Documentation:NGW/NGW100 Memories
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Contents |
[edit] Overview
[edit] Block diagram
The memory hierarchy of the Network Gateway with the Linux mouting points is shown in the block diagram below.
[edit] SDRAM
The SDRAM on the Network Gateway is 256 Mbit (4M x 16 bits x 4 banks) or 32MB, with a 16 bit bus to the AP7000.
Memory parameters:
| Number of columns | 512 (9 bit) |
| Number of rows | 8k (13 bit) |
| Number of banks | 4 (2 bit) |
| CAS latency | 2 |
| Refresh rate | 15.6uS |
| Recovery time | 2ck |
[edit] Parallel flash
The boot flash is a 64 Mbit (8MB) flash with a 16 bit bus to AP7000.
The parallel flash is preloaded with U-Boot and an embedded Linux environment.
[edit] Serial data flash
The serial data flash is attached to AP7000's SPI0 interface (CS0) and is preloaded with the Linux file system. (Program and data for the Network gateway functionality)
[edit] Disk Space Layout
The df command show the layout and the available space.
/ $ df Filesystem 1k-blocks Used Available Use% Mounted on /dev/root 8000 6688 1312 84% / 8M Parallel Flash dev 15468 0 15468 0% /dev 16M RAM Drive tmp 15468 0 15468 0% /tmp 16M RAM Drive run 15468 24 15444 0% /var/run 16M RAM Drive samba 15468 236 15232 2% /var/lib/samba 16M RAM Drive log 15468 68 15400 0% /var/log 16M RAM Drive /dev/mmcblk0p1 31075 1 31074 0% /media/mmcblk0p1 SD/MMC Card /dev/mtdblock3 8448 8180 268 97% /usr 8M Serial Flash
Note that the Serial Flash Drive is a lot slower then the Parallel Flash. This is why when you go to the Documnet page for samba it takes a long time to display the page.
The /etc and /home are Mounted on the Parallel Flash memory, and the log files are mounted on the RAM Drive
