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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Lurch on March 23, 2011, 05:41:47 AM
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Supposed to give 2MB Fast RAM for the Amiga 500, the mainboard connects to the trapdoor and the adapter connects to the Gary slot.
Have connected it all up but it is only seeing 512KB (1MB total including the 512KB on the a500), is there something I'm missing? The connecting wire is attached, there is a jumper on the mainboard I've tried this off and on.
I don't need to do the mem hack to A500, was thinking that would be only for chip ram?
http://amiga.resource.cx/exp/neuroth502
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I think you need to run a command to add the memory. On the adram and baseboard ram board that use the same kinda of expansion method require software to get the extra memory working. The Adram can see some of the ram without it and the baseboard requires a PAL upgrade (a chip, not the screen mode) if you have a 1 meg agnus to see any ranger fastram at boot otherwise it is only 512k.
That board MIGHT not see any until you run a command to address and add the ram to the system.
Try the baseboard software that adds the ram to the system at this link.
http://amiga.resource.cx/exp/baseboard
Just an idea.
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Hmm I've got a 1 Meg Angus installed, it only sees 512KB of the RAM on the mega 2/8. Will have a look at the baseboard software.
Have checked the RAM on the mega 2/8 and it's fully populated.
Thanks for the info, time for another play :-)
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So you see 512k on the MB and 512k on the expansion board for a total of 1 meg of chip and nothing more?
That is what the baseboard does as well without the PAL upgrade and no software command.
The Adram supports more autoconfig ram with 1 meg agnus but still needs software to see the last 2 megs.
I think the software is generic for this application. I think if the baseboard software does not work then you can use a workbench command that adds ram but I dont remember the command or the syntax.
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Says 1 meg angus so should that mean I see 1 MB from the ram addon?
Will find out when I try that software. Might do a google to see if I can track down workbench command.
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So avail show 1 meg of chip ram?
Unless you have a A500+ the amiga has 512k of ram on the MB. Some of the later a500s had space for 512 more but it was un-populated.
With a 1 meg agnus (8327A) you need to cut a jumper on JP2 to get the Agnus to see more than 512k of chip ram.
With an Adram and Baseboard (similar devices) you would have to run a wire from the cut JP2 (located on the left side of the 68k) to the Gary daughterboard to see ram with 1 meg of chip. I would imagine yours would be the same.
http://www.l8r.net/technical/t-agnus-installation.shtml
I am guessing you have 512k of chip and 512k of fake fast (ranger memory) aka fast ram that is on the bottom expansion slot of the A500. They call it fake fast since it has to be accesses by the CPU via the custom chips and this is as slow as chip ram.
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I've got the expansion in the trapdoor slot with 2MB fast ram on that board but it's only seeing 512KB of that board.
Was thinking the RAM mod was for 1MB or more chip RAM not fast?
The A500 has a 1 Meg Angus. So I'll have to mod Jp2 and work out where to connect a wire to the Gary addon board to see the 2MB fast RAM?
There wasn't another wire with it other than the one that connects the gary addon to the trapdoor card.
Found some Workbench commands here:
http://winuaehelp.back2roots.org/background/amigados.htm
But nothing about RAM.
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No.
NORMALLY with these type of expansions EVEN with a 1 meg agnus you will not see 1 meg of CHIP ram without the JP2 mod.
When you do that MOD with these types of expansions they allow you to ONLY see 1 meg of chip (512k on the board and 512k on the expansion board). To see more ram you have to run a software command. The Adram540 will let you see another 1 meg of fast ram in addition to the chip ram. The baseboard requires a PAL upgrade to see some more fast ram and software to see all of it.
If you dont have the 1meg CHIP ram mod done and you have one of these expansion you will ONLY see 512k chip ram and 512k fake fast from the expansion board.
When you run the software command the other fast ram is seen.
See this thread.
http://www.amiga.org/forums/showthread.php?p=572103
That is why I was asking if you actually had 1 meg of chip ram or just the 1 meg agnus.
You want to buy a Adram 540?
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I think the software is generic for this application. I think if the baseboard software does not work then you can use a workbench command that adds ram but I dont remember the command or the syntax.
I had a 1.5mb trapdoor expansion that connected to gary and required no software to work. I was probably on kickstart 1.3 at the time & I'm pretty sure the memory sizing in kickstart can cope with >512k at c00000.
Commands to add memory are usually only required for non auto config memory in the fastmem part of the address map. It might be mapped there, although I don't see why they wouldn't have connected to the CPU slot and gotten proper fast memory. You're having to open the case up anyway.
The extra memory might be disabled somehow, if it needs software to wake up the board then it'll be specific to that board. It might not be hooked up to gary correctly either. I used to have terrible problems with reliability as I also had a 2mb agnus with onboard memory that also hooked up to gary. Yes I probably should have bought an a500+.
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It can be done autconfig for some of the memory in the ranger address space but the two board I know and have personally used (Adram and Baseboard) REQUIRE software to get all the ram working AND or required hardware updated to get more memory working once a 1 meg of chip ram mod was done.
You can read the baseboard and adram docs. The way the ram is enabled is only related to the address space of the ram. If it is addressed in the same area then the software might work.
The board that lurch has does not have any docs online or software online that I can see. I am giving my best guesses to help him out. If we had docs for the board then we could make better guesses.
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Hmm, going to start simple. Checking the gary adapter make sure thats all okay but will start there as going by what I've read it should autoconfigure, well atleast to 1.8MB.
Also with the chip ram mod doesn't that disable the trapdoor?
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Well after trying just about everything, and even comparing the setup I have with the pictures on the amiga hardware databse for the card it's still only seeing 512kb.
So guess I'll just use it as a 512kb card for now ;-)
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Well after all that tried it on another A500 (both 6a boards) and it works fine. 2MB, well 2.5 including the onboard RAM.
So it was the board limiting it to 512KB. :-)