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Board Description and Memory Maps

General-Purpose Readable Jumpers

Headers J10 (on the MVME2300SC) and J17 (on the MVME2300) provide eight software-readable jumpers. These jumpers can be read as a register at ISA I/O address $801 (hexadecimal). Bit 0 is associated with header pins 1-2; bit 7 is associated with pins 15-16. The bit values are read as a 0 when a jumper is installed, and as a 1 when the jumper is removed. The PowerPC firmware, PPCBug, reserves all bits, SRH0 to SRH7. The board is shipped from the factory with J10 / J17 set to all 0s (jumpers on all pins), as shown in Figure 1-4.

J10/J17 PPCBug INSTALLED

Bit 0 (SRH0) 1

Bit 1 (SRH1)

Bit 2 (SRH2)

Bit 3 (SRH3)

Bit 4 (SRH4)

Bit 5 (SRH5)

Bit 6 (SRH6)

Bit 7 (SRH7) 15

2Reserved for future use

Reserved for future use

Reserved for future use

Reserved for future use

Reserved for future use

Reserved for future use

Reserved for future use

16 Reserved for future use

Figure 1-4. General-Purpose Software-Readable Header

NVRAM/RTC and Watchdog Timer Registers

The M48T59/559 provides the MVME2300 series boards with 8K of non- volatile SRAM, a time-of-day clock, and a watchdog timer. Accesses to the M48T59/559 are accomplished via three registers:

The NVRAM/RTC Address Strobe 0 register

The NVRAM/RTC Address Strobe 1 register

The NVRAM/RTC Data Port register

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Motorola MVME2300 Series manual General-Purpose Readable Jumpers, NVRAM/RTC and Watchdog Timer Registers