DOS 01h Read character behavior on EOF

Question

Using 01h interrupt (AH = 01h - READ CHARACTER FROM STANDARD INPUT, WITH ECHO), what will be output at the end of stdin for a cat program? Is ^Z (1Ah) used to mark the end of stdin by convention?

Testing this program with emu2 (emu2 doscat.com < input.txt) results in FFh being constantly printed, although that might be from emu2 being a C program and reading EOFs as -1.

section .text
start:
        mov ah, 01h ; read char from stdin with echo
        int 21h     ; call DOS services
        jmp start