Abstract: Apparatus and a method are disclosed to enable on-line modification and upgrading of terminal software in a communication network while maintaining the integrity of communication between a service provider and a subscriber using the network. Software is downloaded on a booter channel on the communication network. A subscriber terminal, coupled to the network initiates a communication with the network to receive downloaded booter data. The downloaded data is stored, and a checksum is computed from at least a portion of the downloaded data. The checksum is tested for validity, and control of the subscriber terminal is released to the downloaded software only if the checksum is valid.

Abstract: A method and apparatus prevent unauthorized programming viewing via a downloadable cable television converter. A booter checksum is computed from data contained in a downloaded booter image. A valid checksum is extracted from tag data associated with a scrambled program signal transmitted on the cable system. The booter checksum is compared to the extracted valid checksum. If the booter checksum and valid checksums match, a descrambler is enabled to descramble the scrambled program signal. If the checksums do not match, the descrambler is not enabled. In this manner, a pirate is prevented from downloading a false booter image to defeat the integrity of the converter.

Abstract: Apparatus restricts access to a communication network having at least one service node for providing services to subscribers. A subscriber terminal, coupled to the communication network, includes a secret node key. A succession of frame verifier (FV) codes, derived through the use of the secret node key, is generated and transmitted on the network. A network access controller (NAC), coupled to the network, includes a record of the secret node key and uses the key to encrypt a seed which is transmitted to the subscriber terminal for use in generating the FV codes. The NAC also independently computes the succession of FV codes which should be generated by the subscriber terminal. A distributed access controller (DAC), coupled to the communication network, includes a look-up table for storing the succession of FV codes computed by the NAC. The FV codes transmitted by the subscriber terminal are detected and compared to those stored in the look-up table.

Abstract: A technique for processing pictorial information to enable its display on a desired display device independent of the latter's resolution characteristics includes a unique encoding procedure and a corresponding decoding and display procedure. Attributes of each element of a picture or image (such as its color) are specified by a group of N bits. The bits are assembled to form M-bit active portions of a series of bytes. M and N need not be integrally related. Ones of the words also define the size of the elements with respect to a unit display space (the horizontal and vertical dimensions of each element can be different), the order in which the elements are arranged in the picture (e.g., left to right or vice versa) and the value of N.

Abstract: The present terminal independent color memory for a digital image display system provides for inter-system compatability, color display systems generally having varying modes of access to color memories, varying color memory capacities, and features such as blinking implemented in varying ways. The data processor (1) of the present system may access color memory (6a) of video controller (6) or color values stored in permanent memory (9) or random access memory (10), responsive to the same command language. The present data processor (1) is also capable of entering color data values comprising color hues and gray levels into color memory for use in a terminal independent manner. Multiple process chained blinking from a particular color to a particular color is also provided by the present processor, the several processes in time-delayed relationship to one another.

Abstract: A graphic display terminal is arranged to receive from a sending source drawing instructions containing the description of a display character. The terminal, under control independent from the sending source, interprets each received drawing instruction into a particular picture description bit pattern tailored to the characteristics of the terminal display device. The interpreted bits are then stored in a graphic repertory for subsequent retrievel under control of code received from the sending source. In this manner dynamically redefinable character sets may be created and used without regard to a particular terminal implementation.

Abstract: A method and apparatus for compactly describing an image made up of concatenated lines or filled polygons. The drawing of lines for the image begins at an initial drawing point determined in a coordinate system defined by a unit screen and proceeds from point to point with the relative coordinates of each successive point specified as a positive or negative step in the horizontal and/or the vertical direction from the previous point. The step size parameters which separately define both the amount of a change in the horizontal direction and the amount of a change in the vertical direction are initially specified in fractional parts of the unit screen and remain constant in magnitude throughout the operation. The image is reflected about the horizontal axis and about the vertical axis simply by changing the sign of the step sizes. Turning on and off the drawing process is also facilitated.