Thread: Amiga Problems
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Old 05 September 2010, 20:41  
Jope
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Join Date: Jul 2003
Location: Helsinki / Finland
Age: 38
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How to connect an A500 keyboard controller to the rev1 A1200 motherboards.

A500 -> A1200 motherboard
CLK kbd (pin 1) -> pin 44 CIA U7
DAT kbd (pin 2) -> pin 43 CIA U7
RST kbd (pin 3) -> pin 38 keyboard MCU U13
+5 kbd (pin 4) -> anywhere where there's a Vcc pin on the motherboard. I took it from the keyboard MCU pin 4, but you could steal it from the floppy drive power connector or directly from the power supply connector or where-ever.
GND kbd (pin 6) -> same as pin 4, take it from the floppy connector or where-ever. I actually took the GND and LED pins out of the keyboard molex connector and plugged then directly into the motherboard LED header, wrapped some duct tape around them for insulation and rode into the sunset.

If you only get ''''s when you type, then you have CLK and DAT swapped around at U7. Desolder, resolder, try it again.

The following taken from A1200exkb.lha, but with CLK and DAT changed around to reflect real life: (if you only look at that lha and nothing else, it doesn't matter as the signals are swapped consistently in that document. if you cross reference, then it becomes a pain, so I will post them correctly here.)

Code:
A500:				Ribbon out (usually rainbow)
				    Black=1...Purple=8
					||||||||
			+---------------------------------------+
			|	 Pin 1->........<-Pin 8		|
			|		|||| |		     XX<--Shield Gnd.
			| A500          |||| \Gnd		|
			| Keyboard	|||\+5v		   [===]<--Power LED
			| Encoder	||\_KBReset		|
			|		|\KBDat		   [===]<--Drive LED
			| +-----------+	\KBClk			|
	Ribbon Socket---->|...........|				|
			+---------------------------------------+
Code:
  |||||||||||
-+-----------+-
-|           |-
-|           |-
-|   8520PL  |-
-|           |-
-|     U7    |-
-|           |-
-|           |-
-|           |-
-|     ^     |-
-+-----------+-
  |||||||||||
     ||
     | \KBClk (Solder wire here)
     |
      \KBDat (Solder wire here)
Code:
NOTE: I suggest you don't desolder the clk and dat legs of U13 unless necessary!
If you don't get anything when you type and you've double checked
everything else, then consider unsoldering and lifting up those two legs.

     |||||||||||
   -+-----------+-
   -|           |-
   -|           |-
   -| Keyboard  |---KBClk (you may need to desolder + bend up)
   -|  Micro.   |---KBDat (you may need to desolder + bend up)
   -|           |-
   -|    U13    |-
   -|           |-
   -|           |-
/---|     ^     |-
|  -+-----------+-
|    |||||||||||
|
\_KBReset (Solder wire here)
How to connect an A500 keyboard controller to the rev2B A1200 motherboard.

The rev 2B keyboard connector is not 100% A500 compatible. The clk, dat and reset signals are in the right place, but Vcc and GND are not. Also, the pin strip only has seven pins where the A500 keyboard has eight.

Here's what you hook up:

Code:
1.......7
 |||  ||
 |||  |\GND
 |||  \Vcc
 ||\_KBRESET
 |\DAT
 \CLK
Here's the full pinout of the connector:
1-CLK
2-DAT
3-_KBRESET
4-_RESET
5-NC
6-Vcc
7-GND

Note, _RESET is the system reset signal, you want to keep Gayle in charge and use _KBRESET. Similarly, on the A500, Gary is in charge of making a _RESET out of _KBRESET.

Here's a picture:
http://jope.fi/amiga/rev2bkeyboard.jpg

Last edited by Jope; 20 December 2011 at 15:34.
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