Cartridge slot description
Left slot pinout (all models)
Right slot pinout (only 800)
Parts are (always?) at back (XL)/bottom (XE) part of the cartridge. Connector orientation is S-A from front, 1-15 from back.
Cartridge basicsThere are three different 'windows' or banks in the memory:
Bank $A000-$BFFF is selected by low state on S5. Its presence is signaled by high state on RD5. This signal is attached to TRIG3 in XL/XE series. Used in left carts only.
Bank $8000-$9FFF is selected by low state on S4. Its presence is signaled by high state on RD4. Used in both left and right slot carts.
'Bank' $D500-$D5FF is selected by low state on CCTL. It's used for bankswitching. (mapping ports etc.)
Czech speciality (AFAIK) are cartridges with buttons. There are two different
Romox released 'blank' 16KB cartridges which could be programmed in special
machines. They were called Edge Connector Programmable Cartridges. List of
potential releases is here.
OSS cartsBanks: Usually contain 4 4KB banks. One of the banks is mapped in $B000-$BFFF. Other banks are mapped to $A000-$AFFF.
Detailed article is here.
Double eprom PCB (OSS DBL):
Older scheme, uses 74LS175 (4bit register???), 2 eproms and uses 4 bits of address bus.
Physical order of banks: ROM A = 3, M; ROM B = 0, 4
A0 if 1, selects AL
Single rom PCB (OSS SNG):
Newer scheme, uses 2 d-flipflops, bits A0 and A3.
Physical order of banks: M, 0, 9, 1.
Schematics (8 KB GIF) drawn by me from the board pictures above. I doubt they are 100% correct, but are good enough to understand how does it work.
SDX cartsBanks: Contain 8 8KB banks. Access to base+0-7 turns on banks 0-7 in $A000-$BFFF area. Access to base+8-F turns the cart off.
SDX: Base is $D5E0.
Better said: Cartridge looks for low CCTL and match in A4-A7. For SDX it is 0xE (1110), Diamond 0xD (1101), Express 0x7 (0111). If A3 is high, cart is turned off. If A3 is low, the bank whose number is in A0-A2 is selected. I'm not sure what happens when turning cart off, but I think that it turns off RD5 only.
R-Time 8Pass thru cartridge with battery-backup for real-time clock.
PCB Bottom (109 KB JPG)
PCB Top (113 KB JPG)
Emulated: Atari800 - read only is enough.
XEGS cartsBanks: Contain n 8KB banks. Bank n-1 is mapped at $A000-$BFFF. Banks 0 to n-1 are mapped to $8000-$9FFF by writing the number of bank to any of $D500 registers.
Thanks to Torsten Schall, following are pictures of something called
1MB ROM EMULATOR. It was probably used for developing of XEGS games.
XEGS demo cartridgeBanks:
XEGS 64 - Flight Simulator 2 (shortened version)
XEGS 32 - One on One (same version as on XEGS cart)
LS16 - Joust (same version as on cart)
LS16 - Ms. Pacman (same version as on cart)
Does change game on each reboot (binary counter powered by capacitors).
Telelink 2 cartridgeBanks: Just one 8kb bank at A000-BFFF. Additional hardware is one X2212 nonvolatile SRAM, containing 256 x 4 bits, for storing telephone numbers. It's accessed by reading/writing 9000-90FF. There is also read access to $D501 and write access to $D502, don't know yet for what, but probably for setting read/write mode of the SRAM. The cartridge uses RD4 hardwired to +5V, what means that it takes full 16KB of address space. Not very elegant solution.
MD-DOS cartridgeBanks: Same as OSS SNG cartridges. Uses two additional bits (A5,A4) for selecting 'subcart'. It thus has 4x16KB = 64KB. Also has button, don't know for what it is used (probably for calling the cartridge).
Emulated: My experimental Atari800 emulator - but with possible bugs.
JRC cartridgesToolbox III: Contains 64KB bankswitched cart with reset button.
Rambox2: EPROM part same or very similar to Toolbox III. Additionally contains 256KB of RAM. This ram could be accessed by TT-Dos and BeWe Dos.
EPROM part: 8x8KB banks. Selected by D6, D5 & D4. Bank number is remembered when A7 is off (D500-D57F). If D7 is on, cartridge is off. If button is pressed, register is cleared, RD5 is on, main bank selected.
ram bank select: X = 00 - 7F (7bits) A = A | $F0 (4bits) STA $D500,X Together it's 11 bits of bank address. You can address $80 bytes of memory in region $D580 (7bits). 11 bits + 7 bits = 18 bits = 256KB of RAM. memory write: LDA (BUFRLO), Y STA $D580, Y memory read: LDA $D580, Y STA (BUFRLO), Y Y = 00 - 7F. Uses previously set bank address.
Emulated: My experimental Atari800 emulator.
ATRAX cartridgeBanks: Contains 16 x 8KB banks (128KB). Uses A000-BFFF region. Bits 0-3 select bank. Bit 7 turns cart off. Menu program loads standard Atari dos executable, then turns cart off. I was told that 16 different carts exists.
Bounty Bob cartridgeBanks: Very strange bankswitching method. Contains main bank at A000-BFFF. From 8000-8FFF is first bank, 9000-9FFF is second bank. They are switched by accessing 8FF6-8FF9 (9FF6-9FF9). In each bank there's 4 x 4 KBs. Totally, it's 2 x 4 x 4 + 8 = 40 KBs. I was told that the cartridge is almost same as 5200 version and such cart contains only three chips: one 8KB rom, and two special self-switching 16KB roms. What circuitry is inside those chips is unknown to me.
128/256 K RamCartBanks: Unknown.
A/D ConverterBanks: None. Uses lower four bits of $D500 for getting the digitized sound from mono analog input.
Super ChargerBanks: Nothing than a multiply/divide chip inside to speed up 3d graphics calculations. Chip type is unknown. Used together with game disk 'Assault Force'.
Emulated: My experimental Atari800 emulator.
Banks: None. Just a way to fool the computer into thinking that cartridge is inserted.
Willams multibanked cartridgeBanks: Contains 8 x 8kb banks. Writing to $D500 turns on first bank (on bootup), writing to $D507 turns on last bank. Writing to $D508 turns cart off. Video61 uses this design for their newly released 'big' cartridges.
Emulated: Atari800 (from >1.2.2)
Thompson ProburnerEPROM burner.
Banks: Contains 8kb in right slot, accesses D500, probably hardware for chip writing. Need more info.
Banks: 16kb main bank. The other is banked in for a short period of time (would anybody compute that for me?) by any access to $D5xx area. Also contains the button on RD4/RD5. As I have other similar COS cartridge, I seem to remember the was some kind of service/toolkit which allowed to put anything on the cart.
Schematics (25 KB GIF)
Great source of information about memory and cartridge mappings is in the article by John Picken. Back (c) 1998-2004 Jindroush Last modified: Tue Mar 25 12:38:31 2003