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The boot ROM consists of 1 MB of on-board flash EPROM. The boot ROM includes the hardware-specific code and tables needed to start up the computer, to load an operating system, and to provide common hardware access services.
To minimize the number of pins on Uni-N, the boot ROM is connected to the 66 MHz PCI bus. The boot ROM uses the thirty two PCI AD lines and four PCI byte enable lines for address and data. Uni-N has separate pins for Chip Enable, Output Enable, and Write Enable signals to keep the ROM from interfering with proper PCI bus operation.