Abstract:
A COMPUTER MEMORY SYSTEM IN WHICH THE DATA IS TRANSFERRED BETWEEN HIGH-SPEED LOCAL STORAGE AND ONE OR MORE LEVELS OF A LARGER LOW SPEED STORAGE WHEREIN ALTERED DATA IS REWRITTEN IN HIGH-SPEED STORAGE IMMEDIATELY AND IN THE LOWSPEED STORAGE ON A CYCLE STEALING BASIS. CONTROLS ARE PROVIDED SO THAT WHEN A SMALL SEGMENT OF DATA IN A PARTICULAR BLOCK OR PAGE IN HIGH-SPEED STORE IS ALTERED AND INDICATOR IS SET. WHEN MEMORY BUSS TIME IS AVAILABLE TO THE LOW SPEED OR BACKUP STORE THESE INDICATORS WILL BE CHECKED AND WORDS OR LINES REWRITTEN IN SAID BACKUP STORE AS LONG AS A HIGHER PRIORITY JOB IS NOT ENCOUNTERED. WHEN IT IS DESIRED TO REPLACE A COMPLETE PAGE IN HIGH-SPEED STORAGE, INDICATORS FOR THAT PAGE ARE CHECKED AND ALL ALTERED WORDS ARE REWRITTEN IMMEDIATEDLY IN THE BACKUP STORE ON A HIGH PRIORITY BASIS AFTER WHICH THE PAGE IN THE HIGH-SPEED STORE MAY BE OVERWRITTER WITH NEW DATA FROM THE BACKUP STORE.
Abstract:
A light pen arrangement is described wherein the light pen has three degrees of freedom, viz. two-dimensional translation in the (X,Y) plane of a cathode ray tube screen and rotation about the projection of its own longitudinal axis to the normal of the screen. To sense the angular position of the light pen, at least two independent light sensitive elements, i.e., fiber optic bundles are required, the latter being suitably provided by dividing the bundle of fiber optics emerging from a single light pen into at least two separate groups and having photosensitive transducer respectively associated with each of the separate groups. When the light pen is placed on the screen and its presence there is sensed, an (X,Y) value pair is stored for the location of each light sensitive area of the light pen, i.e., each of the aforementioned separate fiber optic groups. The storing is accomplished by having an electron beam draw lines or points in each light sensitive area and, receiving in response thereto, interrupts for points or lines in the field of view of each fiber optic group, the (X,Y) coordinate of each point or line causing an interrupt and the fiber optic group that picked up the interrupt is now known to the computer or other control arrangement controlling the cathode ray tube. The computer or control arrangement can then compute the (X,Y) location of the light pen as the centroid of the individual areas and the angular position of the pen.