VULCAN Technical Manual
Detailed hardware description
© 2007 Eurotech Ltd Issue D
28
Memory
The VULCAN has three types of memory fitted:
•
16 or 32 Mbytes of resident Flash disk containing Redboot (to boot the OS), the OS
and application images.
•
64 Mbytes of SDRAM for system memory.
•
256 Kbytes of SRAM.
Further details about each of these memory types are provided below:
Flash memory/silicon disk
The VULCAN supports 16 or 32 Mbytes of AMD MirrorBit Flash memory for the
RedBoot bootloader, OS and application images. The memory is arranged as 8M x 16
bits (128 megabit device) or as 16M x 16 bits (256 megabit device), respectively. Since
each Chip Select of the IXP425 expansion bus interface supports the Flash chips up to
8M x 16 bits (128 megabit), CS0# and CS1# lines with simple glue logic are used to
support the 256 megabit Flash device (F32 VULCAN variant).
The Flash memory array is divided into equally sized symmetrical sectors that are 32-
Kword in size. A 128 megabit device contains 256 sectors, and a 256 megabit device
contains 512 sectors.
Whenever you access the Flash memory, the Flash access LED illuminates.
SDRAM interface
VULCAN supports 64 Mbytes of SDRAM. The SDRAM is configured as 16M x 32 bits
by 2 devices with 4 internal banks of 4M x 16 bits.
These are surface mount devices soldered to the board and cannot be upgraded.
RedBoot automatically detects the amount of memory fitted to the board and
configures the SDRAM controller accordingly. The SDRAM controller operates at a
frequency of 133MHz.
Static RAM
The VULCAN has a 256KB SRAM device fitted, arranged as 256K x 8 bits.
The data in the SRAM can be made non-volatile by fitting an external battery to power
the device in the event of power loss on the main VULCAN 5V supply. For more
information, see
, page
.
