Expand description
The runtime’s one remaining BIOS entry point: TTY putchar.
Normal operation talks straight to the hardware; the i-cache flush
that used to go through A(44h) FlushCache is now
crate::cache::flush_instruction_cache. The single service still routed
through the BIOS dispatch convention is A(3Ch) putchar, kept
because it is the canonical PS1 debug channel: the emulator’s HLE
prints it to the host terminal, and on a real console the BIOS TTY
device swallows it harmlessly. It is reached only from panic
reporting and debug prints (crate::tty), never from a frame
loop.
The trampoline is a 3-instruction stub against the publicly
documented A-table dispatch convention: load the table address into
$t0, jump to it, put the function index into $t1 in the branch
delay slot.
Functions§
- write_
char - Write one byte to TTY via BIOS
putchar.