Ultimate 1MB in 1200XL?

[flashjazzcat]

Ironically, after such a smooth run of installations in a variety of 1200XLs, this latest machine exhibited stability issues on Friday night of just the kind described by DrVenkman: corruption of the (original) BIOS setup menu, and the entire BIOS display occasionally replaced by reverse video double quotes. Of specific note was the time/date line which is continually displayed in the lower part of the screen in the original BIOS: this would sometimes take a moment to appear, or would appear as a line of reverse video quotes. The RTC - initially at least - was not updating at all, but in this case I could find no fault on the Ultimate board itself.

The following troubleshooting steps were performed over a number of hours:

 

• Ultimate board swapped with one from another machine
• MMU/OS ROM ribbon cables swapped with another machine
• PLCC flash ROM from new board swapped out, and tested in a different board
• CPU changed
• Antic changed
• Base RAM changed (the time/date line resides in the $D600-$D7FF area of base RAM)
• P2 hookups completely replaced, taking Phi2 directly from the CPU
• 74LS08 changed (inconveniently, since I'd already piggy-backed another LS08 on top of it in order to general EXTSEL)

None of the above steps had any effect whatsoever. Then I finally recalled advice I'd received from Candle regarding a troublesome 800XL which exhibited freezing issues after Ultimate was fitted: change the 74LS158 multiplexer. I did this (stealing an IC from a socketed 800XL), and issues appear to have vanished, although there's more work to do on the machine which could still yet upset bus stability. I won't know for sure that replacing 74LS158 has fixed the problem until everything is completed and I run RWCRC on the hard disk, flash the BIOS, etc.

 

Regardless: swapping ICs (especially CPU, 74LS08 and 64LS158) is well worth trying if you have garbage in the BIOS menu, and this applies to ANY machine - not just the 1200XL.

 

As for the jumper settings on the 1200XL, I see the answer is right in this thread:

 

http://atariage.com/forums/topic/224151-ultimate-1mb-in-1200xl/?do=findComment&comment=2966292

 

However, it makes no practical difference here (once Ultimate is installed) whether W12 and W13 are left connected. I haven't tried removing W11 yet, and I'm not sure what effect these changes would have were Ultimate uninstalled and a 28-pin masked OS ROM fitted.

[flashjazzcat]

The LONG saga of this particular 1200XL finally reached a conclusion, thanks to Matthias Reichl (Hias), who deduced from video footage of the corrupted BIOS setup menu that the IO RAM could be inopportunely disabled by a noisy reset line. The suggested fix (unlike anything else previously attempted) which appears to have cured all issues is a 100pF capacitor between Reset and GND on the Ultimate 1MB. I chose a GND pin on the PLCC flash ROM:

 

 

Needless to say, I have a lot more testing to do before I'm 100 per cent certain it's completely fixed, but initial results are very encouraging indeed, with no trace of menu corruption or other unexpected behaviours.

[Frankie]

I made this fix on my 1200xl and all my U1MB setting problems went away too!

[flashjazzcat]

I made this fix on my 1200xl and all my U1MB setting problems went away too!

Fantastic!

[Smokeless Joe]

Ooo, I am conflicted about this. I only have one U1MB and it's working great in one 1200xl (but not the other) so I'm reluctant to scroo with it. On the other hand, it would be the cause of much celebration if it worked, and I would buy Hias many drinks of his choice.

[flashjazzcat]

It's all good testing.

[fujidude]

The LONG saga of this particular 1200XL finally reached a conclusion, thanks to Matthias Reichl (Hias), who deduced from video footage of the corrupted BIOS setup menu that the IO RAM could be inopportunely disabled by a noisy reset line. The suggested fix (unlike anything else previously attempted) which appears to have cured all issues is a 100pF capacitor between Reset and GND on the Ultimate 1MB. I chose a GND pin on the PLCC flash ROM:

 

DSCF6195 (2).JPG

 

Needless to say, I have a lot more testing to do before I'm 100 per cent certain it's completely fixed, but initial results are very encouraging indeed, with no trace of menu corruption or other unexpected behaviours.

 

Sounds like there may be some cause for 1200XL owners to rejoice! It's always good when some pesky problem like that gets handled. BTW, is that flux I see on many spots on the board? If so, I find this stuff to work good at cleaning boards. It's plastic safe, leaves no residue, evaporates fast, is very economically priced, and easy to find at automotive stores; at least where I live. I've literally hosed down boards with this stuff blasting crud and crust. Works like a charm. I see CRC has world wide distribution, but not sure if same products are available in all markets.

[flashjazzcat]

While doing some last-minute BIOS testing, I hit the 1200XL lock-up problem again (screen goes black on Help+Reset and never comes back until the machine is power-cycled, at which point the NVRAM contents are lost). Since it appeared my software fix hadn't worked, I was sufficiently intrigued to try and eliminate the VBXE display. Sure enough, switching over to the legacy output revealed that we had in fact made it into the BIOS menu:

 

 

Look familar? That's right: no IO RAM, exactly the same as the 1200XL from Hell I just fixed with Hias' cap solution. But this happens to be my own 1200XL which hasn't had the cap fix yet. The upshot of this is that the one 1200XL I assumed to be immune from the noisy reset issue appears to exhibit it after all.

 

Let's see if the cap fixes this one too...

 

[flashjazzcat]

Cap fitted, and punching Help+Reset hasn't replicated the issue... yet.

 

EDIT: I guess the VBXE display was going off owing to $D600-$D7FF being completely wiped out with zeros without the IO RAM present to cover the VBXE hardware registers.

Edited March 29, 2016 by flashjazzcat

[fujidude]

"A cap a day will keep the crap away..."

[Smokeless Joe]

I finally found the time and courage to try the 100pF capacitor fix. I almost works without error. With just the (cap fixed) U1MB, I can hit Help+Reset all day and I never lose NVRAM contents. But if I put my SIDE2 cart in, about 1/5 of the time I'll get a goofy screen like one of the below:

 

 

If I power down at this point, I usually won't lose NVRAM contents.

 

Although, now that I think about it, I'm using an older version of FJC's alt BIOS. Lemme try upgrading and see if that helps. Hmm...

[Smokeless Joe]

Strange, FJC's new BIOS helps a lot. The system will still sometimes give a blank screen when Help+Reset is pressed (maybe 1/10 of the time) but trying Help+Rest again or cycling the power brings it back with no loss of NVRAM content. There's still something screwy with this 1200XL and its relationship to the U1MB with a SIDE2 cart, but it's practically functional, which is a lot better that it was. Qualified hooray!

[flashjazzcat]

Try replacing 74LS08 and/or 74LS138 for a start to improve SIDE stability.

[Beetle]

Hi,

 

its great that you were able to sort it out! I was waiting for the solution before i finally placed my U1MB order...

[Beetle]

Hi there,

 

After installing my U1M in the VBXE and Rapidus upgraded 1200XL, i got a quite unstable system.

Rapidus would often interrupt with "Fatal: Cart ROM change detected" message and sometimes

i was stuck with garbage in the gr.0 font.

 

I applied the cap patch FJC described and the font issue didn't appear any longer,

but i had instable system still. Also after quitting Rapidus menu or ultimate setup system

did not reboot but hang with black screen.

 

I remembered about my issue with the BlackBox in my 1250XLD. On that system, fetching phi2 from

Antic pin 29 instead CPU pin 39 cured all problems. I tried this on this machine here, too.

So far the system seems to behave as desired. I was able to load some programs and to update

ultimate setup to FJC's alternate BIOS (great stuff, man!) and SDX to 4.47.

 

So, i will do some more intensive testing and getting used to my new setup,

but for those with problems on the 1200XL, you might also want to use phi2 from antic pin 29.

 

Its the signal from the CPU, but run through a buffer inside antic. This gives a small delay and

a stronger signal, as far as i was told.

 

cu,

Beetle

[Beetle]

After intensive testing (using the 1200XL for 10h while setting up SDX, which is new to me, as well as testing some programs with Rapidus)

i think its safe to say that my System works as reliable as a stock XL. No unusual hickups nor problems with Rapidus or U1MB menu.

[doctor_x]

Cool to know as I eventually would like to mod a 1200 as well.. Never even laid hands on the 1200 as far as I know so I would really like to get into one...

[flashjazzcat]

Didn't work for me (clock from Antic, which in fact made things much worse), but perhaps my board has issues anyway.

[Beetle]

I used an 74HCT08 for the extsel, not the LS type you used.

And mine is PAL, as far Ultimate Setup knows.

[flashjazzcat]

Yep: PAL here too, but I must try HCT chip.

[Beetle]

Thats how it looks in my setup:

 

 

[flashjazzcat]

I used an 74HCT08 for the extsel, not the LS type you used.

And mine is PAL, as far Ultimate Setup knows.

 

Found a pair of 74HCT08s in the spares box, replaced EXTSEL signal, no change. Tried taking Phi2 from Antic as well: no different. Aside from the unwanted reboots and periodic black-screen lock-ups, one symptom is that TLW (when it manages to load) blows up as soon as I press a key. Pasiu emailed me some time ago saying he had to fit pullups on A0-A15 to get things working, but since the board here exhibits some other strange behaviours I may in fact be wasting my time. Emailed Lotharek suggesting an RMA and as soon as he decides to acknowledge that suggestion in one of his emails, that'll probably be the easiest path.

[flashjazzcat]

Found another 1200XL which absolutely needed the 100pf cap fix on U1MB last week (I'd installed U1MB before the fix was available and the machine was back for unrelated repairs). Blew up with new BIOS and cap on the reset line fixed it. I really think this should be a routine mod on U1MB in 1200XLs, short of having the cap incorporated into the board itself (it does no harm on other machines and may even be beneficial on 800XLs, etc).

[+slx]

For information, here are the VIAs I used when installing the Ultimate 1MB:

 

1200XL_Ultimate1MB_Hookup_Points.jpg

 

Sorry the picture isn't better.

I installed my U1MB in a PALified 1200XL using these VIAs and it seems to work normally with the BIOS coming up with Help, SpartaDOS booting when enabled, etc.

 

The only thing that doesnt seem to work are cartridges. When I boot with a cart inserted I get to the self-test.

 

Im not sure if this is a sign of a wrong installation or if theres a trick to booting carts. Im still on the original firmware and need to flash the FJC firmware.

 

I also removed the datain/dataout capacitors and replaced C2 with a radial cap as I broke off the original when installing the pickup.

[flashjazzcat]

Turn off 'SIDE Hardware'. If carts still don't work after that, it's an installation issue.