DOS wasn't designed for multitasking, let alone running multiple TCP/IP applications all at once. The issue is that if you have a packet driver, it uses a single interrupt number (say 0x60). If more than one application tries to intercept that interrupt, both of the applications don't work. If you use a multi-tasking environment on top of DOS, such as Windows 3 or DesqView, whilst you can run multiple apps at the same time, the same problem exists with the interrupt vector. So you're still stuck. In this video, I show you how to run multiple DOS-based TCP/IP applications at the same time. I use DesqView 386 (https://winworldpc.com/product/desqview/2x ) for my example, but it is possible to use Windows 3.0 and 3.1 too. To get it working, I used PKTMUX ( http://cd.textfiles.com/pdos9606/NETWORK/TCPIP/GENERAL/PKTMX12I.ZIP ) and Michael Brutman's mTCP stack (https://www.brutman.com/mTCP/ ). Special acknowledgement goes to Eirik Øverby for his assistance with this challenge. You can find details of his 286 based setup at http://floppy.museum/thispc.htm
00:00 - Start
06:59 - Step 1: Load Packet Driver
07:16 - Step 2: Load Packet Multiplexer
07:26 - Step 3: Update MTCP.CFG to use 0x65
08:33 - Step 4: Start up multitasking environment
09:00 - Step 5: Load a multiplexed packet driver
10:17 - Step 6: Running another TCP application
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