I can think at least on two good reasons to have 1MB of Ram on the EP:

First, because the amazing SymbOS can manage all that memory.

And second, because there has always been the challenge of knowing if it would be possible for EXOS to reach the maximum of 4MB of addressable memory that was promised....

Now I can open it up and have a go at doing the internal upgrades, and so test if the new memory board design actually works.

Finally ...

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Yes, it works!

The case fits back together easily too, and there are no problems with the EXP1 cable.


But unfortunely, now I can't figure out how to get the flimsy mylar keyboard connectors back inside the sockets on the motherboard, and so I have no way to run the Advanced test on the memory ... or do anything else at all.

Does anyone have any tips on how to get those connectors into the sockets?

Looks coll
Do you mean the thin keyboard foil back into the connector?
I did it years ago some times, and i took the foil to the top of the connector, and gently pushed down by hand millimeter by millimeter, my fingers were as close to the connector as possible always.

Somebody has cut that strip.

Just the point gets crackled on time, and a way to recover the membrane is to cut some millimetres.

You must grip a strip with the two hands, two fingers each(thumb and index), very near of the tip. Then position the strip on its place and press down firmly on the connector.

I did it years ago some times, and i took the foil to the top of the connector, and gently pushed down by hand millimeter by millimeter, my fingers were as close to the connector as possible always.

Thank you both for the help, I managed to get the cable inserted, and the keyboard works again!

Get a new mylar. They are way better!

Yes, that sounds like a very good idea!

But unfortunely, now I can't figure out how to get the flimsy mylar keyboard connectors back inside the sockets on the motherboard, and so I have no way to run the Advanced test on the memory ... or do anything else at all.

I have now run the "Advanced" test in EXOS 2.4, and can confirm that the board design is working properly.

The 512KB of SRAM shows up as expected in banks $C0-$C3, $C8-$CB, $D0-$D3, $D8-$DB, $E0-$E3, $E8-$EB, $F0-$F3 and $F8-$FB.


I have another 8 spare memory boards available if anyone wants one, and it looks like 1 of those is already committed.

There are a couple of points for anyone to consider ...

1) I live in the USA, and international shipping from here to Europe costs more than the board itself.

2) Since this is a self-assembly project that requires soldering, I really can't provide any warranty on the boards ... you would take the same risk of a manufacturing failure (unlikely), or a user-installation error (way more likely) that I did.

Anyway, you really don't want me to solder the headers onto each board to test it ... my soldering skills are pretty terrible these days, and I did a very messy job on the board that I installed in my own EP64.


On the positive side, because I am just trying to recoup the cost for parts and manufacturing, each 512KB board (including all of the headers and the cable for EXP1 and EXP2) is pretty cheap ... $12.50 USD (approx 3,900 HUF) + postage and packing.


Is anyone interested?

The 512KB of SRAM shows up as expected in banks $C0-$C3, $C8-$CB, $D0-$D3, $D8-$DB, $E0-$E3, $E8-$EB, $F0-$F3 and $F8-$FB.

Nice!

I have another 8 spare memory boards available if anyone wants one, and it looks like 1 of those is already committed.

I would definitely be interested in one. Are these the bare boards or are the surface mount components attached? My soldering skills are probably not up to soldering surface mount components.

The 512KB of SRAM shows up as expected in banks $C0-$C3, $C8-$CB, $D0-$D3, $D8-$DB, $E0-$E3, $E8-$EB, $F0-$F3 and $F8-$FB.

My board is currently using: 
first chip: $DC-$DF, $E0-$EF and $F0-$FB 
the optional 2nd chip:  $BC-$BF, $C0-$CF, $D0-$DB
I tried to create contiguous memory. Is this the wrong approach and should I change the address range?

The ROM programs should be in banks with numbers x0-x3 hex.
It's good to leave room for them.