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Compact Flash adapter

jknightandkarr

Experienced Member
Joined
Nov 10, 2023
Messages
65
I saw on Adrian's Digital Basement, he had one of those NOS Green 753s and used a compact flash adapter in it, which worked, anyone have links to known good ones? I have 2, tested 1, haven tried the other yet, it didn't work in my Z-Star Ex at all, and don't expect it to work either.
 
CF to IDE adapters are entirely passive, they're nothing more than an interface converter.

Your problem is going to be the CF card. A CF card is an LBA block device, and requires an IDE controller that supports LBA for it to be addressed. In early IDE, LBA was only an optional part of the specification and not all controllers support it. Anything pre-1996 is likely not going to support LBA, but there were some later machines that lacked LBA support.

There are some CF cards that have additional logic to present themselves to the host controller with a CHS addressing scheme, and do CHS to LBA translation in the CF card, but those are a bit difficult to find. If the BIOS in your machine has a USER type 47 in the hard drive selection, you can try and fudge numbers for the cylinders, heads (don't go over 255) and sectors to get the maximum possible capacity and see if it works. If that's not available, you can try to select one of the 46 drive types with the maximum capacity and see if that works.

Try to keep your drive size within reason, don't expect huge multi-gigabyte capacities to work. Your BIOS could have one of several int13h geometry limitations. If it entirely lacks LBA, it may be as low as 528 MB. There's a danger that fudging numbers too high could cause the BIOS to crash. There were some pretty terrible disk handling routines in some BIOS releases that weren't properly bounds checked and could cause stack smashing and either crash or cause extremely errant behavior. This goes double for the auto detect functionality, I've seen where the CHS values weren't bounds checked, and on large drives, they'd end up stack smashing due to writing values out of bounds and go off into lala land.

Something else you could try is a disk on module, which are often used in industrial boards. Just search for "IDE DOM" on Ebay and get a smaller one.
 
CF to IDE adapters are entirely passive, they're nothing more than an interface converter.

Your problem is going to be the CF card. A CF card is an LBA block device, and requires an IDE controller that supports LBA for it to be addressed. In early IDE, LBA was only an optional part of the specification and not all controllers support it. Anything pre-1996 is likely not going to support LBA, but there were some later machines that lacked LBA support.

There are some CF cards that have additional logic to present themselves to the host controller with a CHS addressing scheme, and do CHS to LBA translation in the CF card, but those are a bit difficult to find. If the BIOS in your machine has a USER type 47 in the hard drive selection, you can try and fudge numbers for the cylinders, heads (don't go over 255) and sectors to get the maximum possible capacity and see if it works. If that's not available, you can try to select one of the 46 drive types with the maximum capacity and see if that works.

Try to keep your drive size within reason, don't expect huge multi-gigabyte capacities to work. Your BIOS could have one of several int13h geometry limitations. If it entirely lacks LBA, it may be as low as 528 MB. There's a danger that fudging numbers too high could cause the BIOS to crash. There were some pretty terrible disk handling routines in some BIOS releases that weren't properly bounds checked and could cause stack smashing and either crash or cause extremely errant behavior. This goes double for the auto detect functionality, I've seen where the CHS values weren't bounds checked, and on large drives, they'd end up stack smashing due to writing values out of bounds and go off into lala land.

Something else you could try is a disk on module, which are often used in industrial boards. Just search for "IDE DOM" on Ebay and get a smaller one.
Thanks for all of the help. I will try the IDE DOM thing. Wish i knew about those for my Zenith Z-Star back in November when it went out.... >.<
 
Ok, I have the IDE DOMs and need an adapter. I guess can't just use male-to-male headers as apperently pinout is flipped/mirrored, so I found these on amazon. would these be whats needed? Thanks
Adapter 1
Adapter 2
 
If you can't stick them directly onto the IDE port as intended, you need an IDE extension cable.
 
I need one that fixes the pin flipping issue. I am not sure if what i found is whats needed or if i need to make a quick pcb design to fix it.
 
Those adapters just look like they rotate the connector 180 degrees. It wouldn't make any sense to mirror the pins any other way, because no IDE device does that.
 
I have 2, tested 1, haven tried the other yet, it didn't work in my Z-Star Ex at all, and don't expect it to work either.
You should try the other one as well. There's no quality control on these very cheaply made CF adapters. The one you tried might have a short somewhere due to a mistake in soldering and the other could work just fine.

That said, the BIOS in your machine is the most likely reason for it not working. There's a chance the DoM won't work either. If so, you might want to look into installing XTIDE Universal BIOS, if that's possible.
 
I will think about the custom bios, don't wanna screw it up permanently... lol i ordered an adapter, mentioned DOM so hope it works, all else fails I can diy it.
 
I will think about the custom bios, don't wanna screw it up permanently... lol i ordered an adapter, mentioned DOM so hope it works, all else fails I can diy it.

XTIDE "BIOS" is a bit of a misnomer. Despite being called a BIOS, it is an option ROM that patches the INT13h disk routines to handle larger drives (it also does other things depending on what build you use.) Since you have to burn it to a separate EEPROM and install it in something like a network card's boot ROM socket, you can simply remove it if it causes problems or doesn't work.

The problem in your case is you have a laptop. You'll have to find some device that allows you to install a ROM in it for the XTIDE BIOS to run from.
 
Why not use the correct CF card adapter? With a 3D printed adapter plate from Thingiverse they replace a 2.5" hdd in size too. Here's one of many on Amazon:

chenyang CF Compact Flash Merory Card to 2.5" 44Pin IDE Hard Disk Drive HDD SSD Adapter for Laptop​

 
The Green 753 laptop BIOS allows up to an 8GB HDD before needing Ontrak overlay. Most likely any CF card will also need software update so that BIOS sees it as a HDD and not as a removable device (not bootable) and a RUFUS D/L can do this plus, if wanted, will load FreeDOS too.
 
The 8GB limit thing has been a bit confusing - I ended up purchasing an 8GB SD card and an SD to IDE adapter for the Green753, should work, right? Didn't. Capacity was detected as 8000 something megabytes and then software didn't work with it properly. I highly doubt this was an issue with the SD adapter. So, will it even work with an 8GB card, or will it need UNDER 8GB, in which, if using solid state storage you're stuck stepping down to 4GB. I do need to experiment more around with OnTrack though.
I personally prefer SD rather than CF because CF cards are always SO expensive. No matter what the size. I don't want to pay $15 for a 256MB card that would take cents to manufacture today. I get why, I doubt they're made anymore, probably NOS, but still.
 
I went with CF cards mostly because I have a couple of PCMCIA adapters that use CF cards. I haven't explored the exact limit of the hard drive size to see if it is 8GB or under 8GB's since I mostly use 2GB CF cards - I have a stack of them I bought some time ago. I have a unique device installed in one old PC tower that takes a 2.5" HDD in a module and using a CF card in a USB adapter I've copied Windows from a couple of old 2.5" HDD's over to the CF's. Testing the Green 753 drive limit is something I guess I should try soon. That's how I got around the PITA method loading Windows to a Green 753 when the 753's CD drive doesn't want to read a burnt CD.

I do have a few larger CF's, but I've been using them in other laptops that aren't as touchy as the Green 753 for drives, but do need a cheap 2.5" PATA HDD. But I've also been using MSATA SSD's with adapters when the max size limit isn't an issue for many of these other laptops.
 
Why not use the correct CF card adapter? With a 3D printed adapter plate from Thingiverse they replace a 2.5" hdd in size too. Here's one of many on Amazon:

chenyang CF Compact Flash Merory Card to 2.5" 44Pin IDE Hard Disk Drive HDD SSD Adapter for Laptop​

2024-02-2421.20.463113663990663014884.jpg
Is this the one? Link didn't work... I have 2 diff ones, haven't tried the other, but will download software to try and make the CF card work. Haven't been able to get on forums at all Norton 360 for gamers is blocking forums saying they are dangerous??... so had to use phone.
The Green 753 laptop BIOS allows up to an 8GB HDD before needing Ontrak overlay. Most likely any CF card will also need software update so that BIOS sees it as a HDD and not as a removable device (not bootable) and a RUFUS D/L can do this plus, if wanted, will load FreeDOS too.
 
XTIDE "BIOS" is a bit of a misnomer. Despite being called a BIOS, it is an option ROM that patches the INT13h disk routines to handle larger drives (it also does other things depending on what build you use.)
My understanding is that if a call is made to an INT13 BIOS function, and the target drive is within the scope of the XTIDE Universal BIOS (XUB), and the XUB supports that function, that the call is redirected through to the XUB's version of the INT13 BIOS function. If so, then a portion of the XUB code is providing 'BIOS' functionality.
 
My understanding is that if a call is made to an INT13 BIOS function, and the target drive is within the scope of the XTIDE Universal BIOS (XUB), and the XUB supports that function, that the call is redirected through to the XUB's version of the INT13 BIOS function. If so, then a portion of the XUB code is providing 'BIOS' functionality.

That's how an option ROM works. XTIDE is hooking INT13h and when the disk subsystem is requested, the XTIDE takes control from the BIOS and uses its own routines instead of the system BIOS. It hands control back when its done with whatever operation it was requested to do.
 
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