I'm new on this forum and have to admit that I have a particular joy in the 6502 CPU and its products of the late 70's.
So, to share some of my recent adventures on my old Superboard II disk-subsystem, here my story which I hope will be of interest.
In my high school years, I was a lucky owner of a Superboard II doing hardware and software projects like kids are doing this nowadays using Arduino SBC's.
Projects typical for the 8k Basic model 600 have been a 32k RAM extension, a modification to the VDU circuit to get full 32x32 characters on the TV screen, a Video character ROM modification for low resolution graphics directly out of the VDU Ram, a 2716 EPROM programmer, 256x256 hires monochrome graphics and other peripherical to get additional I/O’s.
A floppy disk system has been the ultimate project challenge, but the OS65 due to memory consumption and need for 8- or 5.25-inch drives was never a real option. When 3.5-inch floppy drives became more affordable, around end of 83, I wrote in 6502 code my own floppy disk operating system on paper in my notebook.
It used the self-made Elektor floppy disk controller card and a double sided YE-625 (Y-E Data Inc.) disk drive. Several month later, the system was running properly but became soon forgotten, when I got an early Atari 260ST a year later.

Only two diskettes survived which I was able to read back using some sampling devices a few years ago. But disk emulation didn't work error free at that time.
Getting the old disk content back to live and disassembling the operating system, it began finally to work, so I decided to clean up the code and remove some of the bugs.
As it was initially programmed to work on a YE-625 disk drive, I call it YE-DOS.

Recently, I spend some more time to document the System ROM's and code I've made at that time. As I do not have a Elektor floppy disk controller anymore, so I used my Win_OSI emulator to test and run the disk images, which can hold 156kb per side.
The Emulator is currently setup for the YE-OSI DOS disk images. A special Boot ROM was required and RAM memory in the upper region starting at $E000, where the disk operating system resides. This will allow max 40kb of free memory available all time.
At boot, start with "D" and Cold start. DIR will show files on disk and SEL 0 or SEL 2 will change drives.
Manuals and files are linked on my site.
I placed everything here: https://sites.google.com/view/osi-superboard-ii/home

Enjoy
Thomas

Welcome! My first machine was an unlicensed and slightly modified clone of the Superboard II - a friend of mine got the original article. I do remember D for disk, although I didn't have a disk system at all! D/C/W/M was the boot time prompt, I think.

Well done on recovering your original disks!

And thanks for sharing your site.

Thanks ! You mentioned a SB II clone as your first computer. Do you refer to a UK101 model, the only clone I´m aware of in the late 70´s. Would be intersting to know, if there have been others clones as well.

That right, the Compukit UK101. Bought as a kit (as the name implies!) and pretty much my first soldering. It didn't work, so I re-soldered every joint, and then it did work!

Over the last week I was asked by UK101 enthusiasts to take a look at video mode emulation for their favorite machine. In particular, the 64x16 standard mode was not supported by the disk operating system.
So I updated the emulator and YE-DOS code to run this disk OS on both machines. The default configuration can be selected from the system menu.
Thanks for the feedback
Thomas

Great, thanks!

(A friend of mine had a Superboard, and I much preferred my 64 column display! He also got a PR100 versus my TI-57...)