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4.8
Local Bus Interface
The MVME7100 uses the MC864xD Local Bus Controller (LBC) for access to on-board flash and
I/O registers. The LBC has programmable timing modes to support devices of different access
times, as well as device widths of 8, 16, and 32 bits. The MVME7100 uses the LBC in GPCM
mode to interface to two physical banks of on-board flash, an on-board Quad UART (QUART),
an MRAM, and on-board 32-bit timers along with control/status registers. Access timing for
each device type is programmable and depends on the device timing data found in the VPD
during initialization.
A hardware flash bank write protect switch is provided on the MVME7100 to enable write
protection of the NOR Flash. Regardless of the state of the software flash write protect bit in
the NOR Flash Control/Status register, write protection is enabled when this switch is ON.
When this switch is OFF, write protection is controlled by the state of the software flash write
protect bits and can only be disabled by clearing this bit in the NOR Flash Control/Status
register. Note that the F_WE_HW bit reflects the state of the switch and is only software
readable whereas the F_WP_SW bit supports both read and write operations.
The MVME7100 provides a dual boot option for booting from one of two separate boot images
in the boot flash bank which are referred to as boot block A and boot block B. Boot blocks A and
B are each 1 MB in size and are located at the top (highest address) 2 MB of the boot flash
memory space. Block A is located at the highest 1 MB block and block B is the next highest 1
MB block. A flash boot block switch is used to select between boot block A and boot block B.
When the switch is OFF, the flash memory map is normal and block A is selected as shown in
Figure 3. When the switch is ON, block B is mapped to the highest address as shown in Figure
4. The MAP_SELECT bit in the flash Control/Status register can disable the jumper and restore
the memory map to the normal configuration with block A selected.
4.8.1
Flash Memory
The MVME7100 is designed to provide 128 MB of soldered-on NOR flash memory. Two AMD
+3.3 V devices are configured to operate in 16-bit mode to form a 32-bit flash bank. This flash
bank is also the boot bank and is connected to LBC Chip Select 0 and 1.
Also included is a second bank of NAND flash, up to 32 GB, connected to LBC Chip Select 2. The
VPD flash packet(s) will determine which devices are populated and the size of the devices.
Programming details can be found in the MVME7100 Single Board Computer Programmer's
Reference manual.
MVME7100 Single Board Computer Installation and Use (6806800E08C)
Functional Description
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