Protected Programmable Memory Cartridge and Computer System Using Same

A computer system for high-performance video and audio manipulations comprising a locked memory cartridge (14) and an audio/video/compact disk (CD) drive controller/coprocessor (32). The computer system has a central processing unit (30) (CPU) with at least one bus associated therewith, with the bus having at least one bus line. The cartridge comprises a readable memory (50), a memory control circuit (54), a lock control circuit (56), and a connector (376) all in circuit communication with each other. The connector allows the memory, the memory control circuit, and the lock control circuit to be pluggably connected in circuit communication with the CPU. The memory control circuit scrambles some of the bus lines, thereby scrambling the data in the memory on reset, and unscrambles the bus lines responsive to inputs from the lock control circuit. The lock control circuit monitors the bus, waiting for a proper combination of bus values to be asserted onto the bus, at which time the lock control circuit causes the memory control circuit to unscramble the bus lines. The audio/video/CD drive controller/coprocessor comprises a CPU interface, a CPU cache, a memory controller, a memory bus arbitrator, a DRAM refresher, a video controller, a CD drive controller, a digital signal processor (DSP) sound coprocessor, and a "blitter" graphics coprocessor in an integrated package.