$Id: md_pinouts.txt 962 2014-09-22 23:46:56Z notaz $

       Cart                     Exp               Cart (SMS mode)
(face) <-->  (back)      (back) <-->  (face)     (face) <-->  (back)
SL1    B01A  GND          GND   A01B  GND        ?      B01A  GND
/MRES  B02A  Vcc1         VA19* A02B  /DISK (?)  ?      B02A  Vcc1
SR1    B03A  VA 8         /CAS0 A03B  VA 1       ?      B03A  A7
VA 9   B04A  VA11         VD 0  A04B  VA 2       A8     B04A  A10
VA10   B05A  VA 7         VD 1  A05B  VA 3       A9     B05A  A6
VA18   B06A  VA12         VD 2  A06B  VA 4       /CE    B06A  A11
VA19   B07A  VA 6         VD 3  A07B  VA 5       ?      B07A  A5
VA20   B08A  VA13         VD 4  A08B  VA 6       ?      B08A  A12
VA21   B09A  VA 5         VD 5  A09B  VA 7       (plup) B09A  A4
VA22   B10A  VA14         VD 6  A10B  VA 8       (pldn) B10A  A13
VA23   B11A  VA 4         VD 7  A11B  VA 9       /NMI   B11A  A3
/YS    B12A  VA15         GND   A12B  GND        ?      B12A  A14
/VSYNC B13A  VA 3         VD 8  A13B  VA10       ?      B13A  A2
/HSYNC B14A  VA16         VD 9  A14B  VA11       ?      B14A  ?
EDCLK  B15A  VA 2         VD10  A15B  VA12       ?      B15A  A1
/CAS0  B16A  VA17         VD11  A16B  VA13       /Rd    B16A  ?
/CE0   B17A  VA 1         VD12  A17B  VA14       /M0-7  B17A  A0
/AS    B18A  GND          VD13  A18B  VA15       ?      B18A  GND
VCLK   B19A  VD 7         VD14  A19B  VA16       ?      B19A  D7
/DTAK  B20A  VD 0         VD15  A20B  VA17       ?      B20A  D0
/CAS2  B21A  VD 8         /ROM  A21B  /LWR       ??     B21A  ?
VD15   B22A  VD 6         /ASEL A22B  /UWR       ?      B22A  D6
VD14   B23A  VD 1         /RAS2 A23B  /CAS2      ?      B23A  D1
VD13   B24A  VD 9         /FDC  A24B  /FDWR      ?      B24A  ?
VD12   B25A  VD 5         FRES  A25B  VA18*      ?      B25A  D5
/ASEL  B26A  VD 2         Vcc1  A26B  Vcc1       ?      B26A  D2
/VRES  B27A  VD10         SR3*  A27B  SL3*       ?      B27A  ?
/LWR   B28A  VD 4         +9V   A28B  +9V        /Wr    B28A  D4
/UWR   B29A  VD 3         SR2   A29B  SL2        ?      B29A  D3
/M3    B30A  VD11         GND   A30B  GND        /M3    B30A  ?
/TIME  B31A  Vcc1                                ?      B31A  Vcc1
/CART  B32A  GND          * - MD2 only           /CART  B32A  GND

GND      - Ground
Vcc1     - Positive supply voltage (+5V)
N.C.     - not connected
VA1-VA23 - Address bus
VD0-VD15 - Data bus
SLx,SLx  - Stereo Left in, x={1,2,3}
/MRES    - / hard (bootup) reset [H_RESET]
SRx,SRx  - Stereo Right in, x={1,2,3}
/YS      - / VDP doing backdrop color [VIDEO]
/VSYNC   - / Vertical Sync
/HSYNC   - / Horizontal Sync
EDCLK    - VDP related clock, changing, Mclk/5 ~ Mclk/4 [HS_CLK]
/CAS0    - / set for reads on $000000-$DFFFFF, acts as /OE signal [C_OE]
/CE0     - / Chip Enable, set for r/w [1] $000000-$3FFFFF or [2] $400000-$7FFFFF [C_CE]
/AS      - / Address Strobe - addr bus valid
VCLK     - 68k clock [CLK]
/DTAK    - / Data Transfer acKnowledge for 68k [DTACK]
/CAS2    - / ?
/ASEL    - / set for r/w $000000-$7FFFFF [LO_MEM]
/VRES    - / reset (from switch) [S_RESET]
/LWR     - / Lower byte WRite [LDSW]
/UWR     - / Upper byte WRite [UDSW]
/M3      - / "mark III" (master system) mode
/TIME    - / set for r/w $A13000-$A130FF
/CART    - / CART inserted
/ROM     - / set for [1] $400000-5FFFFF [2] $000000-$1FFFFF
/RAS2    - / ?
/FDC     - / set for r/w $A12000-$A120FF
FRES     - / ?
/DISK    - / set for r/w $A12000-$A120FF (same as FDC?)
/FDWR    - / set for w $A12000-$A120FF?