Atari 130XE with 320k Upgrade Boots to Self-Test

[1050]

I'm your huckleberry.

 

It could be anything memory related at this point and reminding me of boarderline timing issue since the machine does work to some extent while reporting ram that doesn't - and that just doesn't compute.

 

I'd suggest a change of U18 from 74LS08 to 74HCT08 for a stronger phase 2 clock signal as I always do for these boarderline timing cases. But after that and if there are still issues, anybodies guess is as valid. In other words I have not a clue at the moment outside of the weak phase 2 clock that often plagues some machines.

 

I also haven't done EMMU either, but did have a timing issue with a home rolled MMU and only concerning the timing when printing. On a hunch dropped back in the PAL MMU that came out and I was back to printing. Odd, but that happened here. Otherwise the GAL MMU worked fine. I only did the GAL because I could and it worked fine half a year or so and then I needed to do printing. Did get some faster and slower GALs in but didn't burn them so no results if that was a fix or not.

[Mathy]

Hello Nezgar

 

20 hours ago, Nezgar said:

Edit: Does anyone think it could be the EMMU (CO25953) or FREDDIE (CO61991)? Looks like the EMMU can also be programmed to a GAL16V8 like the MMU, if socketed it would fill the unoccupied 4 through-holes: https://www.atarimax.com/jindroush.atari.org/achemmu.html I've made a working XE/XE MMU with a GAL16V8, I haven't tried making an EMMU yet.

 

Good old Jindroush found that information here on my Special Stuff Page.  I found out that the text in the 130XE schematic said U35 is a 74LS95B.  I talked to both Christopher Lang and Guus Assmann about my suspicion and they confirmed that my suspicion was correct.  I can't remember which part Chris and which part Guus played, but at least one of them tested it out and it worked.

 

Sincerely

 

Mathy

 

[eightbit]

Guess I am old school. I use a normal plug in solder iron, flux and solder braid. But I will say I am dreaming of owning that Hakko one day!

[Mclaneinc]

On 11/24/2019 at 7:34 PM, flashjazzcat said:

For anyone who can't afford or can't justify the Hakko, this is a good cheap alternative:

 

The ZD-915 was on offer from one reputable vendor for 55 GBP or so a few months back.

Jon, just found this while looking about at the item you have...

 

 

[Bee]

I used a Weller 13w Blue as my daily driver for over 35 years.  I did a big batch of boards by hand, 88 boards, 122 Joints a board.  I bought the Hakko, it is well worth it if you have a use for it.  I did 10k + joints in just under 2 weeks in my spare time.  Not 1 of those 88 board have failed and it's been a year.  If you are a hobby user that solders once a month, don't get the Hakko.  If you solder almost every day, do get it. 

 

I hope that helps

 

Thank you

 

Edited January 1, 2020 by Bee