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https://github.com/Pecusx/jataricart.git
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Jakub Husak
42 lines
1.9 KiB
Markdown
42 lines
1.9 KiB
Markdown
# JatariCart
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This software is for use with my super simple flash cartridge (no gals, only 3 74xx elements and some caps and resistors). Top side is that without elements.
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The cartridge is driven by addresses D500-D580; write to D500 sets the first bank - this is default boot bank. Write to D501 sets second bank etc. The max usable number with cart on is set by write to D51F; write to D580 switches off the cartridge.
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The internal construction of JatariCart allows utilise max 256kB of flash memory (32 banks) or of course PROM/EPROM memory.
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The memory package is plcc32.
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Flash memory can be programmed/flashed from Atari platform by flasher application, wchich you can find in "flashwriteexample" catalog.
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The flasher must be (for now) preassembled using mads assembler with proper rom file included bank by bank (the flasher source does it by itself).
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If you want to write your own cartridge access, remember to fool the Operating System not to hang up by cart on/off, by:
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<pre>
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carton (x - bank to switch)
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pha
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sei
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sta $D500,x
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sta wsync ; needed for ntsc, no big difference in speed
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sta wsync ; needed for ntsc
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lda trig3
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sta gintlk
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cli
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pla
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rts
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</pre>
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after each access. This will let the system think as cartridge never was switched/removed/inserted. Of course it is better (much better, obligue) that there is no display list, video memory and no interrupts in the area a000-bfff, which can be anything when bank swapping.
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Files and descriptions:
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flashwritelib.asx - 6502 code library for formatting flash/formatting sector and write byte.
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flashsrite.asx - 6502 code for generate flasher (when compiled, it contains either flash routines and cartridge image itself)
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crc16_v2.asm - crc16 library for fast checking every sector (when flash is damaged, sometimes it happens that write sector damages another)
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Compile (mads needed, http://mads.atari8.info):
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mads flashwrite.asx -o:flashwrite.xex
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