GT Racing is yet another Mode 7 racer for the SNES, this one featuring a variety of licensed real-world cars to choose from.
It also has an unusually elaborate debugger and a couple of intriguing easter eggs.
SFC Delux Monitor
GT Racing (along with Olivia's Mystery and Touge Densetsu: Saisoku Battle) contains a fully working machine code monitor (or, in other words, a text-based debugger) usable via a 9600 baud serial connection between the Super Famicom and a terminal. Such tools were widely available for home computers in the 80s, but essentially unheard of on consoles. This particular monitor has the ability to view and modify memory, disassemble code, transfer memory to the terminal via the XMODEM protocol, and set execution breakpoints on code.
|Download GT Racing monitor patch
File: SFCDeluxMonitor.rar (15kb) (info)
Current version: 1
The above download consists of a small assembly hack and a Lua script which allows the monitor to be accessed using this version of snes9x-rr and a terminal emulator. Apply the IPS patch to an unheadered ROM, then put the other files in the same directory as snes9x-rr and load the "test.lua" script in the emulator.
Once the script is running, use your terminal emulator of choice to connect to localhost on port 8420 (for best results, make sure local echo is disabled and use Shift-JIS text encoding). Load the ROM and keep the Select button held down to boot into the monitor, and you should see the "SFC DELUX MONITOR" prompt in your terminal.
From here, you can enter any of the following commands:
- R - view register status
- B [val] - change / view data bank
- RB val - change program bank
- RPC, RA, RX, RY, RP, RS val - change other registers
- @, G, T, U - resume execution w/ current register values
- D [addr] - dump current program bank (addr defaults to PC)
- VD, SD [addr] - dump VRAM / ARAM (addr defaults to $0000)
- L [addr] - disassemble current program bank (addr defaults to $0000)
- M addr - edit current data bank
- 1MROM, 4MROM, DLS, DLV, DLB - download ROM, ARAM, or VRAM via XMODEM (press B when prompted to initiate transfer)
- BP [addr] - set/view breakpoints in current data bank
- BC num - clear breakpoints
- MONI - reset registers/breakpoints
- LOCK - unknown
- EXIT, GAME, Q, QUIT, RUN, SYSTEM - exit monitor
- HELP, ? - old command help (most commands missing, some help text inaccurate)
- RESET - restart monitor (broken)
Breakpoints most likely require the ability to write to the cartridge in order to work, and thus aren't actually usable this way (but if you're doing this, you most likely have access to a SNES emulator with richer debugging capabilities anyway).
"Ln-MOS version 3.1"
In addition to the above, the game also has a bit of unreachable code to display a fake DOS-like boot sequence, which imitates a computer's self test and then prints a fictitious directory listing, consisting mostly of the same few file names repeated several times, before going into an infinite loop. The same code can also be found in Gunman's Proof and Touge Densetsu: Saisoku Battle.
The display is surprisingly polished for what seems to be no more than a strange disabled Easter egg, even including a simulated CRT-esque "rolling line" effect in the background. The significance, if any, of the file names and (obviously bogus) dates is unknown, as the entire output is hardcoded and does not correspond to any actual contents of the game's ROM.
codes to view it in this game; the Gunman's Proof article has working codes already
"Ir-GOS version 6.3"
Finally, another very similar screen (with a different name and crediting Imagineer instead of Lenar) is also present. Unlike the Ln-MOS screen, this appears to be referenced in two places in the game's code.
add PAR codes and find out possible other ways to access
Where the previous screen displays a fake file listing and then goes into an infinite loop, this one displays a much shorter listing and then "runs" one of the files, which causes the game's credits sequence to be displayed. Also unlike the other screen, this one uses sound effects to further simulate booting up and typing on a computer.
This easter egg does not appear in any other games.