HuCard pinout

Pinout
Card | | PC Engine -+--+--   1 |->| /CD 2 |->| AUDIO IN   3 |<-| CPU PA19 4 |<-| CPU PA16 5 |<-| CPU PA15 6 |<-| CPU PA12 7 |<-| CPU PA7 8 |<-| CPU PA6 9 |<-| CPU PA5 10 |<-| CPU PA4 11 |<-| CPU PA3 12 |<-| CPU PA2 13 |<-| CPU PA1 14 |<-| CPU PA0 15 |<>| CPU D0 (PCE) or D7 (TG16) 16 |<>| CPU D1 (PCE) or D6 (TG16) 17 |<>| CPU D2 (PCE) or D5 (TG16) 18 |--| GND 19 |<>| CPU D3 (PCE) or D4 (TG16) 20 |<>| CPU D4 (PCE) or D3 (TG16) 21 |<>| CPU D5 (PCE) or D2 (TG16) 22 |<>| CPU D6 (PCE) or D1 (TG16) 23 |<>| CPU D7 (PCE) or D0 (TG16)   Orientation: 24 |<-| CPU PA20                    -- 25 |<-| CPU PA10                    .---. 26 |<-| CPU /RD                     | .-..--| 27 |<-| CPU PA11                    | |         ||      |- 1 28 |<-| CPU PA9                     |>|  Label  ||      | 29 |<-| CPU PA8                     | |         ||      |- 38 30 |<-| CPU PA13                    | '- '' --| 31 |<-| CPU PA14                    '---' 32 |<-| CPU PA17 33 |<-| CPU PA18                    Legend: 34 |<-| CPU /WR                     -- 35 |<-| HSM                         [HuCard]-- Power, n/a 36 |<-| /RST                        [HuCard]<- HuCard input 37 |->| /IRQ2                       [HuCard]-> HuCard output 38 |--| +5V                         [HuCard]<> Bidirectional

Signal descriptions

 * /CD: Card detect. Connects to the expansion port. Grounded by the HuCard so the CD-ROM2 can tell a card is inserted.
 * AUDIO IN: Mono audio. Mixed into both channels.
 * CPU PA20..0: CPU physical address (the 21-bit post-MMU address). PA20 is used as /CE.
 * CPU D7..0: The order of these pins depends on region. For PC Engine, they are ascending, and for TurboGrafx-16, they are descending.
 * HSM: High speed mode, asserted by the CPU when operating at 7.16 MHz.