Double module diy - question

[Karel]

Hello,

I would like to merge this two modules into one shell. Searching for some info about how to wire the modules together I found the Cristoph Klug PDF about constructing double X-Memory module.
Double X-Memory module

Nowhere I found any info about how to wire together two different modules like for example X-Functions and X-Memory or if it is even possible.

I am grateful for any info / pointer in the right direction.

Thank you very much!

Karel

[MeindertKuipers]

Hello Karel,

Creating a double module can be tricky depending on the module type. Almost all modules are port addressed, meaning that the base address of the software of the module is derived from the port they are plugged into. This is achieved using the B3 and B4 lines (see the document you linked to). These lines are hardwired to 0 or 1 depending on the port:

Code:


B4 B3 Port Decoded Address Range 
 0  0   1    $8000-$9FFF 
 0  1   2    $A000-$BFFF 
 1  0   3    $C000-$DFFF 
 1  1   4    $E000-$FFFF

Extended Memory modules use this in a different way. Seperate XMEM modules must NOT be plugged above each other in a port, and they do not take up a page from the address space above (but the Extended Function module does!). The XMEM modules use the B3 line only

For any other modules you must consider in which port it should be plugged, even when doubled and plugged in another port. But the port you have reserved for a doubled module can not be used for any other module. So nothing much is gained. IMHO doubling modules does not make much sense except for XMEM modules.

In the good old days I once made a triple module with the Extended functions and 2 XMEM modules, plus a small capacitor to keep the content when moving the module to another calculator. But this required cutting the shell to make space.

Beter solutions are coming: the MAXX module and a not yet officially anounced product that will give you all the memory you will ever need.

[floppy]

When I bought a Nov64d module at Diego clonix41@gmail.com , I sent him 2x XMEM, then he sent back one double-XMEM and one Nov64d (I am not good in soldering; he is). Looks like he could use the spare module housing.

[Karel]

Thank you both!

I somehow missed the MAXX module info. Now, I can hardly wait for it. :-D

Regarding the empty modules - I know there is shortage of empty shells. I wonder if company like jlpcb could make a batch of bare pins for the modules and then the shells could be 3d printed.