400/800 Commercial Memory Upgrades

[ClausB]

Looks like the yellow wire is there just to repair a cut trace on the motherboard.

 

I'll be interested to hear how it works.

[BillC]

On 1/29/2021 at 7:44 AM, Spancho said:

The LS244 is indeed only soldered to cut of legs, so there is nothing below.

The legs look more like socket pins, as if the plastic shell of the socket has been removed.

[+Spancho]

4 hours ago, BillC said:

The legs look more like socket pins, as if the plastic shell of the socket has been removed.

Yes in deed they look very much like socket pins. I had the same impression.

I hadn’t had time yet to reassemble the 400. Will do that most likely tomorrow.

[+Spancho]

So I finally found time to test the 400.

The good news is that it is running, except the keyboard the first row doesn’t work. I replaced it with another one I have.

But regarding the memory card ?FRE(0) states only 13326, so I guess it sees only 24Kib.

 

I am not sure if I can test with a known good 48Kib card, due to the different wiring soldered to the main board.

I don’t want to damage the card.

On the memory card I checked already with a DMM for shorts, especially on the vias which had been repaired before.

Any ideas what I can test to narrow down the issue?

 

[+DrVenkman]

36 minutes ago, Spancho said:

But regarding the memory card ?FRE(0) states only 13326, so I guess it sees only 24Kib.

That’s normal for a 16K 400. 

[+Spancho]

1 hour ago, DrVenkman said:

That’s normal for a 16K 400. 

Hm, so only a quarter or third of the card is accessible.

I wonder if that is due to a bad IC or or a bad soldering.

 

Should I test a known good card with the current wiring?

[ClausB]

Hmm, something wrong there. Even without the extra wires on the motherboard it should come up with 32K.

 

If you want to plug an Atari 16K board in there for testing, then disconnect the gray wire first.

[+Spancho]

51 minutes ago, ClausB said:

Hmm, something wrong there. Even without the extra wires on the motherboard it should come up with 32K.

 

If you want to plug an Atari 16K board in there for testing, then disconnect the gray wire first.

I can test with another 48K board. I have to look through my stuff if I have 16K board without case.

Do I have to disconnect any wire if I want to try the 48K board?

[+MrFish]

@Spancho

Although the discussion regarding your Atari 400 and memory board(s) is rather interesting, I think it's a bad idea to turn this thread into a personal troubleshooting documentary. The main idea for this thread is to have 400/800 memory cards pictured and their associated documentation posted.

 

I think a better idea would be to start a new thread and continue your discussion there.

 

From the threads initial post:

Does anyone else have 400/800 commercial documentation that they can scan and contribute to the community? Also, pictures of the live modules would be nice for the record as well... Any help is greatly appreciated.
 

[cornchip]

11 hours ago, Spancho said:

So I finally found time to test the 400.

The good news is that it is running, except the keyboard the first row doesn’t work. I replaced it with another one I have.

But regarding the memory card ?FRE(0) states only 13326, so I guess it sees only 24Kib.

 

I am not sure if I can test with a known good 48Kib card, due to the different wiring soldered to the main board.

I don’t want to damage the card.

On the memory card I checked already with a DMM for shorts, especially on the vias which had been repaired before.

Any ideas what I can test to narrow down the issue?

 

 

I've noticed these BKey keyboards don't seem to be that reliable as time goes on. Having a faulty connect in a single key can lead to a missing row in the matrix. I've found this so annoying that I'm considering a project to create something I dub the 'reBKey A400' utilizing the original keycaps . I have it drawn in CAD, and have yet to mill the PCB.....so hold onto that dead BKey (or maybe sell?). BTW....if anybody should happen to read this, I'm looking for a "1 key' that is missing on my BKey. Anybody?

 

 

 

 

[ClausB]

1 hour ago, MrFish said:

I think a better idea would be to start a new thread and continue your discussion there.

Sorry, agreed.

 

One more thing about the Btari board though: Its design is so similar to the Atari 48K board it's tempting to think it's a copy. But could the Btari have come first? Could Atari have bought the design? The Btari looks prototypish to me, so I wonder.

[+MrFish]

8 hours ago, ClausB said:

Sorry, agreed.

 

Not a big deal. Off-Topic is to be expected, and often desirable.

 

8 hours ago, ClausB said:

One more thing about the Btari board though: Its design is so similar to the Atari 48K board it's tempting to think it's a copy. But could the Btari have come first? Could Atari have bought the design? The Btari looks prototypish to me, so I wonder.

 

Interesting, and maybe possible. 

 

[+MrFish]

8 hours ago, cornchip said:

 

I've noticed these BKey keyboards don't seem to be that reliable as time goes on. Having a faulty connect in a single key can lead to a missing row in the matrix. I've found this so annoying that I'm considering a project to create something I dub the 'reBKey A400' utilizing the original keycaps . I have it drawn in CAD, and have yet to mill the PCB.....so hold onto that dead BKey (or maybe sell?). BTW....if anybody should happen to read this, I'm looking for a "1 key' that is missing on my BKey. Anybody?

 

 

 

 

 

Any 400 keyboard replacement would have some backing/interest from the community, I'm sure. The B-Key was pretty popular.

 

Edited February 3, 2021 by MrFish

[ClausB]

Austin Franklin made a 32/48K board for the 800/400. Here's their flyer and a link to photos:

 

[ClausB]

Intec made at least two versions of 48K:

 

[ClausB]

Intec made at least two versions of 32K:

 

[+kheller2]

Here are pics of my Austin Franklin 400 board. I have no instructions so this is how it was wired on the 400 I purchased. 
 

Franklin (red) vs Atari’s 48k board:
 

 

 

[+MrFish]

Cool... clean looking board.

 

What are all those colored dots on the front? It looks like someone was starting a game of MasterMind.

 

Edited February 7, 2021 by MrFish

[ClausB]

An unusual 48K mod kit from Mosaic:

 

[+MrFish]

1 hour ago, ClausB said:

An unusual 48K mod kit from Mosaic:

 

Thanks... cool thread.

 

[+slx]

I found this in friend's PAL 400, so no documentation. Forgot to take a picture of the rear and added wires on the board.

Brand/marking seems to read "TEP".

I don't think I saw it on this thread yet. 

If I read the chip markings (MCM6665AP15) correctly, it's 64K, but the machine is not ready, so I haven't checked whether it has RAM at $C000. Maybe @ClausB can tell from simply looking at it.

 

[ClausB]

LOL, yes, I think I can! You are right, those are 64K RAM chips, and the other chips are the same as those on the Atari 48K board. More than 48K would require more than the usual 4 wires from the motherboard, however.

[ClausB]

On 2/19/2021 at 2:58 PM, ClausB said:

More than 48K would require more than the usual 4 wires from the motherboard, however.

Correction: it could be done if the 4 wires are A15, A14, RD5, and RD4.

[ClausB]

No soldering 48K for the 400 from Axlon:

My best guess for the cartridge board is just a diode between S5 and S4.

[rchennau]

On 2/2/2021 at 5:55 PM, cornchip said:

 

I've noticed these BKey keyboards don't seem to be that reliable as time goes on. Having a faulty connect in a single key can lead to a missing row in the matrix. I've found this so annoying that I'm considering a project to create something I dub the 'reBKey A400' utilizing the original keycaps . I have it drawn in CAD, and have yet to mill the PCB.....so hold onto that dead BKey (or maybe sell?). BTW....if anybody should happen to read this, I'm looking for a "1 key' that is missing on my BKey. Anybody?

 

 

 

 

If you do count me as a buyer.  My B-Key just died.