A500 1MB chipram mod

[TroelsDK]

Hey Gurus!

I'm planning on doing the 1mb chipram mod to one of my 500s

Rev6a



and following this guide:

http://dl.dropbox.com/u/71121999/Amiga/Xform-A500.pdf

I have some ½mb ram boards lying around, but I have no idea whether the ram chips are usable for this mod.

Here is the one I'm most willing to destroy as it is a pain jamming in on the expansion anyway.


Are these chips OK for this?

Thanks in advance!

 

[NMI]

Yes, those chips will be perfect for the mod.

But are you planning to "convert" the expansion port to chip ram as detailed in the article or solder those ram chips to the moterboard?

Not that it really matters, they will work in both mods.

There is an excellent thread here at Amibay detailing both mods:
https://www.amibay.com/showthread.php?t=4722

http://https://www.amibay.com/showthread.php?t=4722&highlight=a500+chip+hack

 

[TroelsDK]

Thanks

Yes I was planning to solder them on the board

Link is broken

 

[NMI]

Link is broken

Link fixed.

 

[Zetr0]

@TroelsDK

Have a read of this thread I posted this thread about two and a half years ago... wow... thats a long while back.... didn't realize it was that old!

anyway, it describes all the steps needed to modify the Rev 6A A500 for 1MB of CHIP RAM =)

 

[TroelsDK]

What started of as a simple altercation turned in to a real sticky situation...

Thats 1, 3 to go...


2 more went great, but 4th one broke of...



Well I am determined to get it done, so found another ½mb card, and discovered that the ram in that one wasn't soldered in... Great!

But before I continue, I'll have to check with you guys that these will do just fine for this "simple" project



Someone give a an OK, and I'll continue with this

 

[rkauer]

Check the datasheet of the chips you salvaged and compare with the ones you have in the Amiga.

The speed must be 120ns or better. Prefer 80ns and faster for reliable operation.

 

[TroelsDK]

Thanks, but I have no idea how to found out...

This is the board they came from:



And these are the chips on the motherboard:

 

[rkauer]

Totally compatible.

 

[Zetr0]

Totally compatible.

+1!

The installed A500 Rv6A are Panasonic 256x4 - 80ns

The ones salvaged from the care Motorola 256x4 - 80ns

I suspect the only problem you will have is the brands not matching (thats to say... thats not a problem lol!)


Overview of the Mod



With Jumper location JP2 (cut and soldered)



with Jumper location JP7A (trace cut)


that should see you good =)


BTW, it matters not if you use a 512KB expansion card or solder chips to the motherboard, after this modification it will string up 1MB of CHIP RAM, for a friend of mine I did actually make this modification switch-able such that he had the following options

512KB CHIP
512KB CHIP 512KB OTHER
1MB CHIP

and then he upgraded to an A500+..... typical.

 

[rkauer]

But hacking the board to have the physical 1Mb can open one option: one can hack another 512kb RANGER RAM into the A500 using a small DIY board.

1Mb chip RAM + 512kb RANGER.

Win-win situation.

 

[TroelsDK]

Sounds awesome guys, I'll continue with this in the afternoon then

 

[NMI]

2 more went great, but 4th one broke of...

You can save that 4th chip by carving away some of the plastic above and below where the pin broke off. That way you can expose enough metal to be able to solder a short lead to the MB.

@rkauer.
Adding a delay line like that sure don't feel right to me.
But I'll have to wait until my cheap Chinese logic analyzer arrives before I can verify it...

 

[TroelsDK]

That forth chip is already in the trash, but if anyone wants those three leftovers I'll be happy to send them to you

 

[NMI]

NOOOOO!!!!!

Sending PM regarding the other 3 chips.

 

[TroelsDK]

No more help needed (Can you picture me dancing and shouting of joy?)

I'll continue this in the photo booth

Thanks guys! And leftover ram and board is on it's way to NMI

 

[krisbA]

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