Pinout of EXT BUS and HuCARDs:
------------------------------

Notes:
	*  - means I think this is what it is
	** - means I don't know
	It's a rear view.

RA   Gnd Hu  **  A17 A13 A11 Gnd D2  D4  D6  D7  A1  A3  A4  A6  Gnd A15 A18 Gnd +5v **  **
A20* CD  35  R/W **  A8  /OE D0  D3  D5  **  A0  A2  **  A5  A7  A12 A16 /CE **  37  36  **
LA   +5v **  A19 A14 A9  A10 D1  **  **  Vin **  **  Vin **  **  **  **  **  **  Gnd **  **
 
Explanation of the codes: 

	##  -- HuCard pin that i don't know what it is.
	RA  -- Right Audio
	LA  -- Left Audio
	+5  -- +5V, regulated
	Gnd -- ground
	CD  -- CD 'sense' line.		CD:  shorted to ground
	Vin -- External voltage input.	CD:  supplies +5V
	Hu  -- "HuCard detect" - when grounded, this shows that a
		HuCard is inserted (all proper HuCards have pins 1
		and 18 connected). (Thanxx for this info Dave)

Pin 1 is the short pin (on the left, if the card is to
inserted forwards), pin 38 is the long pin on the right.

Pin	Use
---	---
1	Hu				20	D4
2	A20*				21	D5
3	A19				22	D6
4	A16				23	D7
5	A15				24	/CE - chip select
6	A12				25	A10
7	A7				26	/OE - output enable
8	A6				27	A11
9	A5				28	A9
10	A4				29	A8
11	A3				30	A13
12	A2				31	A14
13	A1				32	A17
14	A0				33	A18
15	D0				34	R/W - read/write
16	D1				35	**
17	D2				36	**
18	Gnd				37	**
19	D3				38	+5V

Info compiled from various sources by Yoann Michot aka Vlendr'it
vlendrit@club-internet.fr