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Keatah

Putting together an Am5x86 rig.

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On 5/5/2020 at 12:49 AM, Keatah said:

Think I found another solution. It will have to wait for parts to get here in June. Covid19 and all that.. So while we wait I was thinking about CF or SD card interfaces.

 

What would be a good way to do this? There seem to be 6 or 7 ways. And I've narrowed it down to:

 

https://www.ebay.com/itm/SD-SDHC-SDXC-MMC-Card-to-IDE-40Pin-3-5inch-Male-Adapter/123457150544

https://www.ebay.com/itm/SODIAL-R-44-Pin-Male-IDE-To-SD-Card-Adapter-DT/252470736918

https://www.ebay.com/itm/XT-IDE-Deluxe-Bootable-ISA-CF-IDE-Interface-Card-with-IBM-XT-Slot-8-Support/124122830301

 

I plan on doing one on this machine and my older original 486 Gateway machine. On this "new" build I suppose I would need the XT-BIOS card for the BIOS.

 

Did you ever try any of these?   I'm thinking about buying an IDE to SD converter for an old PC, since those old IDE drives won't last forever.

 

But every IDE to SD adaptor I've looked at seems to have 4 screw mounting holes, with nothing in the description of what they mount to.   Are they the same screw arrangement as a 2.5" drive?   I really don't want one of these boards dangling freely inside the case, I want to make sure I can mount it.

 

 

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4 hours ago, zzip said:

Did you ever try any of these?   I'm thinking about buying an IDE to SD converter for an old PC, since those old IDE drives won't last forever.

https://www.ebay.com/itm/XT-IDE-Deluxe-Bootable-ISA-CF-IDE-Interface-Card-with-IBM-XT-Slot-8-Support/124122830301

It works as advertised and is versatile. It is but one of several projects and iterations of integrating the XT-IDE BIOS into a PC that doesn't support big disks.

 

Some projects are for boards both with and without actual IDE connectors. This one can act as a controller for real mechanical HDD too.

 

I use it my original 486, and the Am5x86 rig I put together. The BIOS worked well. It could potentially test your knowledge of BIOS and disk formats and limitations and how they apply to Compact Flash. But that's me and I had to brush up on the material. Out of the box it booted straight away into FreeDOS

 

In practical use though - inserting a CF card into the back of a machine, blindly, can be temperamental till you learn exactly how. It's just the way of things. An annoyance because you have to line it up. Just. So. As bad as USB, having to try THREE times before it plugs in!

 

Quote

But every IDE to SD adaptor I've looked at seems to have 4 screw mounting holes, with nothing in the description of what they mount to.   Are they the same screw arrangement as a 2.5" drive?   I really don't want one of these boards dangling freely inside the case, I want to make sure I can mount it.

 

https://www.ebay.com/itm/SD-SDHC-SDXC-MMC-Card-to-IDE-40Pin-3-5inch-Male-Adapter/123457150544

..can be mounted like this..

https://www.ebay.com/itm/PCI-bracket-with-SD-to-IDE-drive-adapter/303596155608

..or like this..

https://www.ebay.com/itm/3-5-floppy-drive-bay-SD-to-IDE-hard-drive-carrier-adapter-40-pin/303551644199

..or..

https://www.ebay.com/itm/PCI-bracket-for-SD-to-IDE-drive-adapter/303596143604

 

And this one I haven't played with yet or mounted.

https://www.ebay.com/itm/SODIAL-R-44-Pin-Male-IDE-To-SD-Card-Adapter-DT/252470736918

But it appears to just plug into a connector/adapter for internal use and that is that!

 

I'm not opposed to taking a failed 3.5" drive's housing and either 3D printing spacers and mounts to secure ones of those adapters inside it. Or just build-up something with scrap plastic and epoxy. Something I've done before to shore up laptop screw holes and other cracked plastics. A gutted 3.5" drive housing would give you ample room internally and provide nice access to the slot. And you could fill the side gaps with RGB!

 

Don't forget to consider a DOM. It may have better write endurance being MLC (or in more expensive versions, SLC) than what recently made SD cards offer.

https://www.ebay.com/itm/512MB-HyperDisk-DOM-Disk-On-Module-Industrial-IDE-Flash-Memory-40-Pins-SLC/221178581875

 

MLC should get you 5,000 - 10,000 re-writes (P/E cycles) to any one given cell or block of cells. And SLC takes that to 100,000.

 

TLC and QLC can be as shitty as 600 writes and that's it! A rule of thumb is the older and smaller the capacity, the longer-lived a flash device is.

 

And of course reads are unlimited.

Edited by Keatah

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12 hours ago, Keatah said:

https://www.ebay.com/itm/XT-IDE-Deluxe-Bootable-ISA-CF-IDE-Interface-Card-with-IBM-XT-Slot-8-Support/124122830301

It works as advertised and is versatile. It is but one of several projects and iterations of integrating the XT-IDE BIOS into a PC that doesn't support big disks.

 

Some projects are for boards both with and without actual IDE connectors. This one can act as a controller for real mechanical HDD too.

 

I use it my original 486, and the Am5x86 rig I put together. The BIOS worked well. It could potentially test your knowledge of BIOS and disk formats and limitations and how they apply to Compact Flash. But that's me and I had to brush up on the material. Out of the box it booted straight away into FreeDOS

 

That one is tempting,  but I only have 2 Compact Flash cards,  while I have a pile of unused SD cards in the 512mb - 2Gb range.  So I'm leaning towards getting an SD one,  although I know that CF is a more natural fit for this since it's basically an IDE device already.

 

I was wondering how disk geometry works given that these devices don't have physical heads/tracks.    One video I watched suggested downloading a DOS app named "WHATIDE.EXE", if BIOS doesn't detect it properly

12 hours ago, Keatah said:

Cool, I didn't realize you could get a rear mount for the SD ones

 

12 hours ago, Keatah said:

Don't forget to consider a DOM. It may have better write endurance being MLC (or in more expensive versions, SLC) than what recently made SD cards offer.

https://www.ebay.com/itm/512MB-HyperDisk-DOM-Disk-On-Module-Industrial-IDE-Flash-Memory-40-Pins-SLC/221178581875

I don't see the two systems I'm considering these for to having heavy writes,  and no critical data (maybe old Dos games and old versions of Windows),  so if one of these fails,  I have plenty of spare SD cards

 

12 hours ago, Keatah said:

TLC and QLC can be as shitty as 600 writes and that's it! A rule of thumb is the older and smaller the capacity, the longer-lived a flash device is.

I thought it was the opposite?   With wear-levelling in modern NAND, the bigger the drive, the more spare capacity and the better the longevity--  unless you are a maniac and rewriting the entire drive regularly

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6 hours ago, zzip said:

I thought it was the opposite?   With wear-levelling in modern NAND, the bigger the drive, the more spare capacity and the better the longevity--  unless you are a maniac and rewriting the entire drive regularly

That's right. It depends on which angle you approach the problem.

 

The bigger the drive the more free space is available to the drive for wear leveling, provided you actually have left some space available for the drive to do its thing.

 

Let's say you have a 1 TB SSD, and you only use 100GB. Now you have 900GB left for wear leveling. And if you never use more than 100GB, you suddenly increased the writable lifespan 9x over!

 

If you fill it to 500, You have still increased it 5x. All of that in addition to overprovision provided by the manufacturer. This would be spare sectors not available to the user, ever. Never ever. And it's usually between 1 and 10% of the total size.

 

And if you top it off to the max, then you're at 1x. When full the following write limits would apply to each block.

 

P/E cycles

SLC = 100,000+

MLC = 10,000 - 20,000

TLC = 2,000 - 5,000

QLC = 600 - 3,000

PLC = 200 - 700

HLC = 50 - 350

 

It is also important to know there is some write amplification. To edit/save a 1K byte text file, you have to erase the surrounding 64K block for example. So writing 1K uses more writes internally than just 1K, as the drive rearranges old data.

 

There's a lot of tricks and trade secrets involved with how the firmware handles all this. And with 3D V-NAND and those tricks, along with never filling a drive to the brim, you'll get a long life.

 

Thankfully the mfgs boil it down for you to an easy to understand spec that works. TBW - Total bytes written. Or expressed another way, Total Drive Writes - how many times can you write and erase a full drive before it locks into read-only or fails entirely.

 

Hope that makes some sort of sense.

Edited by Keatah

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22 minutes ago, Keatah said:

Let's say you have a 1 TB SSD, and you only use 100GB. Now you have 900GB left for wear leveling. And if you never use more than 100GB, you suddenly increased the writable lifespan 9x over!

When I partitioned my 1TB SSD, I purposely left some space unpartitioned because I heard they slow down quite a bit when they are almost full, so I don't anticipate wearing it out anytime soon :)

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That should do the trick. The controller doesn't care about partitions. In this context of wear leveling it only cares about blocks on the drive and their accumulated writes.

 

SSDs are still quite amazing, to the 8-yr old in me. They're like those SuperMan crystals. And they are indeed lab-grown Silicon crystals. Aren't they..

 

 

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46 minutes ago, Keatah said:

That should do the trick. The controller doesn't care about partitions. In this context of wear leveling it only cares about blocks on the drive and their accumulated writes.

Yeah, I assumed the wear-levelling firmware wouldn't even be aware of the partition table.  Sounds like it was a safe bet!

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On 9/16/2020 at 8:34 PM, Keatah said:

Just received one of these.  Put it on my secondary IDE, and could not detect it.  Then I realized my BIOS only supports primary IDE for hard drives.   There's no master/slave jumper,  so I couldn't set this up as drive D on this mobo,  so I guess I'll have to reinstall DOS/Windows on it to see what it can do.

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1 hour ago, zzip said:

Just received one of these.  Put it on my secondary IDE, and could not detect it.  Then I realized my BIOS only supports primary IDE for hard drives.   There's no master/slave jumper,  so I couldn't set this up as drive D on this mobo,  so I guess I'll have to reinstall DOS/Windows on it to see what it can do.

Or get one of those dreaded Promise IDE controllers (or similar, I believe XT IDE also does INT13 interrogation and population) that has its own detection routine baked in.

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29 minutes ago, wierd_w said:

Or get one of those dreaded Promise IDE controllers (or similar, I believe XT IDE also does INT13 interrogation and population) that has its own detection routine baked in.

probably not worth it for this system, it's only going to have 1 hard drive and one CD-ROM in the end.  The CD-ROM works fine on the secondary.    The hard drive in there now is over 20 years old and could fail anytime, so these devices seem like a good substitute for that eventuality.

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