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Power
Addre
ss
Write
Enable
Flash
Address
Bit
7
6
5
4
3
2
1
0
Name
VB2
VB I
-PFIRQ
-
-WEN
VPP
PS3
PS2
Read/
Write
R
R
R
R
R/W
R/W
R/W
R/W
Description:
Bits 7, 6
(VB1-2)
Battery monitor. 1 = dead or missing battery. B i t 6 = battery 1 (J4), Bit 7 =
battery 2 (J5).
Bits 5
(-PFIRQ)
Power fail interrupt status. Zero if system
(not battery)
power falls below
threshold.
Bit 4
Ampro reserved. Always set to 0.
Bit 3
(WEN)
Software controlled write protect for SRAMs or Flash EPROMs. 1 is write
protect, 0 is enabled,
Bit 2
(VPP)
12 volt Flash EPROM programming voltage. Enabled (=1) by software.
Bits 0-1
(PS2, PS3)
Page select. Used to select 64K byte pages from larger memory devices. P S I
and PS2 are in Control Register 1. (See Table 3-2.)
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XVME-956 Manual
August 1994
5.8.2 C o n t r o l Register 2 Functions
The content of Control Register 2 provides additional device page selection information, + 1 2 volt Flash
EPROM programming voltage control, SRAM write protect, power fail alarm monitoring, and battery
voltage monitoring. Table 5-20 indicates the use of the various register bits.
Table 5-20. Control Register 2 Bit Usage
5-21