Fujitsu still makes computer components? I thought they only made Self-scan machines (U-scan) only. Weird, yet interesting.

Ozzuneoj wrote:

What would I gain from using a $20 512MB DOM versus a $7 512MB "Industrial Grade" CF card?

I see that DOMs are often marked as having SLC NAND, which is good (faster and longer life), but what do CF cards generally use and does it even matter on systems that were originally using incredibly slow hard drives? Consumer grade SSDs haven't used SLC NAND for years. They're almost all MLC or some variant (TLC, 3D-something-or-other, etc.) and it hasn't stopped them from being faster than most people really need.

EDIT: Heh, post right before mine covered some of this. But more input would still be appreciated. 😊

Another poster already mentioned the fixed/removable drive status of the two, so I won’t go into software differences.

Physically, the only thing you really gain is a native PATA connector on the DOM, so you don’t need to use a CF to IDE adapter. Personally, I prefer using a CF to IDE adapter, as you have many more mounting choices (3.5” bay, card slot adapter, direct IDE male or cable to IDE female, 2.5” drive adapter, etc.) which makes data exchange much easier with a modern PC, as you can just pop the card into a USB 3 CF reader. Sure, you could open the PC up and pull the IDE DOM out, then hook it to a USB 2.0 IDE cable, but that’s more work!

I find being able to easily access the CF card means I make images of it more often, which is a good thing. (My main system is a MacBook, so making a raw image is as simple as typing “sudo dd if=/dev/rdiskN of=~/cf-backup.img bs=1m” in Terminal and waiting 30 seconds, normally I pipe the image through 7-Zip as well to compress it; the same method works in Linux and there’s Windows software that will do this as well.) If you make semi-regular images of your CF cards, it doesn’t really matter if they die at some point (though I’ve yet to have one die).

As for the type of flash CF uses, well, it depends on the card. Consumer oriented CF (this will be your basic Transcend and SanDisk cards) almost exclusively uses MLC flash. Most of the Transcend and SanDisk Industrial cards over 1GB or so also use MLC flash, they just use more agressive wear leveling algorithms and contain extra flash cells (sometimes 25 to 50% more) to take the place of worn out cells. This is generally how the low end modern MLC SSDs work as well. (MLC flash has come a long way in the last 8 years too, so it’s a lot more reliable than it once was, still, it has limits.)

Now, the *real* Industrial CF makers (SwissBit, Delkin, pQI, etc.) generally use SLC *plus* the aforementioned added flash cells and aggressive wear leveling. These SLC cards are available from 128MB to 64GB. Some manufacturers offer MLC variants of these cards (generally the higher capacity—over 16GB—models) to keep the price down for less demanding applications, so check the part number. (For example, SwissBit only makes SLC cards; Delkin makes mostly SLC but does offer MLC on one model.) These manufactures will have datasheets or catalogs available on their sites with keys that will allow you to decipher the part numbers, which is handy when buying used cards from eBay.

If you do buy from eBay, stay away from *new* Wintec, SanDisk and Transcends cards as thea).ey’re almost always counterfeit junk. Clearly used cards should be OK, but I prefer to go with one of the boutique industrial manufacturers; SwissBit is my personal favorite (you can get some *very* good deals on lots of 8GB SwissBit cards, some of which still sell brand new on Mouser for $200/each); these generally have 75% or more of their life remaining, as they were used in routers or other industrial SBCs and generally saw very little write activity.

Now, let’s talk speed! First off, let’s look at consumer oriented cards: The SanDisk Ultra and Transcend 333x cards advertise flashy numbers, but they’re *very* conditional. They’re also specifically geared towards write speed, very much at the expense of read performance. That’s perfect considering what they’re designed for: DSLR cameras! When you’re taking photos in burst mode (5+ 25MiB pictures per second) or 60FPS 1080p video, you need a storage medium that can keep up. However, read performance is often quite underwhelming compared to write performance.

Now, wih industrial cards there’s normally multiple families in a series, so the speeds vary depending on the model, however they almost always start out at 20MB/s write, 40MB/s read, 60MB/s burst speed and go up from there. These speeds are consistent across conditions and guaranteed. The older SLC based industrial cards can max out an ATA-33 interface, so they’re perfect for anything from a Pentium down to an 8086.

If you have a higher end system (a Pentium Pro or PII perhaps) and want faster performance, consider a PCI raid card and two or four CF in RAID-0 (Striping). If you can find a Promise ATA-66 PCI card on eBay cheaper than a real IDE RAID card, it can be converted to a RAID by simply unsoldering a resistor and flashing different BIOS to the card. (I actuslly did this back in 2000 and boy did scream!) Right now I’m in the process of a getting additional parts together for a Dual P2-400 build and I’ll be using four 8GB SwissBit CF cards in RAID-0; I can’t wait to see what the hard drive benchmarks show!

Also, keep in mind that either option (consumer or industrial Cf) is going to *feel* a hell of a lot faster than any mechanical drive (even high end 10k or 15k RPM Ultra-SCSI drives), even if the actual speed is slower, especially under Windows 9x, due to one simple fact: Latency! It takes, at a minimum, 10’s of milliseconds for the head to move to the correct spot on the platter, whereas CF can access any data in 100’s of microseconds, several orders of magnitude difference! Even if you keep your mechanical drive defragmented, that only helps for sequential reads and writes, not random access.

Hopefully this answered some of questions, and if you need help deciphering the part numbers of some of industrial CF let me know, I’d be glad to help! (Some of the manufacturer’s require verified registration before allowing you to download datasheets {Delkin, I’m looking at you!}, which can be nearly impossible as an individual.)

HDD's seek time is generally 8-12ms, not 100s of milliseconds.

Good SSD access time is generally about 0.1ms, which is 100,000 nanoseconds. (May be faster as not sure if that measurement is a limit of the testing software).

cyclone3d wrote:

HDD's seek time is generally 8-12ms, not 100s of milliseconds.

Good SSD access time is generally about 0.1ms, which is 100,000 nanoseconds. (May be faster as not sure if that measurement is a limit of the testing software).

Whoops, that’s should have read “10’s of milliseconds” and yes, I should have said micro instead of nano. I spent all day measuring nanovolts, so “nano” must be stuck in my brain. Sorry about that, fixed now.

Coming back to old thread!

Finally got some IDE DOMs. Not the cheapest option but reading the thread, browsing eBay, that seemed the solution I want to use. Thanks for all the suggestions!

Just want to point out one small thing which might matter but is easy to miss when making an order: many (most/all?) IDE DOMs plug straight into motherboard (as they have a female connector) and might not have a slave/master jumper. Not a big deal, if there are enough IDE channels available on the motherboard. In case many IDE devices are needed, one workaround to this issue (which I have not yet tried) is to use 40 pin IDE gender changer, and set the other device on the same channel as slave.

EDIT: I just realised the type of adapter I've linked will not work, as the end result will be that every odd pin of the DOM will be connected to even and vice versa... what is needed is this kind of adapter, with two male connectors. I suppose you could put a male connector into a IDE cable, if you have the tools, but I'm not sure what kind of connector works best with UDMA cables ...