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Let me begin from how i come to asking about this . Yesterday i was talking to my brother . As always eager to try every new gadget for pc's ,he wanted to see if he could instal vista on memory card and boot from it like from a hard disc. Now is my question - Did any of you see schematics of how to connect big ramdisks to ata or s-ata ports with a 8051. I assume it would be possible with SD cards or maybe even DDR2 with battery backup bcoz 8051 has port pins .
I hope you could shed some light on how to build this .
Have a nice eve Walkura
You seem to be mixing and matching.
In many cases, a RAM-disk is just a device driver allocating parts of your work-memory RAM into a virtual disk. No much different from caching of a real disk, but reduces fragmentation of the HDD and is faster since the normal disk caching will regularly write down changes to make them survive a power loss.
You can buy expensive, external, RAM-disk boards with a lot of memory and often a memory backup. But they are only useful if they have a very, very high bandwidth. Any solid-state memory will have way better seek times than a normal HDD, but to be meaningful, the transfer rates must also be at least close to the transfer rates of a HDD.
Do you expect that a 8051 processor can manage 50MB/s? Even 10MB/s is a very high data speed for an 8-bit processor.
In this case, it would be better to just connect a flash memory. It takes a very simple and cheap adapter to connect a CF memory to a PATA connector - the signals on the CF memory are almost identical, since the PATA connector came with the IDE - Integrated Drive Electronics - standard, where you basically connect the HDD directly to the PC AT bus. And a CF card is designed to connect to a subset of the PC AT bus, since it is intended for use in PCMCIA slots.