The aim was to set up the initial roll gap and then establish correct gauge as soon as the head end of the strip emerged onto the runout table. The finishing train started running under continuous computer control on November 1, 1962.

"Probably the most exciting application of the GE 312 was to the hot strip mill of McLouth Steel Co. in Michigan. It was a difficult design inasmuch as each step in the process had to be varied on the basis of the measured values of the previous step. This required continuous high speed feedback to set the six different hot stands with absolute accuracy and reliability being essential; an error at one point could be magnified at the next, causing an entire process to go out of control. Fortunately, the GE 312 met the challenge." H. Oldfield, General Manager of the GE Computer Department.

The Solid State circuitry of a GE 312 computer was composed of 2500 diodes, 2500 transistors, and 12,000 resistors, but no magnetic core memory. There were 20 binary digits per word or per instruction. All arithmetic was fixed point. Numbers were 19 bits plus the associated positive or negative sign, not a very big number range when expressed in decimal form, just -524,287 to +524,287. The GE 312 was designed by A. Spielberg of the GE Computer Department that was newly formed in 1957.