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Ultimate 1MB in 1200XL?


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Having conquered, to my satisfaction, the install of an Ultimate 1MB in an 800XL, I now want to install it in a 1200XL. My very first 1200XL is in the mail as I type (so exciting!) so I'm using the "Atari 1200 XL Home Computer Field Service Manual" and various AtariAge forum posts to plan my attack.

 

I'm particularly grateful for the posts of Candle and Flashjazzcat that include pictures:

 

http://atariage.com/forums/topic/178323-ultimate1mb-preorder-starts/?p=2405659

 

http://atariage.com/forums/topic/219984-1200xl-pal-ultimate/?p=2891342

 

From what I tell, the following needs to be done to install an Ultimate 1MB into a 1200xl:

 

1. Remove the OS ROM chips from U12 and U13 and the MMU chip from U14

 

2. Remove (desolder) the 24-pin socket at U12 and replace it with a 28-pin socket (0.6")

 

3. Remove jumpers W7, W8, W9, W12 and W13 (KEEP W11!)

 

4. Insert socket adapters into sockets (fat cable in U12, skinny cable in U14, red stripe = pin 1)

 

5. Make appropriate connections between Ultimate 1MB and CPU pins 35, 36, 39 and 40

 

6. Make appropriate connections between Ultimate 1MB and socket adapter cables

 

7. Secure Ultimate 1MB to motherboard (a whole other topic in itself)

 

Does that sound right to anyone? Am I missing anything?

 

My concerns:

 

a. What the heck do jumpers W7, W8, W9, W12 and W13 do that require their removal? Why keep jumper W11?

 

b. Bob Woolley's PBI for 1200XL instructions (http://www.retrobits.net/atari/pbi.shtml) for putting an 800XL ROM into a 1200XL include removing jumper W6 and connecting the top pad of W6 with CPU pin 23. Do I need to do that too?

 

 

All feedback welcome. Many thanks in advance!

 

- Joe

Edited by Smokeless Joe
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I think you have everything covered there (just finished installing Ultimate into another 1200XL). The Ultimate can be secured to the MB via nylon spacers and a couple of 3mm holes drilled in shield plate either side of the SIO jack. You'll need to remove the (apparently useless) audio coil which pokes up in that area.

 

Not sure exactly why the jumpers need arranging the way they do, but it concerns the arrangement and size (i.e. number of pins) of ROMs in the OS sockets.

 

The W6 jumper is not required for Ultimate - nor even for the EXTSEL mod (for VBXE).

Edited by flashjazzcat
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Having conquered, to my satisfaction, the install of an Ultimate 1MB in an 800XL, I now want to install it in a 1200XL. My very first 1200XL is in the mail as I type (so exciting!) so I'm using the "Atari 1200 XL Home Computer Field Service Manual" and various AtariAge forum posts to plan my attack.

 

I'm particularly grateful for the posts of Candle and Flashjazzcat that include pictures:

 

http://atariage.com/forums/topic/178323-ultimate1mb-preorder-starts/?p=2405659

 

http://atariage.com/forums/topic/219984-1200xl-pal-ultimate/?p=2891342

 

From what I tell, the following needs to be done to install an Ultimate 1MB into a 1200xl:

 

1. Remove the OS ROM chips from U12 and U13 and the MMU chip from U14

 

2. Remove (desolder) the 24-pin socket at U12 and replace it with a 28-pin socket (0.6")

 

3. Remove jumpers W7, W8, W9, W12 and W13 (KEEP W11!)

 

4. Insert socket adapters into sockets (fat cable in U12, skinny cable in U14, red stripe = pin 1)

 

5. Make appropriate connections between Ultimate 1MB and CPU pins 35, 36, 39 and 40

 

6. Make appropriate connections between Ultimate 1MB and socket adapter cables

 

7. Secure Ultimate 1MB to motherboard (a whole other topic in itself)

 

Does that sound right to anyone? Am I missing anything?

 

My concerns:

 

a. What the heck do jumpers W7, W8, W9, W12 and W13 do that require their removal? Why keep jumper W11?

 

b. Bob Woolley's PBI for 1200XL instructions (http://www.retrobits.net/atari/pbi.shtml) for putting an 800XL ROM into a 1200XL include removing jumper W6 and connecting the top pad of W6 with CPU pin 23. Do I need to do that too?

 

 

All feedback welcome. Many thanks in advance!

 

- Joe

The U1MB was designed to plug into a 28-pin 16K socket, the 1200XL came with the 16K OS split between 2-24pin 8K ROMs(2364). Changing the jumpers(plus some other wiring changes) allows use of a 28-pin 16K EPROM(27128) in just 1 28-pin socket. Many 1200XLs came with 28-pin OS sockets installed so Atari was likely planning to change over once the price of 16K ROMS dropped(the reason for configuration jumpers), but it was discontinued before that happened.

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I'm not so familiar with the U1MB, but you need the jumpers if you are going to plug a 16K EPROM into the socket. Since you are not plugging an IC in there, you probably can do without the jumpers.

 

They deal with the -CS/OE line and A13. W6 is +5v. You don't need any of them on the socket, I expect.

 

Bob

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Yes... I didn't mean to imply that A11 was not needed, just that all the other jumper signals are available from the MMU. So, you may not need to apply them to the U1MB cables.

 

Oddly enough, W11 is for A11, which is also available on the MMU?

 

The point is that using a 16K EPROM in a 1200XL does need specific jumpers/wiring, where the U1MB has different requirements. Don't worry about the 800XL ROM instructions when you are installing a U1MB.

 

Bob

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  • 4 months later...

I finally got around to attempting this and I see that my steps were imprecise.

 

There are jumpers only at W7, W8 and W9, at least on the two 1200XL motherboards I have. I cleared out W12 and W13 just in case, but a jumper must be installed at W11. Many thanks to those who posted pictures of their installs. Without those pictures, I might never have figured out that the missing jumper at W11 was the problem.

 

Also, U12 and U13 were already 28-pin sockets, again, this is on the two 1200XL motherboards I have.

 

So... for the sake of anyone else trying this, please enjoy my attempt at new, improved, simple but complete Ultimate 1MB installation instructions for the 1200XL:

 

 

How I Installed An Ultimate 1MB Into My Atari 1200XL:
1. Remove the OS ROM chips from U12 and U13
2. Remove the MMU chip from U14
3. Remove jumpers W7, W8, W9
4. Clear the holes from jumpers W12 and W13 [this step may not be needed]
5. Add a jumper at W11
6. Insert socket adapters into sockets (fat cable in U12, skinny cable in U14, red stripe = pin 1)
7. Make appropriate connections between Ultimate 1MB and CPU (U21) pins 35, 36, 39 and 40
a. pin 35 = HLT
b. pin 36 = R/W
c. pin 39 = PHI2
d. pin 40 = RST
8. Make appropriate connections between Ultimate 1MB and socket adapter cables (remember, red stripe = pin 1)
9. Secure Ultimate 1MB to motherboard

 

 

My 1200XL is now purring away with the Ultimate 1 MB!

Edited by Smokeless Joe
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  • 5 months later...

Duh, why do I always make things hard then they are. I didn't want to solder onto the CPU directly, and didn't realize how easy it is to trace the cpu pins out to a pad to solder onto.

 

U1MB is installed in my 1200XL. If you told me 20 years ago that I would have a 1MB Atari, I would have laughed in your face. :-)

 

Thanks everyone!

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Duh, why do I always make things hard then they are. I didn't want to solder onto the CPU directly, and didn't realize how easy it is to trace the cpu pins out to a pad to solder onto.

 

U1MB is installed in my 1200XL. If you told me 20 years ago that I would have a 1MB Atari, I would have laughed in your face. :-)

 

Thanks everyone!

I've had a 1MB(Newell) 800XL for over 20 years, a 1MB MIO as well.

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Oh good for you.. :sleep:

 

gozar, congrats on the upgrade...it's fun to live in these times :thumbsup:

I was trying to make the point that 1MB Atari 8-bits weren't unknown back then, just uncommon.

 

What Candle's U1MB has done(besides adding extra features) is simplify the installation enormously if the machine has sockets, to the point nearly anyone can do it.

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I was trying to make the point that 1MB Atari 8-bits weren't unknown back then, just uncommon.

 

What Candle's U1MB has done(besides adding extra features) is simplify the installation enormously if the machine has sockets, to the point nearly anyone can do it.

 

Sorry I replied a little badly. It sounded like you were raining on gozar's parade, but I re-read his post above and I see what you were saying now. It's all good, have a nice evening. :thumbsup: :thumbsup:

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Duh, why do I always make things hard then they are. I didn't want to solder onto the CPU directly, and didn't realize how easy it is to trace the cpu pins out to a pad to solder onto.

 

 

That's a lot smarter than what I did. I thought I read somewhere that there could be problems if the CPU connections were too far away, so I figured I'd remove any chance of that happening. I completely desoldered the entire CPU socket, then resoldered the socket with insulated wires at the necessary holes that could reach to the U1M (see attached picture). It was kinda labor intensive, but my Hakko 808 makes desoldering a breeze.

 

I'm glad this thread is useful! Congratulations on upgrading your 1200XL!

 

-Joe

post-36974-0-34508600-1422384466_thumb.jpg

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For future reference: it would be easier to solder the wires to the underside of the board. :)

I wondered about that. Wouldn't you then need to run the wires around the board to the top? And you'd need pretty short leads on the wires since you wouldn't be able to trim them from the top. Something about that seems very unaesthetic to me. Still, it would be a lot less work!

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