Back in 1994 I found an articale for a 4MB solid-state hard drive in ELEKTOR/ november issue. I've been wondering if I could use 2 x 512MB dimms on a PCI card to emulate a hard drive. The card should have battery backup and be BOOTABLE. WHERE DO I START ? I will appreciate ANY input to this project and WILL make the final design available to ALL who have contributed. THANX
interested ? EMAIL: hdougla@eng.uct.ac.za
and the translation it employs as the mode changes
when the bios does the post
the geometery is loaded to the shadow or to the bios ram
for exicution
it then {assuming you set the details other than auto mode or it queries the controller on the hdd for the geometary string to be sent from the now loaded core on the hdd {loads to the hdd bus controller chip} once this string inisialises the bus flags
the controllers registers
like
mode sector tracks landing zone etc
say udma 166550 256 65535 0 ...
master bus controller reads them and sets up the mode of translations as the o/s boots
it uses a little memory array to set the flags and passes this to the post bios app that is running like an exe in its own o/s {the bios boot block}
each time {much like a modem employs the two laders and the guy in the middle approch to boot up the speeds
is how the whole of this wintendo system works}}
so.... knowing these few things is the start of a worthwhile project
why you dont just buffer an 512 mb sdram add a few batteries and a pic boot from this
NO! you can't. Thats dynamic ram, you need flash! Go for the usb dongle solution.
A few dedicated chips are about, like ST72F651, optomised for flash card i/f, full speed usb. I'm working on one at the moment. Enumerates as a drive, stores 64M on flash, fits in your pocket.
Whoops, didn't read your post carefully enough. U r talking about a bootable pci card.
A place to start is 'open cores', search for it with google. Open source hdl code for a pci interface you can load into an FPGA.
Place to start?
You would require.
1. Patching the BIOS to read from the PCI card rather than from teh IDE interface.
2. keeping the DRAM refreshed every few milliseconds.
3. Implementing interface and dirver for motherboard.
I would suggest using a Compact Flash card connected to the IDE interface.
The best speed can be reach when you connect the CF card to IDE with PIO4 enable . Our current CF product's write spped can be as high as 4.7MB/s on PC. The read speed can be maxmize upto 10MB/s when use the USB2 card reader in true IDE mode. With MMC/SD SPI mode , it's very slow . Most of the PDA use this mode to access SD/MMC . But you lost a lot in speed .
You can get CompactFlash cards up to 1 GB. If you download the file CompactFlash2ide.rar which I have uploaded in this topic: **broken link removed** then you can interface your CompactFlash to the IDE-interface. It is very easy to connect and seems to be the best solution for your purpose.