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Author Topic: Internal memory expansion (Read 122397 times)

Online gflorez

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Re: Internal memory expansion
« Reply #315 on: 2020.October.12. 09:08:55 »
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....

Offline elmer

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Re: Internal memory expansion
« Reply #316 on: 2020.October.14. 05:48:12 »
For no sensible reason, just intellectual curiosity. And my GAL has so many unused outputs. :lol:

Haha ... OK, I get that, cool! :lol:


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.

Yes, that's an excellent reason for those folks that want to maximize SymbOS memory on an Enterprise.


But, there's no Enterprise-specific (i.e. EXOS) software that needs more than 512KB, is there?

Any there many (or any) EXOS programs that need more than 128KB?


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....

Haha ... I can see from your posts that you love to push the Enterprise's hardware expansion as far as it will go. :)

For myself, I am more interested in what I (as a game developer) could have created for the Enterprise if it had been popular enough that I had been told to write a game for it.

So that means that I am focusing on the unexpanded Enterprise 128, and possibly the 6MHz/320KB that were shown in the 911 prototype.

Offline elmer

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Re: Internal memory expansion
« Reply #317 on: 2020.October.14. 06:07:15 »
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 ...

25620-0

25622-1

25624-2

25626-3

Yes, it works! :mrgreen:

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?

Online gflorez

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Re: Internal memory expansion
« Reply #318 on: 2020.October.14. 08:40:09 »
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.

The clue is to take a very short portion of the strip, so it not bends while inserting it.
« Last Edit: 2020.October.14. 15:59:28 by gflorez »

Online geco

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Re: Internal memory expansion
« Reply #319 on: 2020.October.14. 08:41:46 »
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.

Offline Wolfgang

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Re: Internal memory expansion
« Reply #320 on: 2020.October.14. 12:39:35 »


Yes, it works! :mrgreen:

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?
Great! :smt038

It seems that there are at least two versions of the original mylar.
One version has two equally long connectors.
The other version has a short left side connector and a long right side connector. Those are a *bitch* to get in. I always ask my wife (she loves me for this :smt074 ) to hold on to the top of the computer while, I use my most surgical hands to do the operation. :smt027

Get a new mylar. They are way better!

Online gflorez

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Re: Internal memory expansion
« Reply #321 on: 2020.October.14. 16:50:45 »
Somebody has cut that strip.

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

Offline Wolfgang

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Re: Internal memory expansion
« Reply #322 on: 2020.October.14. 17:17:10 »
Somebody has cut that strip.

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

Yes, but it seems this was already done in the factory. I found this to be the case with two out of three unopened EPs.:(

Offline elmer

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Re: Internal memory expansion
« Reply #323 on: 2020.October.15. 22:40:05 »
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! :ds_icon_cheesygrin:


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?
« Last Edit: 2020.October.15. 22:45:28 by elmer »

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Re: Internal memory expansion
« Reply #324 on: 2020.October.16. 08:06:13 »
I would be interest for one in case if remains, i do not want to stole the opportunity from others who really need the expansion.

Online emptiness

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Re: Internal memory expansion
« Reply #325 on: 2020.October.16. 08:48:15 »
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.


Online emptiness

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Re: Internal memory expansion
« Reply #326 on: 2020.October.16. 08:50:28 »
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....

It would be very cool to see an Enterprise with the full 4Mb.  I still need to get my Enterprise motherboard working and wired up with a keyboard, maybe a project for after that...

Offline Wolfgang

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Re: Internal memory expansion
« Reply #327 on: 2020.October.16. 10:00:45 »
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?

Online geco

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Re: Internal memory expansion
« Reply #328 on: 2020.October.16. 10:10:22 »
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?
I think contiguous range is the best way, as i remember i worked with at least 1 program which searches the biggest contiguous memory ranges for use.

Offline pear

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Re: Internal memory expansion
« Reply #329 on: 2020.October.16. 10:13:23 »
The ROM programs should be in banks with numbers x0-x3 hex.
It's good to leave room for them.