It's 1987. I'd just spent a few months building a small single-floppy bootable OS for the IBM PC. The purpose of this project was to display a small training demonstration for security-related personnel in a protected environment. There were to be no ways to interrupt/interfere with the system running the training program, and it absolutely could not have been done in DOS or CP/M - had to be its own standalone system, 100%. It had absolutely to be something that 'could not be copied in a normal computer', where normal was: any of the DOS-booting machines out there in the final location.
So we built a boot-loader, a small kernel, packed the training-material resources into a tiny VM, wrote a VM to process the bytecode and run the training app, and delivered two bootable - albeit 'uncopyable' - floppies with the app - one for the demo, and one for the final installation. The app worked great, but building the floppy required a fair bit of magic hand-waving, back in those days. I retired after giving the delivery-person their two, very valuable floppies, with only thoughts on my mind that perhaps one day I should automate all that sector-placing hand-waving magic ..
So, I get a call from the remote location at 4am in the morning, saying that the demo floppy had been placed on top of some magnetic thing accidentally, the person had been fired, and how do we make another copy of the floppy for the install at 7am?
Well, indeed. "We'll have to do a sector-copy. Do any of your DOS machines have debug.com installed, by any chance .." A 7-line assembly routine to do block copies, 15 minutes of waiting-on-hold listening to remote floppy copy noises later, and we had our copy. The scant few hours I had in between dreaming of the routine, and then actually having to explain to a non-technical person over the phone how to assemble it into a working program in a way that won't destroy the only working copy .. well, lets just say I learned a lot of things in that project that I'm still trying to un-learn. ;)
So we built a boot-loader, a small kernel, packed the training-material resources into a tiny VM, wrote a VM to process the bytecode and run the training app, and delivered two bootable - albeit 'uncopyable' - floppies with the app - one for the demo, and one for the final installation. The app worked great, but building the floppy required a fair bit of magic hand-waving, back in those days. I retired after giving the delivery-person their two, very valuable floppies, with only thoughts on my mind that perhaps one day I should automate all that sector-placing hand-waving magic ..
So, I get a call from the remote location at 4am in the morning, saying that the demo floppy had been placed on top of some magnetic thing accidentally, the person had been fired, and how do we make another copy of the floppy for the install at 7am?
Well, indeed. "We'll have to do a sector-copy. Do any of your DOS machines have debug.com installed, by any chance .." A 7-line assembly routine to do block copies, 15 minutes of waiting-on-hold listening to remote floppy copy noises later, and we had our copy. The scant few hours I had in between dreaming of the routine, and then actually having to explain to a non-technical person over the phone how to assemble it into a working program in a way that won't destroy the only working copy .. well, lets just say I learned a lot of things in that project that I'm still trying to un-learn. ;)