Ex-link in service mode on A series(SH4)

See Getting access to u-boot (SH4) how to connect a Service Cable - ExLink. Provided that you have working Ex-link connection you can enter following commands (based on T-RBYDEUC firmware)

Debug Menu

Let serial line calm down from huge boot messages and type

debug [ Enter ]

Very complex menu tree follows. You can do lot of things there, especially screw up your TV completely.

BE VERY CAREFUL AND ABSOLUTELY SURE YOU KNOW WHAT YOU ARE DOING

Other Debug commands

I doubt about usefulness of following commands:

^ [ Enter ]

CPU reset (TV screen is shifted because GPU is not properly initialized) - same as micom 143.

keydebug [ Enter ]
keyrec [ Enter ]
keyexit [ Enter ]

Repeats periodically sequence of simulated key presses.

Simulated remote control

Enter one character code followed by [ Enter ] to simulate a remote control key press.

Character entered to Ex-link	RC command code (hex)	Command
1 2 3 4 5 6 7 8 9 0	4 5 6 8 9 0xa 0xc 0xd 0xe 0x11	numeric keys
space	0x3b	Factory (not available on standard RC)
`
s
!	0x65	left
#	0x61	down
$	0x62	right
.	0x19
<	0x20
@	0x60	up
D	0x43	?? shows channel number
N	0x32	?? not avail
Z	0x0f	mute
d	0x10	prog-
e	0x68	enter
f	0x44	favorite channel?
g	0x4f	guide
i	0x1f	info
l	0x0b	vol-
m	0x1a	menu
n	0x33	?? not available
p	0x13	prev-ch
r	0x07	vol+
u	0x12	prog+
v	0x01	source
x	0x2d	exit
z	0x25	subt