TMPR3901F

2.1.2Address mapping

Address mapping in the TMPR3901F is performed by the direct segment mapping MMU in the R3900 Processor Core. The TMPR3901F uses the kseg2 reserved area (0xFF00 0000 - 0xFFFF FFFF) as follows.

0xFF00 0000 - 0xFF00 FFFF

address protection unit

0xFF20 0000 - 0xFF3F FFFF

debug support unit

The TMPR3901F outputs bus operation signals even when it accesses the above area. The TMPR3901F ignores bus operation input signals (ACK*, BUSERR*, etc) at that time.

2.2 Clock Generator

A quadruple-frequency PLL (phase locked loop) clock is built in and operates with an external crystal generator. It can be connected to the TMPR3901F internal PLL clock generator and quarter-frequency crystal oscillator.

The PLL and internal clock can be stopped with an external signal. The TMPR3901F supports a Reduced Frequency mode to control the clock frequency of the processor core by setting the Config register RF field (see Chapter 5 for details).

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Toshiba TX39 user manual Clock Generator, Address mapping