Quick question on chip A5 pin 11 on a 5200

[thomas3120]

Hello,

Just received an Atari 5200 which is in excellent shape including mainboard.

I'm planning on doing the UAV mod to it.

RF shields were in place and appears that no modifications have been done.

I noticed chip A5 (GTIA)? had pin 11 lifted.  Was wondering if this is something Atari did at factory.

It's a 2 port model C021376 REV. 1

Here is the picture:

Edited January 9, 2022 by thomas3120

[+x=usr(1536)]

Yep, that's a normal factory modification on a 2-port.

[thomas3120]

On 1/9/2022 at 3:08 PM, x=usr(1536) said:

Yep, that's a normal factory modification on a 2-port.

Thanks for the reply!

Just wanted to make sure.

[+-^CrossBow^-]

I've seen that several times on 2 port units, but I've also seen it inserted with the rest of the pins on some 2 port units also and not seen any differences in behavior either way.

 

[+Stephen]

I believe that pin is "Trigger 3".  On the 8-bit computers, the GTIA uses 3 of the 4 trigger lines as inputs, for the Start, Select, and Option keys.  The 4th trigger is an output, and makes the (annoying as hell IMHO) keyclick noise.  It can also be used to create a 4th digital channel for volume only music.  If you've ever played the game Night Mission Pinball, all the sounds are created with the GTIA.  I'm not sure why it would not be used on the 5200.