Boot Flash Write Enable Link (P3 3-4) And User Flash Write Enable Link (P3 5-6); Jtag Scanbridge Enable Link (P4 1-2); Table 2-6 Links P3 3-4 And 5-6; Table 2-7 Link P4 1-2 - GE IMP2B Hardware Reference Manual

2.7 Boot Flash Write Enable Link (P3 3-4) and
User Flash Write Enable Link (P3 5-6)
These links tell the software how it should configure the default non-persistent
sector protection of the Boot and User areas of Flash. This emulates the type of
protection previously implemented in hardware for users who are familiar with
previous revisions of, or are using, existing software on the IMP2B. The state of these
links is reflected in the EPLD
These links are provided for compatibility with previous hardware, where links
enabled write accesses to the 8 MByte Boot Area of Flash and the remaining User
Flash. These links now have no effect on the hardware interface to the Flash devices,
as all sector protection is controlled by software. See the
section for further details.

Table 2-6 Links P3 3-4 and 5-6

Link
Out
In

2.8 JTAG Scanbridge Enable Link (P4 1-2)

The IMP2B uses a JTAG Scanbridge device to connect all of the JTAG-compliant
devices on the board. This link is provided to enable the Scanbridge during test and
should not normally be fitted in deployed systems.

Table 2-7 Link P4 1-2

Link
Out
In
Publication No. IMP2B-0HH/5
NOTE
After the boot sequence, user software may alter sector protection at any time.
Meaning
Boot/User Flash sectors are write-protected by default
Boot/User Flash sectors are write-enabled by default
CAUTION
P3 3-4 and/or P3 5-6 out provides no hardware write protection. Software provides all Flash write
protection
Function
JTAG Scanbridge disabled
JTAG Scanbridge enabled
Configuration Register 1.
Flash Sector Protection
Configuration 13