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!

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!  

The two 0.1" headers male headers for EXP1 and EXP2 do still need to be soldered onto each SRAM board by the purchaser.

[ Guests cannot view attachments ]

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?

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!  

The two 0.1" headers male headers for EXP1 and EXP2 do still need to be soldered onto each SRAM board by the purchaser.

Excellent! Please sign me up for one. I've no problem soldering non-SMT stuff.

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?

Hmmmm

I don't only want to throw words as true: on the emulator or on the real machine, if you have a SD cartridge or a floppy controller you can try this:

-Write a one program line, for example 10 REM.
-Execute LIST to see you program list....
-Execute :EXDOS . This will open you an EXDOS screen where you can for example do a DIR.
-Press the ESC key. The EP will freeze, but if you press once the reset key you are again on Basic.
-Execute LIST.

You can also do the same with the included word processor:
-Execute :WP on the Basic editor. This will open the word processor.
-Write some random text
-Press F8 and execute EXDOS+Enter
-Again the EXDOS screen will open. Make a DIR.
-Press the ESC key. This time the EP has not freezed, and you have returned safely to the text edition.

---------------

Basic itself is multisession, you can edit several programs at the same time, even jump between them while on execution.

-Write this program:
10 TEXT
20 CHAIN 1
-Execute this command: CHAIN 1
-Insert these lines:
10 print "HELLO"
20 CHAIN 0
-Execute this command: CHAIN 0

-You now see a flashing HELLO.

The CHAIN command not only swaps programs, also executes them.

-------

Another proof that the EP is multisession: almost all programs and some games have a clean exit to EXOS:

-Basic has the ":"
-WP has the F8 key
-EXDOS has its prompt.
-Try to search the exit on other languages or utilities, like Hisoft-Pascal, Lisp, Forth, Epdos, EGI, PaintBox, IS-Chess, etc

--------

The main tool to make this possible is an efficient management of memory. Every program will ask EXOS the necessary amount of memory, and at exit they have to free it, returning the memory to EXOS.

Ah, yes... I have only repeated what you pointed some time ago.... but I didn't remember about executing TEXT blindly.

Thanks.

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!

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.


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!  

The two 0.1" headers male headers for EXP1 and EXP2 do still need to be soldered onto each SRAM board by the purchaser.

Thanks, John!

[ Guests cannot view attachments ]

[ Guests cannot view attachments ]

I only have 2 of the 512KB memory expansion boards left, if there is anyone else out that that wants to add some memory to the Enterprise 64 that they recently bought from Egypt or Russia.

Great!

Thanks for being so kindly sharing your work.