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I made my own DOS implementation (Announce)

posted by samwdpckr, 16.03.2024, 23:11

Why don't you just run the SETUP program as instructed in the documentation?

Of course it stops booting, if you mess up the boot sector with FreeDOS's FDISK. Don't do that.

It is a documented thing that ST-DOS (or rather its bootloader) does not currently support booting from a partitioned disk. The SETUP program creates a filesystem that starts from the first sector of the disk. FreeDOS on the other hand is hardcoded to assume that a hard disk always has MS-DOS-compatible partition table.

The SETUP program is hardcoded to always use C: as the target drive, which makes it impossible to install ST-DOS on computers that don't have a floppy drive. ST-DOS always starts counting drive letters from A:, and when it is booted from an USB storage stick on a computer that does not have floppy drives, the USB storage stick usually becomes drive A: and the first hard disk becomes B:. This problem does not affect VirtualBox users, because VirtualBox does not support booting from USB anyway.

I have purposely made the SETUP program in such way that it has as few options as possible, because for some reason people just cannot choose the right options even when it should be obvious what to choose. Seems that everything still has too much options.

There is no "Win3" UI and the TEXTEDIT program does not have vi mode. Almost nothing in your messages make any sense.

On DOS the TEXTEDIT program sometimes corrupts the files for some reason, when the caret position is on the second column and backspace is pressed. I haven't found the cause of that bug yet. The POSIX port of it works correctly, which makes it difficult to debug. Because the graphical interface has the NOTEPAD program, it is not a big issue.

For some reason FreeDOS's CHKDSK shows errors in the floppy disk image, but the directory entry for COMMAND.LNK in the \LEETOS\DESKTOP\ directory has its size just right and it is not 0 bytes. CHKDSK nor SCANDISK from MS-DOS 6.22 don't show any errors. I need to write my own CHKDSK program in the near future.

I fixed two memory bugs from the kernel. There were two pointers that were supposed to be far pointers to far pointers, but they were instead near pointers to far pointers. That caused the kernel to save the pointers to int23h and int24h interrupt handlers to its own stack instead of the PSP of the currently running program.

ST-DOS can add and remove filesystem during runtime, but it has to be done via syscalls. The SETUP program does the necessary syscalls to mount the beginning of the first hard disk to the C drive. Then it detects the geometry of the hard drive and calls FORMAT with the correct arguments.

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