Xycom XVME-956 Series Manual page 90

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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.
Bit
Name
Read/
Write
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Bits 7, 6
(VB1-2)
Bits 5
(-PFIRQ)
Bit 4
Bit 3
(WEN)
Bit 2
(VPP)
Bits 0-1
(PS2, PS3)
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Table 5-20. Control Register 2 Bit Usage
Power
7 6 5
VB2 VB I -PFIRQ
R R R
Description:
Battery monitor. 1 = dead or missing battery. B i t 6 = battery 1 (J4), Bit 7 =
battery 2 (J5).
Power fail interrupt status. Zero if system (not battery) power falls below
threshold.
Ampro reserved. Always set to 0.
Software controlled write protect for SRAMs or Flash EPROMs. 1 is write
protect, 0 is enabled,
12 volt Flash EPROM programming voltage. Enabled (=1) by software.
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.)
Addre Write Flash
ss Enable
4 3 2
- -WEN VPP
R R/W R/W
XVME-956 Manual
August 1994
Address
1 0
PS3 PS2
R/W R/W
5-21