Handspring Visor Main Board -- Processor Side

The DragonBall MC68EZ328 PU16V is an integrated portable system controller manufactured by the Motorola Corporation. It has 32-bit internal address bus, and 24-bit external address bus capable of addressing maximum of 4 × 16 MB blocks of memory with chip selects CSA and CSB. In addition, chip selects CSC, and CSD can address 4 × 4 MB blocks of memory. It has glue-less interface capable of directly supporting SRAM, EPROM, and Flash memory.

A block diagram of the MC68EZ328 processor shows that it had only UART and infrared support for communication with the external world. Hence, for the USB communication, they had to connect an external IC to provide that facility.

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