It has been a long time since this topic was updated, but I see several people were left hanging last time it was written to. I'm trying to help someone with one of these now and thought I'd update this with some more specific instructions.
I have a working MT8801B. I was able to successfully boot from another card copied using this method. If anyone needs my image file, it's at
https://drive.google.com/file/d/1gD18akCZ9pAuFuSvc5z9VU1CvOkLJnCa/view?usp=sharing - my system has options 1, 2, and 7 enabled. I don't know if option enabling is done through the boot image or through static memory on the system.
[this is what I did to get the disk image, I am using an old Windows 2000 laptop with an integrated PCMCIA reader and a legacy copy of HxD on this machine]
Use "Open Disk" which is under the "Extras" in HxD to open the logical drive you are trying to copy. In the new version of HxD, "Open disk" is under "Tools." Make sure "read only" is checked so you don't accidentally overwrite anything. Open the disk and save its contents to a file.
[writing the disk image, again I'm using an old version of HxD so there may be slight variations in the menu]
I am not familiar enough with the intricacies of disks to know if makes a difference [it almost definitely does not], but I formatted the drive anew as a FAT16 drive before writing.
First, open the image file using HxD. Select all, then copy to clipboard.
Open your new card under "Tools." You will be looking under the "physical disks" heading, not "logical disks." For this to work you need two things: 1) no mounted file system on the drive you want to write to, unmount any mounted file systems for that drive. 2) card should not be accessed using USB hub [apparently some users have this issue with HxD].
BE VERY SURE YOU ARE OPENING THE CARD AND NOT YOUR HARD DRIVE, SECONDARY HARD DRIVE, OR OTHER PERIPHERAL DEVICE CONNECTED TO YOUR COMPUTEROn HxD after opening the drive you want to prepare with "read only" unchecked I then started at 00000000x0 (the top left), then under the edit menu selected "Paste Write." It asked me to confirm, which I did. I then saved, closed HxD, ejected the drive (it did not let me do this until all data was written), then removed the drive and booted it on my Anritsu.
There was other data remaining on the card I was writing to after the pasted data - I did not need to clear it out.