Bear (and Porridge) do the Atari 800XLF Cha, Cha, Char

Charlie

.. . Mouse . ..
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Porridge: Charlie's been a-fiddling with his new Atari
BitBBH: But as he knows b*gger all about them...
Porridge: ...he asked if we would finish the job for him

Porridge: You know, Bear, for a children's TV presenter you can be very rude at times!

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-Tools of the Trade-

BitBBH: You won't need a magnifying glass to see my tool!
Porridge: -Sigh- Remember kiddies are watching, Bear

BitBBH: Mmm, sweet little children - yummy!


Porridge: ...Happily Charlie's already bought the parts, and taken his Atari apart, so why don't we see what we've got?

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-Atari 800XLF Motherboard-

BitBBH: Oo, oo, I know this one! Didn't Atari initially conceive this line of computers as a games console to replace the 2600? But because of the games console crash decided to make a line of home computers instead
Porridge: Yes you are quite right, Bear. Impressive knowledge, and an impressive number of syllables you used too
BitBBH: I know more! Considering the original 400 and 800 came out in 1979 it's a very advanced system. Lots of chips for all sorts of good stuff... Chips, I like chips

Porridge: Yes indeed. As well as the GTIA and ANTIC (graphics), PIA and POKEY (I/O and sound) Charlie's computer has Freddy. Along with the MMU this could allow efficient paging of more than 64k... are you ok, Bear?
BitBBH: Uh? I think I once eat a child called Freddy
Porridge: Ok, moving on


Porridge: All this loveliness makes for a powerful 8Bit computer that also has a lot of potential for upgrades. Here are some Charlie got

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-Ultimate 1Mb memory upgrade-

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-Dual POKEY stereo sound board-

BitBBH: Oh yes! Stereo POKEYs for me to Cha, Cha, Char along to... And a whole megabite has got to be a good thing!
Porridge: Don't you mean 'megabyte'?
BitBBH: I know what I said

Porridge: Ooh-kay. All the chips on Charlie's motherboard are soldered in and as we need the POKEY intact they will have to be hot-aired out. Do you think your tool will be up to the job?
BitBBH: No complaints so far...

Porridge: Well, I'm glad to hear it. How about a photo of the chips you need to remove for the memory board and next time we'll take a closer look at the POKEY upgrade

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-Some Chips-
 

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Porridge: Right. So apart from the dual-POKEY board itself one needs a way of switching between mono and stereo operation in the event of compatibility issues - a switch! This one came with the kit

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-A switch-

BitBBH: That looks like a DPDT On-On rocker switch to me
Porridge: Quite so
BitBBH: But-ugly isn't it? Speaking of which I'm sure I could squeeze something better out of my b...
Porridge: Bear! How indecent! Go away while I tell the children about the other bits


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-The Other Bits-

Porridge: While I deplore Bear's, a-hem, bare faced cheek I do feel changing the supplied RCA connectors with a 3.5mm socket might result in a more pleasing aesthetic - Now I have some peace I'll solder in the upgrade boards and wiring


BitBBH: Porridge! Can you come to the bathroom and see what I've done?

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-Something Bear Did-


Porridge: Well really Bear! I've got better things to do than look at your do-do...

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-Better than Porridge Expected-

Porridge: You know that might be just the job
BitBBH: Certainly a job that brought tears to the eyes I can tell you. Let's got fit it to Charlie's computer


BitBBH: Hey! You've been a-soldering without me. And after all the pain I went to to make a better switch. We'll soon sort that!

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-Wanton destruction?-

Porridge: I suppose we will have to use your switch now. Next time I'll see how we can mount these pleasantly on the plastics
 

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Porridge: Now while Bear is keen on his switch because it's a lot more like the computer's power switch, the two problems with mounting it flush are:
1) It will stick out too far
2) You will end up with ugly screw holes through the case

BitBBH: So Porridge. You look like a rodent - how about you nibble a little adapter-thingy that will slot in to an unused hole on the motherboard...
Porridge: Humph!
1) I'm a bear, not a rat
2) You've never had a sensible idea in your head in your life - you saw me make it earlier
BitBBH: Tetchy

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-Have You Guessed What it is Yet?-

Porridge: Charlie says that if anyone recognises exactly where this slightly abused piece of plastic came from he will send the first correct guesser a special prize


BitBBH: You then glue it to the bottom of the switch to get your custom made device
Porridge: Yes Bear, like I did earlier

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-Still Not Guessed What it is Yet?-


Porridge: Our next picture shows the stages I went through to cut the holes for the new switch and stereo port
BitBBH: I started on the stage, that's why I love the Cha, Cha, Char. Oh, and eating small children - I guess I couldn't have a better job


Porridge: Drill a hole for the 3.5mm port, pop off that square of plastic and file out the hole underneath to the same size as the power switch. Inside I glued a bit of plastic above the hole and drilled it for the screw that will hold the top of the switch...
BitBBH: I worked out if you fill the hole with superglue and put the screw in, when it drys the screw will come out and leave a perfect thread
Porridge: ...a lucky accident. I also made a recess for the shoulder of the 3.5mm connector so it would fit flush


BitBBH: Here's how it looks when put together

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-All Together Now-


Porridge: Here's the result

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-Isn't She Lovely?-

BitBBH: Yes, yes. Very interesting, but I'm getting bored. Can I play yet?
Porridge: All in good time
 

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BitBBH: Bored now! When can we play? When can I Cha, Cha, Char?
Porridge: Well I think it's time we showed the boys and girls more of the internal mods
BitBBH: Ah, the boys and girls. Those happy little faces, I have't had one or two for tea in ages

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-MMU and OS ROM Replaced, extensions for Sally-

Porridge: Top-left and top-right the MMU and OS ROM have been replaced by the main headers for the Ultimate 1Mb. Sally, the Atari version of the 6502 CPU, also has some lines plumbed to the upgrade


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-Ultimate 1Mb in Place-

BitBBH: Yeh, yeh. My feet are itchy, my toes are a-twinkling. I want to dance, do you want to dance Porridge?
Porridge: No


Porridge: Here's the dual-POKEY board in place, populated with a pair of POKEYs. The lower one came from Charlie's 800. Atari manufactured their chipset all over the place, most of his chips come from Mexico

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-POKEY, POKEY-

BitBBH: Mexico? Arriba! Tortillas, tequila, music and dance. Let's party Porridge


Porridge: Here's the whole thing so far. Yes, Bear and I like ribbon cable - ribbon cable is good. I even super-glued two strips of three-core together for the POKEY switch. The extra LED is the stereo function indicator - I'll ask Charlie where he really wants it later

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-The Full Buritto with Salsa-


BitBBH: Salsa is also a kind of dance... Not a patch on the Cha, Cha, Char though

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-Bear Could Wait No-longer-
 

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-And Rest-


Porridge: Must get back to it...

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-Still At It-


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-Fixing the PBI Bus-


BitBBH: And that means..?

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-74LS08 Modification-

Porridge: Well, Charlie said his 800's gotten a bit flaky after these mods and I suspect it's because of trouble with the phase two signal. The story goes like this:
The 02 (phase two) clock signal that comes out of the computer through the cartridge (and PBI) port(s) is buffered from the signal coming directly from the CPU. This buffering adds a small but measurable delay. By the time the signal gets out of the computer and on to your PBI devices, there is more inductance and parasitic capacitance to further delay this signal. When the delay gets too much out of hand, WRITES to the PBI device get corrupted, because the data bus is no longer valid on the trailing edge of 02. I used to swap out the 6502, which would generally fix the problem. However, I found a solution that would work with ALL processors: add in the phase 0 clock input (that goes into the 6502's clock circuit) into the 02 buffer gate. the phase 0 signal is the same as the phase 2, only backwards in time slightly. It so happens that the 02 buffer gate is an AND gate, and has an unused input. Tying this unused input to the phase 0 signal ends up bringing the high-to-low transition back in time, giving us a little more grace for the extra delays that will happen in the outside world.
ON 600XL/800XL COMPUTERS: Solder a wire from pin 4 of the 74LS08 to pin 13 of this same chip.
ON 65XE/130XE COMPUTERS: Solder a wire from pin 4 of the 74LS08 to pin 2 of this same chip.


Charlie has another plan to really sort the CPU clock issues if this doesn't work or if anyone is interested. Got all that?

BitBBH: Er...
 

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Porridge: Don't worry, Bear. Nearly done

BitBBH: Really? Great! Let's plug in the SIDE2 cart because...

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-You Are Reckless!-

Porridge: We've got to put it back together first


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-Nearly There-

BitBBH: Hoorah! All those lovely games
Porridge: And the useful applications
BitBBH: Not to mention the great demos
Porridge: Well, this SIDE2 cart will also work as a hard drive...


BitBBH: ...let's get on with loading the games, eh? Er, Porridge..?

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-It's a Spare Now-

Porridge: The IR shield won't fit with these modifications in place, Bear. C'mon why don't we see what it will do


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-Hey No Wires - Just Like Bands on the Telly-


:)
 

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Quite simply the most entertaining and educational thread I have read...(y)

Amazing stuff Charlie, seriously impressive hand skills there buddy..

But please do send me some of the medication that you are on as I want to share the moment with you :LOL:

Love it buddy, I really want an 800xl now....

TC :)
 
I have seen Bear numerous times with the children but i have never seen any of this extra curricular activity. Love the thread but it definately is one of the weirdest i've ever read :LOL:
 
lol awesome thread.


I plan to install my U1mb and Stereo pokey board sometime this week when I have some free time.
 
Thanks for the kind comments chaps - Bear, Porridge, and I bask in the sunsine of your praise. :D


lol awesome thread.


I plan to install my U1mb and Stereo pokey board sometime this week when I have some free time.

I suspect you know a lot more about these machines than me but if I can be of any help...
...trouble-shooting the U1Mb in mine has been something of an education.

PS
It may be me but I think Lotharek's instructions for the activity LED are the wrong way round. I ended up mounting mine on a small pinheader so I could easily turn it...
...I've got some RGB LEDs (from Tandy). If/when I have time I'll replace the keyboard LED with one for a multi-function indicator - it looks like the keyboard has spare lines on the schematic.

PPS
I also hope your chips are socketed - I suspect the PCBs in these things are built down to a price. Mine didn't like the old hot-air gun at all. But that could be something to do with the unconventional equipment I use. ;)
 
Hmm,
Still getting stability issues with the U1Mb in place...

Porridge is going to replace all the LS IC's with HC ones and replace all the (very old) electrolytic caps to see if that will help.

I've also discovered some info regarding how easily the PH2 wave from Sally can get mangled:

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-This is as good as it gets!-

Start to add stuff and the supposedly square wave-form starts to get delayed (see Porridge's mod) and then collapses, so causing instability.

There seems to be a way to regenerate the PH2 signal with the aid of a cap, a resistor, and a 74HCT123 :

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-Better-

When (if) I've constructed and tested the board I'll post more piccies - of course being a lazy type if Poridge's mods do the job I may not get round to fitting/testing...
 

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PPS
I also hope your chips are socketed - I suspect the PCBs in these things are built down to a price. Mine didn't like the old hot-air gun at all. But that could be something to do with the unconventional equipment I use. ;)

These atari 8 bit machines are known for having delicate boards. You have to be careful when desoldering on them. If you have it, I would suggest a vacuum based desoldering tool.

I don't know exact numbers, but I have read that about 1/3rd or so of the 800xl's have socketed chips. And I imagine those are earlier production machines too.

Good info in this thread.


Sent from my SAMSUNG-SGH-I317 using Tapatalk 2
 
:)

Hmm,
Further digging suggests the 74LS08 mod above, and replacing the LC ic's with HC ones, is not likely to stabilise my 800...

Why?

It seems, quite apart from A8's being a little dodgy in the PHI2 department, the Mexican Sally (Atari 6502c CPU) found in my machine is a particular problem.

Not fair! The Urban Dictionary suggests it ought to be more friendly and helpful...

...ho-hum. It looks like I will have to pull my finger out and make a proper PHI2 regeneration circuit after-all.

More soon.
 
Right,
Bear will have to wait on replacing the caps and LC IC's with HC ones as the company I ordered them from a week ago has just e-mailed me to say they are on holiday until the 12th - Bah! Oh-well, everyone deserves a holiday. Moving on...

Let's get on with the PHI2 regeneration circuit I was muttering about instead:

Components:
1) SMT 74HCT123
2) SMT 33pF capacitor
3) 0.25W 5.6K carbon/metal Film resistor
4) Some Kynar wire
5) Magnifying glass
6) Flux is your friend
7) Using equipment less cr*ppy than mine will save some swearing.

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-Components-

Why these specifics? Because I was going to make a nice little press 'n peel PCB for this mod until I realised there's so little soldering to do it wasn't worth the effort...
...then I realised these components will fit together very nicely anyway with the aid of a little kynar wire.
(I went for a non-SMT resistor because the actual correct value could be anywhere from 5.2K to 5.8K, but 5.6K is easiest to find. If the 5.6K didn't do it I'd have had an easier time swapping components about, if I'd actually done a PCB. Don't use multiple resistors to make up other values, it probably won't work for this circuit!)

Next, wire said components up as follows:
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-Pretty Colours-

I would suggest soldering in the following fashion:
1) Bend/cut the resistor wires short so they connect pins 15/16, solder in place.
2) Use left-over wire to bridge pins 9-11.
3) Kynar wire pins 8 to 9, pins 1 to 8, and pins 3 to 16.
4) Solder flying leads (Kynar) to pins 1, 2, 13, 16

You should find if you got a SMT 74HCT123 and SMT 33pF capacitor that said cap is just long enough to bridge pins 14 and 15...
5) Solder the capacitor to pin 15 (already solder there).
6) Solder the other end of the capacitor to pin 14.

Now for the flying leads:
7) If your Sally (Atari 6502) is socketed pull it out and gently bend up pin 39.
Of course mine isn't which complicates matters!
8 ) Return it to the socket with pin 39 no-longer entering the socket.
9) Where the diagram says S1, S8, S39 solder the flying leads to the socket.
10) Where the diagram says C39 solder the flying lead to the free CPU pin.

In all it's glory:
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-Not So Pretty-

The whole lot should sit nicely on top of your CPU and you'll get a proper square wave clock that won't play silly b*ggers when you add extra components to your system and cause so much pesky inability - Hurrah! :D

*IMPORTANT*
Because my dratted Mexican Sally is soldered to the motherboard I've now got to go and make up my mind what the least destructive method is for lifting pin 39 is before I go solder in this mod...
...piccies will follow shortly - Don't do the above until I've actually built and tested it myself! For now I'm kind of using the tread for my own reference. ;)
 

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Woo-hoo!

It never ceases to amaze me when my mods actually work. :blink:


So here we go:
Full PHI2 stability mod in place (along with a bit of tidying) and confirmed working.

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-Full Burrito with Salsa, More Neatly Done-

-Main ribbon connectors for the Ultimate 1Mb shortened for a neater fit.
-Has my Mexican Sally got a new hat..?


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-The Other Side-

-Remaining Ultimate 1Mb CPU (Sally) and Dual-POKEY (Sally and GTIA) connections routed round the back.


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-New Hat for Sally-

In the end I hot-aired out the CPU to find I didn't have a good socket the right size. So after a bit of custom socket construction that was soldered in...
...ah, there was also the matter of the PHI2 fix wanting some of the same pins as the U1Mb. Hmm, so that (along with the dual-POKEY) got it's connections rerouted under the motherboard...

...for the PHI2 fix itself pin 39 of the CPU was bent up and Sally's new hat then, mostly, soldered to her shoulders. The final connection that needed to be in the now free socket hole under pin 39 got the stub of a turned socket pin soldered to it. With the whole lot pushed home I took a very careful look to make sure old and new pin 39's weren't shorted.
I left Porridge's 74LS08 mod in place. It's probably not needed now but as it won't do any harm and he's such a sensitive little chap I didn't want to upset him.


Yep, it boots. And so far hasn't shown any of the flakiness I'd come to expect from my new toy - My ghast is truly flabbered. :D


At last I can actually have a proper play... Porridge and Bear can do the remaining mods later. Then high time for me to get back to more familiar stuff and do a bit of Acorn modding.
 

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Excellent stuff, I envy your skill in being able to diagnose and repair what, for me, would be an unresolvable issue.
Nice one. (y)
 
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