General-Purpose Software-Readable Header (Srh) Switch (S3); Nvram/Rtc & Watchdog Timer Registers; Figure 1-4. General-Purpose Software-Readable Header - Motorola MVME2400 Series Programmer's Reference Manual

Board Description and Memory Maps
1
General-Purpose Software-Readable Header (SRH) Switch
(S3)
Switch S3 is an eight pole single-throw switch with software readable
switch settings. These settings can be read as a register at ISA I/O address
$801 (hexadecimal). Each switch pole can be set to either logic 0 or logic
1. A logic 0 means the switch is in the ON position for that particular bit.
A logic 1 means the switch is in the OFF position for that particular bit.
SRH Register Bit 0 is associated with Pin 1 and Pin 16 of the SRH and
SRH Register Bit 7 is associated with Pin 8 and Pin 9 of the SRH. The SRH
is a read-only register.
If Motorola's PowerPC firmware, PPCBug, is being used, it reserves all
bits, SRH0 to SRH7. If it is not being used, the switch can be used for other
applications.
1

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

NVRAM/RTC & Watchdog Timer Registers
The M48T59/559 provides the MVME2400 series 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,
1-26
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16
ON
SRH0 = 0
SRH1 = 0
SRH2 = 0
SRH3 = 0
SRH4 = 0
SRH5 = 0
SRH6 = 0
SRH7 = 0
16
1
ON
SRH0 = 1
SRH1 = 1
SRH2 = 1
SRH3 = 1
SRH4 = 1
SRH5 = 1
SRH6 = 1
SRH7 = 1
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