Atari65XE board question

[greggj]

This is probably the same board that would be shipped in 130XE, with extra ram chips missing here. 

Question, is it easy to repopulate those? 

 

Also, there's a little bodge on the board. Is that stock ? 

[TGB1718]

21 minutes ago, greggj said:

Also, there's a little bodge on the board. Is that stock ? 

There were a lot of those kinds of "fixes" done at the factory, so it may well be just that.

 

Can't remember if all you need to do it fit the extra chips, sure someone else will let you know the procedure to 128K

[Beeblebrox]

You need the extra 64k of Ram chips added (socket first of course), and the EMMU chip (U34) added:

 

 

EDIT: ...yup a common factory bodge, I've seen in i almost all XE's I've come across (here's one of my 65XEs):

 

 

I always replace the 74LS08 with the 74F08 chip and replicate this bodge on the underside of the pcb)

Edited August 8, 2023 by Beeblebrox

[TGB1718]

Looking at your photo and what @Beeblebrox has posted, looks like you'll have to rewire a few resistors that currently

occupy the U34 space to fit a socket

[greggj]

U35 is also missing on my board. So I do wonder if it's needed. I need to download 130XE manual 

[Beeblebrox]

1 minute ago, greggj said:

U35 is also missing on my board. So I do wonder if it's needed. I need to download 130XE manual 

nope, U35 is not needed. It's not present on any of my 130XE or 65XE machines.

 

[Beeblebrox]

@greggjOf course you could install an U1MB.

 

For U1MB it's less work than socketing RAM, U34, etc. Socket the MMU, the OS rom and socket/replace the 74LS08 with 74F08, (replicating factory wire bodge under the pcb). Then wire up the 4 x signals to the CPU through nearby connecting vias on the PCB. I can show you how if you like. Done it many times on all models of XL/XE.

 

I have a spare 20 pin socket for the mmu and I can send you the 74F08 if you like. PM me.

 

You can get the os socket (28pin) here:

 

https://www.ebay.co.uk/itm/254388306359

 

 

U1MB from here:

https://retrolemon.co.uk/atari-8bit-upgrades/21-ultimate-1mb.html

 

EDIT: BTW whilst in there I'd replace the XE's horrible video output with something like a UGV. All my XE's have it. Cheap and the video output is great.

 

Edited August 8, 2023 by Beeblebrox

[greggj]

I don't fully understand the need to replace 7408 with 74F08 @Beeblebrox ,  had a look at mouser - no longer manufactured (there's a surprise). 

Is 1MB upgrade fully compatible with 130XE "stock"?

 

I need to check keyboard on this machine, I hope it works well

And get DVI output, without Sophia (for now). 

 

I got another 65XE coming Today and 800XL (apparently in non working condition) to play with later. That's me sorted in terms of projects in August 🙂

 

[Beeblebrox]

Replacing the 74LS08 (not 7408) with a more stable 74F08 is a widely known stability fix. It's mainly in the event you want to use either a Side3 cart and/or an U1MB upgrade. I just mentioned it's worth doing if you are in there anyway. If just upgrading the 65XE to make it a 130XE and not using Side3 then no need to. I just mentioned U1MB as if you are upgrading the 65XE anyway, why not just invest a little more. U1MB gives you way more than just a ram upgrade. Coupled with Side3 you get a lot.

 

https://atari8.co.uk/firmware/ultimate-1mb/

 

https://atari8.co.uk/firmware/side3/

 

(Note the cheaper U1MB without Flashjazzcat's firmware pre-flashed will come with the original Candle 2012 firmware so you'd need to flash it. Or pay the extra and get the version with FJC's firmware pre-flashed). I always just buy the cheaper, flash it, then pay FJC (Jon) the difference directly.

 

You can flash the U1MB firmware using an SIO2PC USB.

 

U1MB will install in a stock 65XE or 130XE yes. You just need to socketed the MMU, OS rom, etc as mentioned in my previous reply.

 

74F08's are cheap and readily available on Ebay UK. I'll send you one for free but they are cheap, see:

 

6 x 74F08PC DIP-14 QUAD 2-INPUT AND GATE =MC74F08N 74F08N SN74F08N 

https://www.ebay.co.uk/itm/225089484559

 

Sophia 2 is great but not being made at present. UGV is cheap (I get mine from a really nice bloke on Ebay preassembled for £25). It replaces stock video (you socket the GTIA chip). If you have your heart set on Sophia 2 (don't blame ya), then if/as and when it's available again, remember you'll need to cut a hole in your XE's casing to mount the DVI. Also in order to fit it you'll likely need to remove the RF modulator, where you'll then lose stock video out as the RF modulator generates it. (Unlike the RF mod in XLs which can be removed and you'll still retain stock video).

 

 I got another 65XE coming Today and 800XL (apparently in non working condition) to play with later. That's me sorted in terms of projects in August 🙂

 

Nice - yup I do this all the time.

 

Edited August 8, 2023 by Beeblebrox

[xrbrevin]

3 hours ago, greggj said:

U35 is also missing on my board. So I do wonder if it's needed. I need to download 130XE manual 

U35 is required if you use a programmed GAL instead of an original Atari EMMU

im pretty sure its a 74LS95 but there are topics on here that detail the mod in full detail so have a search around 🙃

130XE - Sams ComputerFacts.pdf 130xe Hardware Manual.pdf

Edited August 8, 2023 by xrbrevin
manuals

[TZJB]

2 hours ago, greggj said:

This is probably the same board that would be shipped in 130XE, with extra ram chips missing here. 

Question, is it easy to repopulate those? 

 

Also, there's a little bodge on the board. Is that stock ? 

 

The extra wiring is from the factory. It is present in most 800XE, 65XE and 130XE.

 

There are several options to upgrade the memory including well designed SRAM upgrades from TFHH and others.

 

I have upgraded most of my 65XE/130XE to 320KB using 8x 41256 DRAM instead of 8x 4164 DRAM which would otherwise make it a standard 128KB. Instead of the 16 pin Atari U34 C025953 PAL, I use the 20 pin GAL16V8 design from TFHH in an article posted on Exxosforum https://exxosforum.co.uk/forum/viewtopic.php?t=160. This article shows both 128KB and 320KB upgrades and does require U35 74LS95 for the latter, to allow bank switching of the extra 256KB memory to Antic mode if necessary. Either way you will need the U34 EMMU in one form or another to allow a memory expansion to work with standard DRAM.

 

A U1MB upgrade replaces the U34 PAL/GAL with another custom designed EMMU.

[Mathy]

Hello guys

 

U35 is a 74LS95B.  I'm the one who discovered that years ago.  Guus Assmann tested it, my suspicion was correct.  Here's what you need to know.

 

I've upgrade both my 65XE and my 800XE to 128kB.  Take out the zero Ohm resistors where it says "U34" and put a socket in the holes.  Use sockets for the extra RAM too.  I've added the capacitors (next to the RAM chips too).

 

Sincerely

 

Mathy

 

[reifsnyderb]

74F08's have a lot shorter transition time than a 74LS08.  Since Phi2 is buffered through the 74LS08, swapping out the 74LS08 with a 74F08 will mean that there is less of a delay between when the input changes and it's associated output.

[Peri Noid]

As far as I know, it's not only the matter of propagation time but also of capacitance of the output - one can connect more inputs to one output and lines may be longer.

[manterola]

I would recommend to use some other RAM expansion since the U34 EMMU is hard to obtain, and also you will need to populate/solder all those chip slots.

Something like SysCheck, that not only expand the RAM to 512KB, but also allow you to select among a set of different OSs, and it is external (you can move it to another Atari), or some of the variety of modern Internal and External expansion would be better option (like U1M, tf_hh internal 512KB or AvgCart). 

I did something similar with my 65XE, but the 2 chips ram version, I installed the 2 RAM chips, the EMMU, but then, not long after I got a SysCheck so I could run some demos and games that need >128KB.

 

Edited August 8, 2023 by manterola

[reifsnyderb]

1 hour ago, manterola said:

I would recommend to use some other RAM expansion since the U34 EMMU is hard to obtain, and also you will need to populate/solder all those chip slots.

Something like SysCheck, that not only expand the RAM to 512KB, but also allow you to select among a set of different OSs, and it is external (you can move it to another Atari), or some of the variety of modern Internal and External expansion would be better option (like U1M, tf_hh internal 512KB or AvgCart). 

I did something similar with my 65XE, but the 2 chips ram version, I installed the 2 RAM chips, the EMMU, but then, not long after I got a SysCheck so I could run some demos and games that need >128KB.

 

Good point!  I just realized you have an ECI on that board as well.  Personally, I'd run it with a 1090.   🙂

 

[greggj]

Thanks for all the answers. 

I got 3 of these machines, and they all work. One of them had to get a replacement GTIA 3 years ago - but all good now. 

So one of them is going to get U1MB, another one will get 130XE upgrade and last one will be left alone in stock condition. 

 

Now I need to find out how to take the key caps without breaking the little stems on them, because I already broke 3 on one of these machines before. 

[Beeblebrox]

34 minutes ago, greggj said:

 

 

Now I need to find out how to take the key caps without breaking the little stems on them, because I already broke 3 on one of these machines before. 

Can you be more specific? There are 2 x types of XE keyboard and several (4/5) of the XL (800XL/600XL) keyboards.

Best thing to do is take pics of all and upload them here, including opening up each computer and uploading pics of the back of the keyboards.

 

EDIT: Also why are you trying to remove the keycaps?

 

 

 

Edited August 9, 2023 by Beeblebrox

[greggj]

You're right, I took the same key of all 3 and one of them has different keyboard to the other two. 

In any case, the middle "Stem" bit broke off on few keys when I was taking this keyboard out to clean it. It was shipped to me in absolutely super filthy state! 

 

Don't have a picture of the broken one - I tried superglueing it - but it doesn't fit in well anymore. So it's sort of stuffed atm, but I dread for the future where I'd want to retrobrite the keys or something. 

And one spring was missing, which I don't know how's that possible

 

 

For completion, the other keyboard that's different, has larger white "barrel" types of key "stems" , and no springs. 

 

 

[Beeblebrox]

Ah so you are talking about the XEs. It's always good to clarify as you have XL and XE machines.

 

So there are two types of XE keyboards for the 65XE/130XE/800XE which can be used in all three. (The XEGS keyboard is a different shape/config).

 

The two XE types are both mylar/membrane types, with one being rubber domes, and the other spring/plungers, (where each has it's own dedicated type of mylar that can't be used in the other). 

 

The springs and rubber cups in either can go missing so maybe a previous owner had a tinker and lost you spring.

 

I "think" you can 3D print replacement connectors AFAIK

 

I'll see if I can dig out pics of the two different types of XE keyboard.

 

In the meantime see here for the twp types of mylar:

 

 

EDIT: See here for a video I found showing the plunger/spring type of XE keyboard:

 

 

Edited August 9, 2023 by Beeblebrox

[manterola]

I got one of these in ebay or AliExpress...

[Beeblebrox]

 

 

or

 

 

...also work well.... 

[TGB1718]

Or just a couple of pieces of wire

 

[deffroe]

6 hours ago, TGB1718 said:

Or just a couple of pieces of wire

 

You're sounding more Yorkshire than Lincolnshire with that post!!

[TGB1718]

3 hours ago, deffroe said:

You're sounding more Yorkshire than Lincolnshire with that post!!

It's how you get after living in the middle of a great big field for years on end 🤣