The files here are 'production' versions of system code:

bootstrap_tty.asm
    The TTY bootstrap ROM code created from the data in file
    images/imlacdocs/loading.pdf.

blockloader_c8lds_ptr_tty.asm
    The blockloader for c8lds format files found in iasm/chars.ptp.

blockloader_lc16sd_tty.asm
    The blockloader for lc16sd format files found in bin/munch.ptp.