Using an EGA in an ATT6300

[slif at oliveb.UUCP]

In article <492 at uvm-gen.UUCP> haviland at uvm-gen.UUCP writes:
>    Is there anyone out there with experience in using a graphics adapter
>    on an AT&T 6300 other than the one that comes with it (such as an EGA
>    card)?  The slots in the 6300 are supposedly IBM compatable as regards
>    memory boards and such, but since AT&T developed their own graphics
>    adapter, I'm not sure if you can get around it.  The adapter itself
>    is not in a normal slot but seems to be off the end of the bus.

  Caveat:  I am not representing Olivetti in any way through this
	discussion.  For that matter, I am not purporting to be an expert
	or guaranteeing any results.  I am not liable for anyone's usage
	of this information.

  There are several things that you need to do:

	1. Disable the indigenous video controller. 
	   If you have the rev. P8 board, you're in luck !! There is
	   a jumper W1 near C11. Jumper pin 1 and 2.  This disables the board.

	   If you have the rev. P4 (most machines do), two things can be done.
   	   AT&T may sell a "wraparound" connector which take the place of the
	   board.  The machine must be partially disassembled to replace the
	   video controller.  A good hand-eye coordination test !

	   The other procedure requires de-soldering a 74LS00 near the buss
	   connector and installing a DIP socket.  Place a header in the
	   socket which has pins 3 and 14 jumpered, and pins 6,7 and 8 jumpered
	   separately.  Make sure you know where pin 1 is, and you did a clean
	   job of de-soldering the IC.  Forget the warranty if you do this.
	   To re-use the video board, replace the header with a 74LS00.

	2. The bus converter in the earlier production reversed the
	   order of bytes output with a 16-bit OUT DX instruction.  Thus,
	   some EGAs won't work.   There is a solution - I believe you
	   need to get several PALs and a new BIOS ROM set from AT&T,
	   which are installed on the motherboard.   No cuts or jumpers
	   are required.  The motherboard is accessible by removing the
	   bottom outside cover only.

	3. Install the video adapter that you like.