.COM files were straight binary, no header and loaded at address 256 (0x100) into any 64KB segment. All indirections were local to that segment, hence the 64KB

.COM files were straight binary, no header and loaded at address 256 (0x100) into any 64KB segment. All indirections were local to that segment, hence the 64KB limit of .com files. The characters you were typing are (probably) the code for a jump to an entry point somewhere else in the file.