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.
It looks like over 30 EP64's have been sold by the Egyptian sellers on eBay recently, but I can't see anywhere near that many new users here.
I'll put you down for one of the boards!
![Smiley :)](/Smileys/phpbb/smiley.gif)
Once I've sold my spares, I'll release the design files and final JLCPCB manufacturer-approved Gerbers so that anyone can place another order for more ... they were an easy company to deal with and their board quality and SMT manufacturing seems excellent (to me), and very affordable.
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 surface mount (SMT) compnents were all factory (i.e. robot) installed by the board manufacturer ... that is why I wanted to create a simple single-sided board design. I certainly couldn't solder those small components myself either!
![Wink ;)](/Smileys/phpbb/ds_icon_wink.gif)
The two 0.1" headers male headers for EXP1 and EXP2 do still need to be soldered onto each SRAM board by the purchaser.
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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.
Keeping the memory contiguous might be the best for anyone that wants to maximize their Enterprise with external modules ... but what I have done doesn't seem like it would cause a problem in practice with any of the expansion hardware designs that currently exist (including the Symbiface3).
The simple 74HCT138 decoding scheme that I have used can fit up to 2.5MB of RAM into the Enterprise's address space, with 2MB of that being contiguous.
Using a GAL/CPLD/FPGA for decoding definitely allows more flexibility, but I think that it is worth pointing out that the Enterprise's designers expected discontiguous blocks of 64KB RAM memory ... the original
external 64KB expansion module was mapped into one of six different 512k regions of address space, resulting in a maximum of 384KB+128KB of RAM on a fully-expanded Enterprise.
Now, it might not be too difficult to extend what I have done and make a 1.5MB internal RAM expansion board, which could then use an external Symbiface3 to give a full 4MB of memory (3.5MB RAM and 0.5MB ROM) ... but how many people would really want such a board?