+-------\/-------+ | | A7-+ +-VCC | | A6-+ +-A8 | | A5-+ 4026-0001 +-A9 | | A4-+ +-REX | AG-035A-11 | A3-+ +-A12 | | A2-+ +-A10 | (c)83 ACTVSN | A1-+ +-EN_OUT | | A0-+ +-D7 | | D0-+ +-D6 | | D1-+ +-D5 | | D2-+ +-D4 | | GND-+ +-D3 | | +----------------+ Activision's 'Custom Sound Chip'. Hooks up to busses as indicated; REX goes through a 680K resistor to +5V. Placing a finger across this resistor changes the tone of the music! EN_OUT goes to the enable input of the ROM. Note that A11 isn't used by this chip. EN is positive-going +-------\/-------+ | | EN_OUT+ +-GND | | A12-+ +-A6 | | A7-+ CO20231-11 +-D7 | | A8-+ +-D6 | | A9-+ +-D5 | | A10-+ +-D4 | | A11-+ +-A5 | | A3-+ +-D3 | | A2-+ +-D2 | | A1-+ +-D1 | | A0-+ +-D0 | | VCC-+ +-A4 | | +----------------+ This is Atari's 'Super Chip'. Note the weird pinout. Also, power and ground are reversed! EN_OUT goes to the enable input of the ROM. This chip interfaces suspiciously like the one above. The enable output is positive-going. +-------\/-------+ | | A7-+ +-VCC | | A6-+ +-A8 | | A5-+ +-A9 | | A4-+ Standard +-VCC (Another Enable or address line?) | | A3-+ +-A12 (enable) | ROM | A2-+ +-A10 | | A1-+ +-A11 | | A0-+ +-D7 | | D0-+ +-D6 | | D1-+ +-D5 | | D2-+ +-D4 | | GND-+ +-D3 | | +----------------+ *Everyone* uses this pinout. Activision and Atari use this pinout for their ROMs. PB however, uses a slightly diffrent pinout. +-----\/-----+ | | F6/F8-| |-VCC | | A13 ON EPROM-| |-VCC | GA035 | A12 ON EPROM-| |-A5 | | A0-| |-A1 | | A2-| |-A3 | | A6-| |-A4 | | A8-| |-A9 | | A11-| |-/CE ON EPROM | | A7-| |-A12 | | GND-| |-A10 | | +------------+ This is Activision's bankswitch chip. I found it on a Double Dragon cart. It performs an F6 bankswitch, and I believe it'll do an F8 as well; pin 1 had a solderable jumper on it; it's open for F6, and shorted to A3 for F8. This would make sense, because A3 is low for 1FF6 and 1FF7, while it's high for 1FF8 and 1FF9. More accurately it's a positive enable. :-) That just leaves the question about what pin 19 does. Also in the cart was a 27C128 EPROM that contained the actual game code. (16K)