A600 8Mb fast expansion

[TjLaZer]

I have been looking for such a product!  You should make it so  it accepts a single 72pin SIMM!  That way the end user can install a 4MB or 8MB SIMM!  I would like to have a 4MB version, that way I can use my PCMCIA port!  If you consider selling a 4MB version let me know, I would buy atleast two!

[rkauer]

 I could be wrong (sometimes I am), but the SIMM itself is merely a little board to held the memory chips.

 So all you have to do is modify a little your board to put a SIMM socket in it. That way the user can choose any SIMM he/she have.

 Or the Altera chip must be "notified" of the size of the bank?

[rkauer]

 BTW: where can I find the schematics to place a 1Mb SIMM in the trapdoor of mine A600?

[alexh]

TjLaZer wrote:
You should make it so  it accepts a single 72pin SIMM!  That way the end user can install a 4MB or 8MB SIMM!

Just installing a smaller SIMM doesn't make it PCMCIA friendly!

[lordv]

Dunno, if I can buy simm sockets here...

[Piru]

@alexh

24-bit = 16Mb

Of which 8MB is available in linear fashion for Autoconfig(TM).

9.5MB would be possible if some of the memory would occupy some other memory areas.

[Piru]

@alexh

I was wondering if you could add a register that when you write a particular value to it, it stops decoding addresses in the upper 4 Mbyte range.

You could then switch on/off the upper 4Mbytes in software.

card.resource checks for existance of the memory at address 0x600000. If any is present, it will not initialize the resource. Thus, even if you could turn off the memory later on, it would not bring PCMCIA back.

If the state would survive a reboot then it would work, naturally.

[rkauer]

 A really bad solution for this issue is put a switch in the upper address line of the memory/SIMM to trick the board as only 4Mb is installed, instead of the full 8Mb.

 The better of two worlds: 4Mb and free PCMCIA port or 8Mb in your A600!

 My only concern is the Altera chip: it needs to "know" previously the size of the memory?

[1NOM155]

nice work.

but one question, instead of welding the ram, cant be more easy use a SIMM sockets? if it possible.

[Evillord68]

Nice work.

[rkauer]

 Doing this you'll have more complexity in the board layout.

 I simply prefer the SIMM header to solder any bank of memory I choose. Even if the SIMM fails, it's easy to swap for other bank (although it have to unsolder the bad first).

[1NOM155]

sorry for double post.

alert:

the button "Cancel Post" doesn't work

[1NOM155]

by rkauer on 2007/12/20 22:27:03

Doing this you'll have more complexity in the board layout.

I simply prefer the SIMM header to solder any bank of memory I choose. Even if the SIMM fails, it's easy to swap for other bank (although it have to unsolder the bad first).

i agree

[Retro_71]

WOW Nice project i wish i can do things like that.  :-D
Can't wait for finally outcome.

[da9000]

Piru wrote:
Of which 8MB is available in linear fashion for Autoconfig(TM).

Can someone elaborate on this? I understand what is meant by linear and Autoconfig, but does it mean that the rest (other  8MB - reserved areas), can't be linear or can't be pooled with the lower 2+4MB ?

Or perhaps it means that because the upper regions (past 10MB) are fragmented due to reserved areas (ROM, etc)

Piru wrote:
9.5MB would be possible if some of the memory would occupy some other memory areas.

So does that mean some could be mapped past $A3FFFF-$FFFFFF?
I assume that's what Piru was hinting at.

[rkauer]

 But then you need to change the Altera chip for a bigger one or even use some kind of "mini" CPU to control the memory chunks.