Modding a 1200XL

[DocRotCod]

Ok so i've searched this over and over but cannot find a direct answer to what I am trying to do here.

 

I have a 1200XL that I am just wanting to port over the 800XL OS and Basic. The FAQ that Bob Wooley assumes you are also wanting to install the PBI, another is assuming you want to do other things. I simply want to use the 800XL OS and Basic. What I assume is install 28 pin socket, install 16K OS in 28 pin socket. Install basic in other socket while lifting pins 21 and 24. Redo jumpers accordingly. Solder wires. Install MMU from 800XL. Done. Am I correct?

[Fletch]

Don't remember much about the install, but I have this in my 1200XL - http://www.atarimax.com/warpos/documentation/

[oracle_jedi]

Correct, I did this on my 1200XL and stopped after I had the OS installed, since holding down OPTION to disable BASIC gets old. You are left with an 800XL in a 1200XL case but no PBI. The LEDs still operate during memory test if you leave it as stock 64K.

 

From the Bob Woolley upgrade published at http://retrobits.net/atari/pbi.shtml

 

(With a little reformatting)

 

All you need to do is pull the 24 pin socket at U13 and solder in a 28 pin unit. One more address line (A13) is needed, so remove the W6 jumper and solder a wire from pin 23 of the CPU chip (U21) to the top pad of W6.

 

Now, plug the 800XL OS ROM into U13.

 

The 16K ROM select is just as simple. Take a look inside your 1200XL. See the chip that has 20 pins (U14)? That is your MMU. It is the main difference between a 1200XL and an 800XL. Same number of little pins, same number of inputs and outputs ..... But the 800XL IC has the 16K select for the OS ROM.

 

So, lets jump right in and swap the MMU with the 800XL part (CO61618). Fits just fine, doesn't it? Pull out all the jumpers except W11, W12 and W9 and you have a ROM select line that will select the address range from $C000 to $FFFF in a single ROM, like the 800XL.

 

Since the 1200XL has two ROM sockets, and there may be some hard core nuts out there that just must have the internal Basic ROM, get a version C ROM and bend up pins 24 and 21. Plug this ROM into U12 and solder a wire from pin 24 of the Basic ROM to +5v at the top of C11 (just to the left of U13).

 

Solder another wire from pin 21 of the ROM to the left hand pad of W7 (which should not have a jumper in it). One more wire from pin 18 of U14 to pin 11 of U23 and your machine has Basic under the covers, just like the big guys!

[+bob1200xl]

Changing to the 800XL OS and adding BASIC can be done by itself - PBI or not.

 

I don't like the idea of soldering (or even using) a "C" ROM, but that is the simplest path. I should do up something with a cleaner install...

 

Bob

[+Guitarman]

I wrote a very detailed set by step mod based on Bob's PBI upgrade and AtariMax's 32in1 upgrade.

 

See it here

Edited October 10, 2012 by Guitarman

[DocRotCod]

Thanks guys... I appreciate the info. I wouldn't be opposed to doing the PBI part, but I think if I did it I would like to do some sort of PCB edge connector and mount it to the case. If anyone here has some extra MMU chips for this upgrade, especially after upgrading to the U1MB, i'd be interested in getting some.

 

Otherwise I guess I need to get a burner that can do GALs.

[BillC]

Thanks guys... I appreciate the info. I wouldn't be opposed to doing the PBI part, but I think if I did it I would like to do some sort of PCB edge connector and mount it to the case. If anyone here has some extra MMU chips for this upgrade, especially after upgrading to the U1MB, i'd be interested in getting some.

 

Otherwise I guess I need to get a burner that can do GALs.

Oops - mistakenly hit the wrong button

[Atari8bitCarts]

Ok so i've searched this over and over but cannot find a direct answer to what I am trying to do here.

 

I have a 1200XL that I am just wanting to port over the 800XL OS and Basic. The FAQ that Bob Wooley assumes you are also wanting to install the PBI, another is assuming you want to do other things. I simply want to use the 800XL OS and Basic. What I assume is install 28 pin socket, install 16K OS in 28 pin socket. Install basic in other socket while lifting pins 21 and 24. Redo jumpers accordingly. Solder wires. Install MMU from 800XL. Done. Am I correct?

 

Maybe this has been presented as an alternative, but I would use Atarimax's 32in1 OS for 1200XL. I have it on one of my 800XL's and it rocks!

 

http://www.atarimax.com/warpos/documentation/

[+bob1200xl]

The internal PBI hack is not a good idea. If you just have to get a PBI, use the external version that plugs into the cartridge port.

 

I can make GALs for you.

 

Bob

 

 

 

 

Thanks guys... I appreciate the info. I wouldn't be opposed to doing the PBI part, but I think if I did it I would like to do some sort of PCB edge connector and mount it to the case. If anyone here has some extra MMU chips for this upgrade, especially after upgrading to the U1MB, i'd be interested in getting some.

 

Otherwise I guess I need to get a burner that can do GALs.

[DocRotCod]

Thanks Bob!

 

Just finished and everything works great! (Except the keyboard, now I gotta fix that).

 

I'll let you know on the GALs. It just seemed to me there would be a surplus out there with people installing 100's of the Ultimate1MB boards.

 

Thomas