IBM 610 Manual Of Operation

Also see for 610: Technical overview and introduction

50 IBM 6 10The decimal point will appear as a bright spotbelow the digit column immediately following thepoint. During entry an additional spot (called thetag) will appear at the lower edge of the tube facebelow the digit column that is ready to receive adigit. Occasionally, the operator will see a spot nearthe top edge of the tube; this spot is used for internalcontrol purposes and need not concern the operator.Figure 54 shows a partially entered number as itwould appear on the cathode ray tube display. Thenumber so far entered in the figure is 022.37. A brightspot below the digit 3 in the fifth position from theleft indicates that the decimal point immediately pre-cedes the 3 . A bright spot near the bottom of the dis-play in the seventh position from the left indicatesthat that position of the register is ready to receive adigit. The sign of the number will be entered intothe machine after all of the digits up to fifteen havebeen entered and will appear at the far left of the dis-play.Negative numbers are displayed in tens comple-ment form; e.g., -0.892 is displayed assign9999999999999999.1080000000000000When the machine is operating in the auto-pointmode, the number entered is automatically positionedas seen on the cathode ray tube so that all digits tothe left of the decimal point will appear in the lefthalf of the tube and all of the digits to the right ofthe point will appear in the right half of the tube.Thus, the point will lie below the first column ofthe right-hand array.The cathode ray tube is an indication of the exist-ence of data in the selected register and is not recom-mended for the reading of the data in the selectedregister. If a person wishes to examine in detail thecontents of the selected register, he need only readout to the typewriter.