New 800XL with interesting mods - Anyone know what's going on with these?

[Cheshire Noir]

Hi There,

I'm the proud owner of my first 8 Bit Atari system. I've never used any 8 Bit Atari systems before this.

I purchased this system off EBay and it arrived on Monday.

It's an 800xl at heart, but there's an additional rotary dial on the top right, and a bonus switch on the back right. It also has a Dymo label proclaiming it to be an Atari 260XE.

The machine powers on and seems to run fine.

The rotary dial seems primarily for changing between ROM images (More on that shortly) as the first position brings up a Machine Code Monitor. The other three positions bring up standard looking READY prompts in slightly different shades of Atari blue.

Last night I finally opened it up and...

Well let's just say it's exciting in there.

There's a ROM tower to the right that was poking up through a hole cut in the RF shield and a board slap bang in the middle and about a million "bodge" wires running willy nilly, soldered directly onto various chips. (I have spotted the loose wire and will fix it tonight). There was also quite a lot of rust on the RF shield. The board looks fine.

If I had to guess I'd say these are associated with a RAM upgrade.

 

My questions are:

Does anyone recognise these mods?

Is there any way of finding out what's on the ROMs? (I have a TL866 II+ so I can pull them and read them if that would help)

 

As I mentioned, I'm brand new to all this. Talk about diving in at the deep end

 

I'm working on an SDMax so I hope that I'll be able to load software on shortly, which will give me access to more diagnostics.

 

Thanks in advance!

 

Chesh

 

[BillC]

9 minutes ago, Cheshire Noir said:

My questions are:

Does anyone recognise these mods?

Is there any way of finding out what's on the ROMs? (I have a TL866 II+ so I can pull them and read them if that would help)

The additional PCB and mess of wires are for a 256k upgrade, does not appear to be a commercial version, the wires to the switch on the back are likely to allow disabling the upgrade to  run incompatible software.

 

The top OS chip is a stock XL OS ROM, the EPROM below it contains OMNIMON XL. The other 2 EPROMs aren't marked, you could read them with your TL866 II+ then examine their contents using Omnivore or similar software to see if you can identify them.

 

[+Nezgar]

This is a good RAM tester that will confirm all 192KB of extended RAM in your system:

http://atari.sk/extended-ram-test-0-22-0-xram0220-xex/

 

It would be interesting to confirm that the switch indeed disables the extended RAM as suspected.

 

The ROM's appear to be:

1. Original XL ROM
2. RAMROD/OSNXL/FASTCHIP/OMNIMONXL (But it's a 27128 which is big enough for only 1 OS, so I wonder WHICH of those it is? lol)
3. "ULT" - maybe Ultimon (Similar to Omnimon) - Recently placed into PD and updated by it's original author John Lawson:
   https://atariage.com/forums/topic/209253-ultimon/
   https://ultimon.com/
4. No label - Who knows?

Indeed you can dump the ROM's with your TL866... Or you can also dump them using the Atari itself using the "AtariROMDumper.atr" here:
http://www.wudsn.com/index.php/productions-atari800/tools/atariromchecker

 

You can compare OS checksums for stock Atari-OS's here:

https://www.wudsn.com/productions/atari800/atariromchecker/help/AtariROMChecker.html

 

And you can post the others here for us to compare/identify.

[_The Doctor__]

#2 is a concatenation of all that is listed on it, at least it should be... as was done in a number of users groups, a dump of it should prove interesting, ult could be ultramon or ultraspeed os

very cool spaghetti box!

cover the proms window glass on the last one, any light containing ultraviolet spectrum can start to damage erase some data....

Edited January 20 by _The Doctor__

[StickJock]

18 minutes ago, _The Doctor__ said:

cover the proms window glass on the last one, any light containing ultraviolet spectrum can start to damage erase some data....

Back in 1990, I remember my manager telling me about trying to debug some issue.  Every time they leaned over the system to get a closer look, the problem went away.  When they sat back again, the problem reappeared.  Eventually, they realized that what was going on was that they had not covered the EPROM (as they had been iterating software changes, burning new EPROMs and sticking the old ones back into the UV eraser, so didn't bother to cover them), and when they leaned over it, they shadowed the window and it started acting right, but when they sat back, the EPROM was exposed to the florescent lighting in the office.  There must have been some cell that was right on the hairy edge....

 

Anyway, the moral of the story was to always cover the windows on the EPROMs, even if it is just for a quick test.

[Cheshire Noir]

3 hours ago, StickJock said:

Back in 1990, I remember my manager telling me about trying to debug some issue.  Every time they leaned over the system to get a closer look, the problem went away.  When they sat back again, the problem reappeared.  Eventually, they realized that what was going on was that they had not covered the EPROM (as they had been iterating software changes, burning new EPROMs and sticking the old ones back into the UV eraser, so didn't bother to cover them), and when they leaned over it, they shadowed the window and it started acting right, but when they sat back, the EPROM was exposed to the florescent lighting in the office.  There must have been some cell that was right on the hairy edge....

 

Anyway, the moral of the story was to always cover the windows on the EPROMs, even if it is just for a quick test.

Cheers for all the replies!

I stuck some black tape across the window seconds after taking that photo. 

Once I get the drive working (Just waiting for the final bits and pieces) I'll test that RAM.

 

I dumped the ROMs and text in the ROM with "ULT1" on it suggests it's indeed ULTIROM. Text in the one with the window exposed suggests it's SUPERMON.

 

I've attached all 3 if anyone wanted to poke around them. Thanks again, everyone!

 

Chesh

ULTIMON(3).BIN RAMROD(2).BIN SUPERMON(4).BIN