Volitile eSATA DDR2 Memory Bank: Baterry Backup

[shawn_eary]

For various reaons, I would rather not upgrade to a 64 bit Microsoft OS right now. Is there a cheap preferrably battery backed eSATA interface that allows me to plug in DDR2 sticks and use it just like a Hard Drive?

Doing this would allow me to have a really big RAMDISK and get around the 3 Gig barrier in Win 32 XP Pro?

BTW: Yes, I know that 2^32 = 4 Gigs, but for some reason, Microsoft has a problem with this definition. Besies, whoever said a 32 bit computer had to have a 32 bit address space. If I have 32 bit registers and a 32 bit data path but a 256 bit address space does that make my computer 256 bit? This 32bit vs 64 bit OS junk is in my oppinion mostly a marketing ploy...

 

[sminlal]

What you're describing is not a "RAMDISK". A RAMDISK is software that takes part of MAIN memory and makes it look like a disk drive. The device you're describing would not let you put the RAM into the machine's main memory address space.

What you're describing is a Solid State Disk that uses RAM instead of flash memory. Such a device wouldn't be nearly as fast as RAM in main memory since the system could only access it by copying chunks from the drive to main memory via the eSATA interface, and the latencies and transfer rates are far, far slower than that for main memory.

Marketing ploy or not, the only way to get the full benefit of the extra memory is either to go to a server OS that supports AWE (Address Windowing Extensions) running on a system that supports PAE (Physical Address Extensions), or use a 64-bit OS on a 64-bit CPU

BTW, the 3GB limit is because the top 1GB of space is reserved for the OS and memory windows for hardware such as video cards. The reason most 32-bits computers have a 32-bit address space is because the definition of "32 bits" means "32 bit registers", and registers are used to hold addresses. It's very awkward to deal with addresses larger than the register size - just ask any programmer who had to deal with 20-bit segment addresses in the original 16-bit Intel 8088/8086. The development world breathed a huge sigh of relief when Intel went to a 32-bit "flat" addressing model to break the 1MB barrier, and nobody wants to go back to a segmented addressing scheme when 64-bit hardware and software is widely available and so much easier to deal with.

 

[mindless728]

@OP, yeah...segmented addressing sucks, take a computer organization class where you learn assembly in college then come back and say we should use it (x86 arch)

 

[shawn_eary]

It's very awkward to deal with addresses larger than the register size - just ask any programmer who had to deal with 20-bit segment addresses in the original 16-bit Intel 8088/8086. The development world breathed a huge sigh of relief when Intel went to a 32-bit "flat" addressing model to break the 1MB barrier, and nobody wants to go back to a segmented addressing scheme when 64-bit hardware and software is widely available and so much easier to deal with.

I vaguely remember this segmented addressing. I'm just tried of Microsoft's games. In the old days, having the original 5.25 inch floppy meant you had the software license - It didn't matter where you bought the floppy from. Now days, buying used software is a bit dangerous...

 

[sminlal]

In the old days, having the original 5.25 inch floppy meant you had the software license.

Times change. In the 5-1/4 inch floppy days there was no "Internet" that made widespread copying of the software easy.

I suspect you'd have a different point of view if you tried to make a living from writing software...

 

[RetiredChief]

Concur with siminlal.
One minor correction - 32 bit does not reserve 1 Gig (4gig installed), but as you stated does subtract out addresses used for various MIMO's such as video cards. A video card with 512 M Video ram will only subtact out 512, leaving 3.2->3.4 gigs of available Ram. With a 1 gig video card the user will end up with sligthly less than 3 gigs. I only memtion this as there is some advantage to going with 4 gigs vs 3 gigs in a 32 bit system. Laptops that come with 3 gigs ram install (Almost the only way to get 32 bit on Laptops) using shared video memory will see a booast by going to 4 gigs.

Remembering old times: My 2nd computer was a store bought 386SX. Used a ramdrive. With a ramdrive, you loss all that is in Ramdrive when you reboot. However: How I do not know, But with this computer I could reboot and every thing in the RamDrive was still there. Wanted to update the bios chip, order one - wouldn't work. Talked to tech support and ended up sending the Computer back (Slightly out of warrenty). They ended up replacing the Proccessor and the bios chip - Lost my unique Ramdrive.

PS there were also 8 in floppies, My son had one.

 

[sminlal]

32 bit does not reserve 1 Gig (4gig installed), but as you stated does subtract out addresses used for various MIMO's such as video cards.

When I referred to the memory being "reserved" I meant that it's not available to 32-bit application programs. I think that's what the OP was complaining about when he mentioned the "3GB limit".

 

[RetiredChief]

sminial
I have 4 gigs installed, of which 3.325 Gigs is available for operating system and programs (Note I only have a 512 Meg GPU). Granted when vista loads that brings the total down below 3 gigs. However that would also be subtracted out from 3 gigs when only 3 gigs is installed. I may be wrong but I have not seen a fixed 1 Gig allocation subtracted.

Vista 32
4 gigs installed
Total = 3.325 Gigs
Cached = 2.392 Gigs
Free = 60 Megs

will check Win 7 to see. But I have to reboot.

 

[sminlal]

I may be wrong but I have not seen a fixed 1 Gig allocation subtracted.

I'm referring to the amount of memory that's usable by each application program. See: http://msdn.microsoft.com/en-us/library/aa366778%28VS.85%29.aspx, and look at the first row in the table labelled "User-mode virtual address space for each 32-bit process". For a 32-bit process in a 32-bit OS, the limit is 2GB, or 3GB if the image is flagged as being able to handle large addresses. This is an architectural issue and has nothing to do with how much physical memory is installed or how much address space is used by hardware.

 

[RetiredChief]

Thanks

Added
OK read that - But I think that is the max for an individual 32 bit process, You may run multiple processes.
Quote "User-mode virtual address space for each 32-bit process"
Not many individual 32 bit procces will even come close to that limit there are a few memory hogs that will try to take all avail memory ie photoshop.

Win 7
4 gigs installed
Total = 3.326 Gigs (Same as Vista SP 1)
Cached = 755
Avail = 2.319 (Not listed in Vista)
Free = 1.794 Megs

 

[sminlal]

OK read that - But I think that is the max for an individual 32 bit process, You may run multiple processes.

Of course, I'm totally with you there. I was just trying to explain to the original poster the reasons for the "3GB limit" that he was complaining about.

 

[RetiredChief]

Great

 

[shawn_eary]

I suspect you'd have a different point of view if you tried to make a living from writing software...

I doubt it,
1) I have a Bachelor's of Science (Major: Computer Science)
2) I have been writting programs professionally for more than 7 years.
and I still think Microsoft's EULA's are ridiculous...

In regards to piracy, I am intrisically opposed to that. As a fellow software developer, I do everything I can to ensure that software is legally used. This, however, doesn't change the fact that I think Microsoft has gone waaaay overboard. In fact, I don't even think many Microsoft employees follow the Microsoft EULA's...