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whaledriver

Atari 1200XL REV 11 OS install

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I have a spare 1200XL that is completely stock.  Reading about the REV 11 OS got me thinking.  I have a bunch of 2764 Eproms.  I would think it would be possible to program two 8K Eproms and put them in the OS sockets.  I have looked and can't really fine a guide that would show how this is done.  I have the REV 11 rom file but it is 16KB.  I will have to split the file in half (unless someone knows where there is one already in two 8KB files).

 

What changes to the board would I have to make to put in two 28 pin Eproms (besides soldering in two 28pin sockets)

 

Thanks,

Sean

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Burn the latest XEGS OS on to a 27128, set a few jumpers, add one wire, and you can put BASIC in the other socket. Simple.

Follow the first part of Bob Woolley's excellent instructions.

 

First half of instructions pasted below:

 

A Parallel Bus Interface for your 1200XL

By Bob Woolley   SLCC

    If you did the CLEARPIC modification in the August Journal, then
you qualify as a 1200XL nut, just like me. No use fighting it, though,
you really do yearn for the MIO type stuff that all the 800XL/130XE users
have been bragging on. The easy way to get one is to buy an 800XL, but
since when do we have to take the easy way out? Face it, you want an MIO,
you gotta do this mod. You might even get a disk interface thrown in.
There are only two hardware functions that are missing on the 1200XL that
are required to run the Parallel Buss - a 16K ROM select and the
-EXTernal SELect input. All the other circuitry already exists in the
1200XL. So, let's get a 16K ROM in there, first.

     The 1200XL OS does not have the PBI code in either of its two 8K
ROMs, which means we'll have to either recode an EPROM or use the 800XL
or 130XE (same chip) OS ROM. Since many people don't have an EPROM burner
and don't want to spend $150 for one, maybe $5 or $10 for an Atari ROM
out of an 800XL (CO61598B) is a good idea. Also, it really isn't legal to
copy the Atari ROM into an EPROM, even for your own use. Even if you
destroy your source ROM, even. Atari was nice enough to provide an easy
upgrade path, use their ROM. OK? First thing you may find is that the
1200XL ROMs are 24 pin devices and the new ROM is a 28 pin package. No
problem. All of the 1200XL main boards have 28 pin sites for the ROMs.
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 ! Now you get the thrill of holding
down OPTION when you want to boot without Basic, where those of us who
don't do this section only need to pull the cartridge. To be fair,
though, SpartaDos will now turn Basic on and off in your 1200XL with the
Basic On and Basic Off commands - which is kinda nice.

 

Do the simple mods, replace OS and MMU. Put BASIC in the other socket. Simple.

:)

 

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Thanks but this doesn't solve my problem.  Those instructions replace the two 1200XL roms with an 800XL 16KB rom.

 

I am trying to replace both 1200XL roms with two 8KB 28pin Eproms.  I wanted to split the REV11 rom file into two 8KB Eproms and install them in the 1200XL.

 

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Just now, whaledriver said:

I am trying to replace both 1200XL roms with two 8KB 28pin Eproms.  I wanted to split the REV11 rom file into two 8KB Eproms and install them in the 1200XL.

This sounds like a question for @bob1200xl :)

 

That said, I think the "splitting the ROMs part" is just as simple as that - there are dumps of the rev 11 OS that are easily found; use a hex editor to create two x 8K files, one of the first 8K and the second of the second 8K. I can't recall offhand which bank goes into the "A" chip and which the "B" but should be easy enough to try it and swap the positions if you get it wrong.

 

The trickier part, and the part where someone who has literally dozens of 1200XLs can help, is the board jumper configuration for EPROMs versus ROMs. All 3 of my 1200XLs came with mask ROMs so I can't really assist here. I know the jumpers have to be reconfigured for a single 28-pin ROM but I don't know about for two EPROMs. Someone who has a 1200XL equipped with EPROMs should be able to get a photo of the jumpers of the board so you can see if changes are required (this is one of my ROM-equipped machines before installation of a U1MB rearranged things). 

 

 

 

 

InkedIMG_8334_LI.jpg

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First board is a 24-pin ROM setup. Jumpers on W6, W7, W8, W9.

 

Second board is a 28-pin setup. No jumper on W6, Jumper on W11, W12, W13.

 

Bob

 

 

 

DSC01765.thumb.JPG.4b4ba2eac77e7ef2d5eb3dee1081d171.JPG

 

 

DSC01764.thumb.JPG.8acbd5c0851f6bbdda5586e856399c35.JPG

 

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Thanks Bob!  This is exactly what I was looking for.

 

My main 1200XL has many upgrades including the 32 in 1 OS.  This is my spare machine and now has the REV 11 OS.

 

Thanks again!

 

Sean

 

IMG_9525.jpg

IMG_9526.jpg

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1 hour ago, whaledriver said:

If anyone else wants to do this, here is the OS split into two 8Kb files.

 

 

1200XL REV11 OS High 8 kB · 2 downloads 1200XL REV11 OS Low 8 kB · 2 downloads

I have two stock 1200XLs right now, and as of last week I have an EPROM burner as well. I think I know what I'm going to do with one of those 1200XLs. :)

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Damnit, all I'm getting is a red screen of doom and gloom.

Are you supposed to burn them as HEX or Binary?  (Minipro programmer)

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17 minutes ago, leech said:

Damnit, all I'm getting is a red screen of doom and gloom.

Are you supposed to burn them as HEX or Binary?  (Minipro programmer)

Although I did this less than 6 weeks ago, I can't recall what settings I used. Pretty sure you need to use Binary - EPROMS and EEPROMs are not modern microcontrollers that you usually program with Intel Hex format data.

 

If you did use Binary, make sure you've got each chip in the correct socket.

 

 

IMG_5023.JPG

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4 minutes ago, DrVenkman said:

Although I did this less than 6 weeks ago, I can't recall what settings I used. Pretty sure you need to use Binary - EPROMS and EEPROMs are not modern microcontrollers that you usually program with Intel Hex format data.

 

If you did use Binary, make sure you've got each chip in the correct socket.

 

 

IMG_5023.JPG

Hmm, that's what I did.  Verified that I burned the high / low and put them in the right sockets.  Swapped over all the jumpers and... red screen... (jumpers being remove w6, and change w7-9 to w11-13)

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4 minutes ago, leech said:

Hmm, that's what I did.  Verified that I burned the high / low and put them in the right sockets.  Swapped over all the jumpers and... red screen... (jumpers being remove w6, and change w7-9 to w11-13)

Time to pull out your multimeter and verify continuity where you swapped the jumpers to ensure you didn't damage any traces.

 

You did a verify after you burned the EPROMs, correct? Any chance you got the chips or binary files mixed up when you burned them?

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Just now, DrVenkman said:

Time to pull out your multimeter and verify continuity where you swapped the jumpers to ensure you didn't damage any traces.

 

You did a verify after you burned the EPROMs, correct? Any chance you got the chips or binary files mixed up when you burned them?

Yeah, I even popped them back into the programmer to check which Hi/Lo chips were which and then popped them into the sockets one at a time.  Same issue.  So now I am testing to make sure I didn't fry something.  I ended up soldering in pins and then I can just use jumper wires to switch between them instead of having to de-solder / resolder the jumpers every time.

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1)  Make sure you haven't inadvertently got some solder touching the pads on W7-13 that is not supposed to be there (continuity on adjacent pads that shouldn't).  I say shouldn't because I believe there are a few that are supposed to be like that.  Basically make sure you clean up any solder splash on the pads.  I did that once and had a no boot issue.

 

2)  What is the speed of your EPROMs?  Is it 150, 200 or 300 ns?  I have upgraded many 1200XLs with EPROMs with Rev 11 and found a few motherboards that just don't like them.  Not many, but 1 out of every 8 attempts I find that a particular motherboard just won't boot off EPROMs consistently.  Have no clue why some are picky about it.  I can have a failed attempt one one board, put the very same EPROMs on another board and it works great.  If it fails, I've tried another set of EPROMs and it will also consistently fail to boot.  Let me correct myself by using the word "fail".  By fail I mean either it boots inconsistently or will just never boot.  The ones that are inconsistent, usually work if I allow sufficient time between power cycles.  If I turn it off and on again within a second, it might fail, but if I pause with it off for 5 seconds before cycling power, it works.  

 

That being said, the mass majority of times I've tried this upgrade it works 100% first and every try.  Again, have no clue why a few are picky about EPROMs.  Try a different brand of EPROM if you have them.

 

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7 minutes ago, ACML said:

1)  Make sure you haven't inadvertently got some solder touching the pads on W7-13 that is not supposed to be there (continuity on adjacent pads that shouldn't).  I say shouldn't because I believe there are a few that are supposed to be like that.  Basically make sure you clean up any solder splash on the pads.  I did that once and had a no boot issue.

 

2)  What is the speed of your EPROMs?  Is it 150, 200 or 300 ns?  I have upgraded many 1200XLs with EPROMs with Rev 11 and found a few motherboards that just don't like them.  Not many, but 1 out of every 8 attempts I find that a particular motherboard just won't boot off EPROMs consistently.  Have no clue why some are picky about it.  I can have a failed attempt one one board, put the very same EPROMs on another board and it works great.  If it fails, I've tried another set of EPROMs and it will also consistently fail to boot.  Let me correct myself by using the word "fail".  By fail I mean either it boots inconsistently or will just never boot.  The ones that are inconsistent, usually work if I allow sufficient time between power cycles.  If I turn it off and on again within a second, it might fail, but if I pause with it off for 5 seconds before cycling power, it works.  

 

That being said, the mass majority of times I've tried this upgrade it works 100% first and every try.  Again, have no clue why a few are picky about EPROMs.  Try a different brand of EPROM if you have them.

 

So it is booting with the original roms.  Did this so I could switch between them easier... solder job looks pretty clean (yeah there are some that simply connect the same pins.)

 

20200829_162718.jpg

20200829_162517.jpg

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5 minutes ago, leech said:

So it is booting with the original roms.  Did this so I could switch between them easier... solder job looks pretty clean (yeah there are some that simply connect the same pins.)

 

20200829_162718.jpg

20200829_162517.jpg

The -25 means 250 ns.  I've had much luck using -12 or 120 ns EPROMs.  Don't know if the speed matters since the 1200XL will run with 300 ns RAM.  Do you have a 2764 from another manufacturer that you can try?

 

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10 minutes ago, ACML said:

The -25 means 250 ns.  I've had much luck using -12 or 120 ns EPROMs.  Don't know if the speed matters since the 1200XL will run with 300 ns RAM.  Do you have a 2764 from another manufacturer that you can try?

 

Ha, not on hand.  Guess I'll be ordering some!

 

Edit: Ordered 4 of them. 

Edited by leech

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 I used (IIRC) 150 nanosecond 27C64's. I notice you are using 27C128. Did you configure the system for a single 16K EPROM rather than 2 x 8K EPROMs? 

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12 minutes ago, leech said:

Ha, not on hand.  Guess I'll be ordering some!

Also, I noticed you're using the 27128 which if I'm not mistaken is a 16Kx8 (16 EPROM).  Possible theory:  Did you burn the top 8K and Bottom 8K of each chip with a same data?  If not, the high bit (pin 26) maybe floating and its looking for the 8K of the EPROM you left blank.  This can be solved by burning the 8K data on U12 to 0000-1FFF and then repeat the same data on U12 onto 2000-3FFF.  That way if pin 26 is floating, it reads the same data regardless whether its looking at the top or bottom 8K.  Do the same for U13.

 

Also, simply using a 2764 (8K x 8 ) would avoid the issue altogether.

 

Your also in a position to burn 1200 XL rev 11 on U12 on 000-1FFF and burn an additional OS like 800XL on U12 from 2000-3FFF. Do the same for U13.  When you plug them in, bend up pin 26 on both U12 and U13 so it does not go into the socket.  solder a wire from pin 26 U12 to pin 26 U13.  Then solder a wire from pin 26 U12 to the center post of the RF channel 3-4 selector.  Now you have two operating systems that are selectable by using the RF channel 3-4 switch that is already there. 

  

Edited by ACML

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2 minutes ago, DrVenkman said:

 I used (IIRC) 150 nanosecond 27C64's. I notice you are using 27C128. Did you configure the system for a single 16K EPROM rather than 2 x 8K EPROMs? 

Not even sure how to do that, I assume that means I'd need to merge the Hi/Lo into one?

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3 minutes ago, ACML said:

Also, I noticed you're using the 27128 which if I'm not mistaken is a 16Kx8 (16 EPROM).  Possible theory:  Did you burn the top 8K and Bottom 8K of each chip with a same data?  If not, the high bit (pin 26) maybe floating and its looking for the 8K of the EPROM you left blank.  This can be solved by burning the 8K data on U12 to 0000-1FFF and then repeat the same data on U12 onto 2000-3FFF.  That way if pin 26 is floating, it reads the same data regardless whether its looking at the top or bottom 8K.  Do the same for U13.

 

Also, simply using a 2764 (8K x 8 ) would avoid the issue altogether.

 

You also in a position to burn 1200 XL rev 11 on U12 on 000-1FFF and burn an additional OS like 800XL on U12 from 2000-3FFF. Do the same for U13.  When you plug them in, bend up pin 26 on both U12 and U13 so it does not go into the socket.  solder a wire from pin 26 U12 to pin 26 U13.  Then solder a wire from pin 26 U12 to the center post of the RF channel 3-4 selector.  Not you have two operating system that are selectable by using the RF channel 3-4 switch that is already there. 

  

Ha, that's sort of brilliant.  Let me see if I can manage to do that.  I can't recall where I read I was supposed to get the 27128s, but that's what I had ordered.  Much easier to test these things now that I've created the jumper wires.

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If you are using 27128s, you need to replace W6 with a 1K (or anything close) resistor. This will put your code in the upper 8K block of the 27128s.

 

Bob

 

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33 minutes ago, bob1200xl said:

If you are using 27128s, you need to replace W6 with a 1K (or anything close) resistor. This will put your code in the upper 8K block of the 27128s.

 

Bob

 

I'll give that a shot!  I was just about to give up, after programming the upper/lower part of each chip with the same hi/low.  Though that means now I need to dig through my bag of resistor.

Update: No such luck, I'm guessing these eeproms are just not liked by the system.

Edited by leech

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So, got in the AM2764-3DC chips... and MiniPro doesn't seem to like them much... first, the closest match I could fine in the software was the AM2764A (28pin DIP).  So I tried to do the CheckID, and it gave me FF FF.  Tried to read them, and they read fine (all  FFs) and then I tried to program it, and it told me to FF off.

 

I did have a thought though.  I know some 1200XLs only came with 24pin sockets for some reason.  Is it possible this one (having already been messed with before I got it) had some other stuff done to it that would make the 28pins not entirely work?  So even if I got these to burn right, I'd still get a red screen. 

 

So trying to find the right 24pin 8kb chips.

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