cartridge version WIP. Not really usable yet.

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+
+What's needed to get taipan onto a cart:
+
+joey_z is willing to manufacture carts like this:
+
++---------------------------------------------------------------------------+
+| Type 13: XEGS 64 KB cartridge (banks 0-7)                                 |
++---------------------------------------------------------------------------+
+
+ One of the two variants of the 64 KB XEGS cartridge, that's built on either
+ a C100649 board with the W1 solder point not connected, or a C026449 board
+ with pin 9 of the 74LS374 chip unconnected.
+ This bank-switched cartridge occupies 16 KB of address space between $8000
+ and $BFFF. The cartridge memory is divided into 8 banks, 8 KB each.
+ Bank 7 (the last one) is always mapped to $A000-$BFFF. Three lowest bits of
+ a byte written to $D500-$D5FF select the bank mapped to $8000-$9FFF.
+ The initially selected bank is random, although it seems that 0 gets chosen
+ the most often. Atari800 always selects bank 0 initially.
+
+ Reference:
+ http://www.atarimax.com/jindroush.atari.org/acarts.html#xegs
+
+"For bank-switched cartridges banks are numbered in the order they appear
+in the image file, starting with 0."
+
+...so:
+
+Bank 7 will have the startup code, uncompressed title screen, title
+code, and code to copy from the other banks to RAM.
+
+That gives me banks 0-6 to store code in. The code is 27174 bytes, so I
+have plenty of space: it'll occupy 4 banks, leaving 2 empty ones. The
+last code bank will only be 1/3 full of code... but 1K of it will be
+used for the font, so 4.5K free there.
+
+Code in bank 7 will copy all the chunks to correct place in RAM... and
+I don't need to leave room for DOS or anything else, so the code can be
+ORGed at $0400 (romable_taimain.raw target in the Makefile does this).
+
+$0400 + 27174 means the code ends at $6e26, and the BSS is less than a
+page. The OS will place the GR.0 display list at $7c20, and the stack
+will grow down from there to $7a40 (except it never grows that much).
+
+Copying the code to RAM will take some time, but not too much. Should be
+around 1/4 second, don't need a progress bar or anything. Not sure when to do
+the copying:
+
+1. At boot, before displaying title screen?
+2. After the title screen is displayed, before the menu is active?
+3. After the player presses space/enter to start the game?
+
+Options 1 and 3 will allow turning off ANTIC DMA during the copy, making
+it a bit faster. Option 2 gives the player something to look at while
+the copy is happening, but I think it'll be so quick as to not matter.
+
+Amusingly, the Taipan cart will work on a 32K 800. Not a 16K Atari though.
+
+bank 7: fixed bank
+$a000-$b9xx - title screen data, dl, menu code
+$ba00-$bff9 - memory checker plus code to copy romable_taimain to RAM
+$bffa-$bfff - cart trailer
+
+banks 0, 1, 2: full banks of romable_taimain code
+$8000-$9dff - 30 pages (7680 bytes) of code
+$9f00-$9fff - unused
+
+bank 3: last (partial) bank of romable_taimain, plus the font
+$8000-$9bff - up to 7K of code (28 pages)
+$9c00-$9fff - font (1K)
+
+Unused areas are filled with $ff. For the banks that map at $8000, this
+includes the cart trailer area. A non-zero byte (our $ff) at $9ffc tells
+the OS that a cart isn't inserted in the right slot, so it won't try to
+initialize/run our cart as a right cart. Only bank 7 (that maps as a
+left cart) needs a valid cart trailer... according to cart.txt, every
+once in a while, bank 7 might come up selected at power on. This shouldn't
+matter: it'll be in both bank areas, and if the OS tries to init it as
+a right cart, the init/run addresses will point to the left cart area.
+
+banks 4, 5, 6 are unused (24K total). Possibly the manual goes here,
+if I write one.
+
+--
+
+Changes the game will need for a cart version: Not many.
+
+checkmem.s won't be needed any longer... though there will need to be
+a new memory checker (in bank 7) that says "32K required" if someone
+tries it on a 16K machine.
+
+"Play again?" should probably be "Press any key to play again" since
+there's no place to exit() to. Unless I do a manual! Then it'll exit
+to the title screen, from whence the user can choose the manual or else
+start the game again.
+
+The title decompression will be gone: it'll just display the title screen
+DL and data straight from ROM. The menu help text might be in RAM though,
+as at least 2 bytes need to be modified (sound on/off).
+
+The font will be located in ROM, on a 1K boundary, so CHBAS can point
+to it (no need to copy to RAM).
+
+num_buf and firm will be located in the BSS rather than page 6 as they
+are in the .xex version.
+
+Since I have 3 empty banks... Why not include a manual on the cart,
+with pseudo-hypertext UI?
+
+--
+
+Cart header (trailer, actually). Can I get away with using the same one
+for all banks? IIRC, the low one ("right cartridge") gets looked at first,
+does that mean the high bank doesn't even need a header?
+
+atari800 can load a .xex that's built with --start-addr 0x400. This will
+make testing the cart stuff slightly easier.
+
+--
+
+What would be *really* slick: figure out a way to split the code up
+across banks and include bankswitching in the logic, so it runs from
+the cart and switches banks as needed. This would allow Taipan to run
+on a 16K or even an 8K 400/800!
+
+Can it be done? Surely. Can it be done without rewriting everything
+in asm? Probably. Do I want to? Not really.
+
+--
+
+The cartridge label should look like a classic brown 1st-gen 400/800 cart.
+Yellow text:
+
+TAIPAN!
+Computer Game
+
+and a bogus serial number.. CXU000001 or such (U for Urchlay).
+
+The top should say LEFT CARTRIDGE.
+
+If there's going to be a printed manual, it should be based on the Apple II
+version's manual. If there was one. If I can find a copy.