Amiga 500 1MB chip ram mod?

[skintt]

Ey up mi' fellow Amigans!


I recently purchased a stock A500 from ebay and fitted an internal Gotek and a pistorm revb with a raspberry pi 3a+ which works well running emu68.



I recently bought a 512K ram expansion from Amigakit which I've fitted to the expansion slot. I've read about the 1MB chip ram mod and was wondering what advantage this has?


I have checked in Sysinfo and my Agnus chip is reported as "Agnus - 1MB" so I assume I can carry out this mod but I'm not sure what the advantage is.


I have some experience with soldering so I'm moderately comfortable with carrying out physical mods but I want to know if it's worth the 'risk' or not!



Thanks in advance!

[Tajmaster]

Hi,
It's very easy to do on rev 6 motherboards. I have attached an image which shows what to do.

I believe with that particular AmigaKit expansion you don't have to do the JP7A bit?

The advantage is a lot of games will load in extra sounds or do something fancy with the graphics.

Some people say it is better to stick with it as is for compatibility but I have never encountered a game that needed this switching back in 30 years

[skintt]

Originally Posted by Tajmaster

Hi,
It's very easy to do on rev 6 motherboards. I have attached an image which shows what to do.

I believe with that particular AmigaKit expansion you don't have to do the JP7A bit?

Thanks for this, it looks fairly straightforward.

The note which came with the RAM expansion says there's a jumper on the card which will enable the 1MB chip ram mod.

I'll get a sharp knife and warm up the soldering iron!

[alexh]

Originally Posted by skintt

The note which came with the RAM expansion says there's a jumper on the card which will enable the 1MB chip ram mod

I can't think what that is for.

[Nbdy]

You have the PeteAU 2MB expansion, what will add 1MB of CHIP and 1.5MB of slow ram ...

Of course you need an gary adapter ...

If you need one, PM me

[skintt]

Originally Posted by alexh

I can't think what that is for.

The note which came with the board says

"On most Amiga 500 configurations the LK1 jumper should remain covered / closed by default.

On an Amiga 500 motherboard revision 6A equipped with an Agnus 8372A chip, a modification can be applied to enable a full 1MB Chip/Graphics memory. If this motherboard modification has been carried out then the LK1 jumper can be uncovered/opened"

So I assume as Tajmaster refers to, I just have to cut the trace on the lower two pads of JP2 and bridge the upper two pads, then just open the LK1 jumper on the RAM expansion without having to modify JP7A.

[Tajmaster]

Originally Posted by skintt

The note which came with the board says

"On most Amiga 500 configurations the LK1 jumper should remain covered / closed by default.

On an Amiga 500 motherboard revision 6A equipped with an Agnus 8372A chip, a modification can be applied to enable a full 1MB Chip/Graphics memory. If this motherboard modification has been carried out then the LK1 jumper can be uncovered/opened"

So I assume as Tajmaster refers to, I just have to cut the trace on the lower two pads of JP2 and bridge the upper two pads, then just open the LK1 jumper on the RAM expansion without having to modify JP7A.

Yep

[skintt]

Success!

[Tajmaster]

nice one dude

[stx2199]

btw, post a sysinfo screenshot to see how fast is ur A500 with the pistorm+rp3A

[skintt]

Originally Posted by stx2199

btw, post a sysinfo screenshot to see how fast is ur A500 with the pistorm+rp3A

44 x faster than an A4000 apparently!