Emax

Each of the Samsung chips is 256k x 4 bits. So two of them give you 256kB and 8 x 256kB = 2MB.

The 18 pin sockets are for the 4464 DRAM used in the 1MB version of the Emax II and you cannot use them at the same time as the 20 pin sockets, its 
either one set of DRAMs or the other. If you want to expand your Emax II to more than 2MB you will need to get the RAM expansion board...

/Tristan

Monday, November 30, 2009, 7:59:55 AM, you wrote:

>
  
So I opened up the cover again and did some thorough examination.

I have 16 chips of Samsung KM44C256CP-7 up through IC socket 63. At 256k per chip I don't initially understand why that only equals 2MB of 
memory...

Sockets 64-99 are available for soldering, but they are 18 pin slots compared to the 20 pin Samsungs! What is up with that?

I shone a light onto the PC board and it seems all of the traces on two sides of the processor go through the respective chip sockets all the way to the 
two expansion board connectors, so that is hopeful that once it can be figured out, we can make our own expansion boards right on the mainboard.

If we can find the right source for 18 pin IC sockets and the right 44256 memory modules (70ns,20ns,130ns) I should be able to upgrade my Emax to 
6mb of memory right on the mainboard.

--- In emax@yahoogroups.com, "thenewyorkcowboy" <thenewyorkcowboy@...> wrote:
>
> Ah! I finally figured it out. I did more research and my model, the 2212 is only a 2mb which I verified by Master 4,Y,2, and got 1048488. Here I had 
been doing improper math but with the Emax II Diagnostics.pdf I came to this conclusion. Bad for me! But now I need to find someone that has a late 
model 2205 with 8mb and find out if the factory installed all the memory on the mainboard or did they also use two 2208 kits to get to 8mb. That would 
provide the solution whether or not the mainboard slots could be populated with sockets and chips.
> 
> --- In emax@yahoogroups.com, "Everett" <evy_newt@> wrote:
> >
> > My expanded EMAX actually only has a portion of the sockets filled on the main board. I believe the writeup on emulator archive goes through why 
in more detail. I believe someone else stated that the PALs are different on the models with the board installed. The upgrade kit inventory shows these 
PAL chips in there, so that makes sense.
> > 
> > --- In emax@yahoogroups.com, "thenewyorkcowboy" <thenewyorkcowboy@> wrote:
> > >
> > > Yeah I was all hopeful until I opened my Emax II up and saw that I don't have the board, just an empty space where it looks like there are 
enough places to solder in sockets to get the Emax II up to 12 megs. I have 4 already (16 chips) and there are 32 spaces available. Does anyone think 
that actually soldering in another 16 sockets would be the same as adding an expansion board?
> > > 
> > > --- In emax@yahoogroups.com, Ted Summers <djtbs1@> wrote:
> > > >
> > > > I believe what the Memory Upgrade people are saying is:
> > > > 
> > > > 1) If you have "scrambled megs" and your emax 2 doesn't see all your 
> > > > memory, then they have a fix
> > > > 2) If you have a expansion board, and it is not full, you now have an 
> > > > inexpensive way to fill it up the rest of the way and get a chip so 
> > > > emax2 sees the added memory now.
> > > > 
> > > > But I don't think they are saying they are duplicating the Expansion 
> > > > board at all.... you must already have an expansion board.
> > > > 
> > > > 
> > > > 
> > > > On Nov 26, 2009, at 6:36 PM, Reinaldo wrote:
> > > > 
> > > > So...
> > > > 
> > > > I can download the file and burn a new eprom chip for my emax II.
> > > > 
> > > > Then I can buy the memory chips on eBay.
> > > > 
> > > > But I need the expansion board!
> > > > 
> > > > How do I do without expansion board then?
> > > > 
> > > > 
> > > > 
> > > > 
> > > > 
> > > > 
> > > > [Non-text portions of this message have been removed]
> > > >
> > >
> >
>