You are describing MS-DOS. As article states, this used DRI's Concurrent DOS, which was basically rebranded MP/M-86 with a basic MS-DOS compatibility layer. Mo

You are describing MS-DOS. As article states, this used DRI's Concurrent DOS, which was basically rebranded MP/M-86 with a basic MS-DOS compatibility layer. More about Concurrent DOS, eg here: https://nemanjatrifunovic.substack.com/i/196574463/quest-for-concurrency https://nemanjatrifunovic.substack.com/i/196574463/quest-for...