You are right, the code is designed to work with redirected input, con works fine, I should have been more clear. Int 21h 01h is not a console function, it is an input function and it should work with redirected input. I imagine you are right, no games need this functionality at least from redirect. …

Int 21h function 01h does not echo input characters to the console. I built the attached TASM code using Turbo Assembler 5.0 under DOSBox 0.72 on these machines: Dell D630, Windows XP 64 bit, sp3, 4GB RAM, Quadro NVS 135 128MB. Dell Precision 490, Dual Xeon Dual-Core 3.2, 24GB RAM, Vista 64-bit Dell …