Sun 2018-09-09 19:58:13 -0400
I’ve been having a blast with DOS 2.10. Actually it’s PC-DOS 2.10, the IBM version. I built a simple DOS VM on VirtualBox on my Mac, found and downloaded PC-DOS install floppy images, maybe there was just one floppy, and booted up the computer from the floppy.
Installing was pretty easy after using FDISK to format the hard drive and copying the files over. I copied a few lines in to create AUTOEXEC.BAT and CONFIG.SYS files and was then able to boot from the C drive.
I configured the VM with 640 KB of RAM and about a 20-MB hard drive.
There are no multi user accounts, no networking so no configuration there, no multi processing with services running. Just files on a disk that you can run.
On an Ubuntu system I made some floppy images and copied some of my old DOS BASIC and TurboPascal programs onto them.
dd if=/dev/zero of=mydisk.img bs=1024 count=360
Then created a FAT file system on them.
mkfs -t msdos mydisk.img
After copying the old files onto them (which were stilled organized into disks by directories), I copied the disks over to the Mac with the VM, attached each floppy one at a time, and copied its files over.
The OS doesn’t see the clock on the VM, maybe there’s something I need to do there to fix that, so I have to type in the date each time it boots.
The BASIC and BASICA programming environments don’t work which I’m sure is because they required code that was included in ROM on the original IBM PC. However, one of my disks had a copy of GW-BASIC on it which was entirely self-contained, so it runs fine.
I found and downloaded a copy of TurboPascal version 3 and also discovered I had the original files copied from one of my floppies. At first I was a little disturbed that I seemed not to be able to read some of the Pascal code I looked at. When I read my own code, though, I had no trouble. I claim that I was writing pretty readable code even back then.