GBA工程源程序，开发学习GBA的好东东。

Nocash Multiboot/Burstboot Uploader (c) 2001,2002 Martin Korth This is the standalone DOS version of the multiboot upload program, which is also being built-in into the no$gba debuggers utility menu. Contents -------- 1) AUX Multiboot PC-to-GBA Cable 2) Extended Multiboot Header 3) Burst Boot Backdoor 4) Downloading the GBA BIOS I hope this will be easy to use. I've spent about three weeks (fulltime) into trying to get it as fast and comfortable as possible, and by using as little hardware as possible... http://www.work.de/nocash/ Many thanks to arundel for testing dozens of beta versions on 100MHz, 350MHz, and 700MHz computers until the code worked with fast CPUs, and without external pull-up resistors. 1) AUX Multiboot PC-to-GBA Cable -------------------------------- Below describes how to connect a PC parallel port to the GBA link port, allowing to upload small programs (max 256 KBytes) from no$gba's Utility menu (or by using the standalone DOS version) into real GBAs. This is possible because the GBA BIOS includes a built-in function for downloading & executing program code even when no cartridge is inserted. The program is loaded to 2000000h and up in GBA memory, and must contain cartridge header information (nintendo logo, checksum, etc) just as for normal ROM cartridges. Basic Cable Connection The general connection is very simple (only needs four wires), the only problem is that you need a special GBA plug or otherwise need to solder wires directly to the GBA mainboard (see Examples below). GBA Name Color SUBD CNTR Name 2 SO Red ------------- 10 10 /ACK 3 SI Orange ------------- 14 14 /AUTOLF 5 SC Green ------------- 1 1 /STROBE 6 GND Blue ------------- 19 19 GND Optionally, also connect the following signals (see notes below): 4 SD Brown ------------- 17 36 /SELECT (double speed burst) - - - +----------- 2..9 2..9 D0..7 (pull-up) - - - |---[===]--- 14 14 /AUTOLF (pull-up) - - - |---[===]--- 1 1 /STROBE (pull-up) - - - +---[===]--- 17 36 /SELECT (pull-up) RESET (mainboard) ------|>|---- 16 31 /INIT (automatic reset) Notes: The GBA Pins are arranged from left to right as 2,4,6 in upper row, and 1,3,5 in lower row; outside view of GBA socket; flat side of socket upside. The above "Colors" are as used in most or all standard Nintendo link cables, note that Red/Orange will be exchanged at one end in cables with crossed SO/SI lines. At the PC side, use the SUBD pin numbers when connecting to a 25-pin SUBD plug, or CNTR pin numbers for 36-pin Centronics plug. Optional SD Connection (Double Speed Burst) The SD line is used for Double Speed Burst transfers only, in case that you are using a gameboy link plug for the connection, and if that plug does not have a SD-pin (as such from older 8bit gameboy cables), then you may leave out this connection. Burst Boot will then only work half as fast though. Optional Pull-Ups (Improves Low-to-High Transition Speed) If your parallel port works only with medium or slow delay settings, try to connect 570 Ohm resistors to each of the strobe/autolf/select outputs, and the other resistor pin to any or all of the parallel port pin 2..9 data lines (xboo outputs high to all data lines). Optional Reset Connection The Reset connection allows to reset & upload data even if a program in the GBA has locked up (or if you've loaded a program that does not support nocash burst boot). - Without reset connection you'd then manually have to reset the GBA by switching it off and on. The RESET signal is labeled as such on the GBA mainboard. The diode (1N4148 or similiar) is required because otherwise strong INIT signals would pull-up the RESET signal, preventing the GBA from automatically resetting itself when switched on. Optional Power Supply Connection Also, you may want to connect the power supply to parallel port data lines. Different parallel ports output different voltages/amperes though, maybe using a large Z-diode could be used to get a stable voltage with most ports. Even with strong ports, it'll probably not work when inserting a very power-hungry cartridge into the GBA. Transmission Speed The first transfer will be very slow, and the GBA BIOS will display the boot logo for at least 4 seconds, even if the transfer has completed in less time. Once when you have uploaded a program with burst boot backdoor, further transfers will be ways faster. The table below shows transfer times for 0KByte - 256KByte files: Boot Mode_____Delay 0_______Delay 1_______Delay 2_____ Double Burst 0.1s - 1.8s 0.1s - 3.7s 0.1s - 5.3s Single Burst 0.1s - 3.6s 0.1s - 7.1s 0.1s - 10.6s Normal Bios 4.0s - 9.0s 4.0s - 12.7s 4.0s - 16.3s All timings measured on a 66MHz computer, best possible transmission speed should be 150KBytes/second. Timings might slightly vary depending on the CPU speed and/or operating system. Synchronization is done by I/O waitstates, that should work even on faster computers. Non-zero delays are eventually required for cables without pull-ups. Requirements Beside for the cable and plugs, no special requirements. The cable should work with all parallel ports, including old-fashined uni-directional printer ports, as well as modern bi-directional EPP ports. Transfer timings should work stable regardless of the PCs CPU speed (see above though), and regardless of multitasking interruptions. Both no$gba and the actual transmission procedure are using some 32bit code, so that either one currently requires 80386SX CPUs or above. Windows NT/2000/etc. NT/2000/etc. prevent to access parallel ports directly, this problem can be reportedly healed by using special drivers (such like giveio, totalio, or userport), which would be possibly required to be called from inside of no$gba. If anybody can supply information on where to download & how to use these drivers, please let me know! Note: Windows 95/98/etc. are working fine without such drivers, also, the DOS version of the uploader might work okay even under NT/2000. Connection Examples As far as I can imagine, there are four possible methods how to connect the cable to the GBA. The first two methods don't require to open the GBA, and the other methods also allow to connect optional power supply and reset signal. 1) Connect it to the GBA link port. Advantage: No need to open/modify the GBA. Disadvantage: You need a special plug, (typically gained by removing it from a gameboy link cable). 2) Solder the cable directly to the GBA link port pins. Advantages: No plug required & no need to open the GBA. Disadvantages: You can't remove the cable, and the link port becomes unusable. 3) Solder the cable directly to the GBA mainboard. Advantage: No plug required at the GBA side. Disadvantage: You'll always have a cable leaping out of the GBA even when not using it, unless you put a small standard plug between GBA and cable. 4) Install a Centronics socket in the GBA (between power switch and headphone socket). Advantage: You can use a standard printer cable. Disadvantages: You need to cut a big hole into the GBAs battery box (which cannot be used anymore), the big cable might be a bit uncomfortable when holding the GBA. Personally, I've decided to use the lastmost method as I don't like ending up with hundreds of special cables for different purposes, and asides, it's been fun to damage the GAB as much as possible. Note The above used PC parallel port signals are typically using 5V=HIGH while GBA link ports deal with 3V=HIGH. From my experiences, the different voltages do not cause communication problems (and do not damage the GBA and/or PC hardware), and after all real me