RAMKEEPER

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RAMKEEPER

Hi all,

I recently acquired a RAMKEEPER for an Apple IIgs. It came without the external power supply (wall wart) or the gel-cell battery. I'm wondering if I can use a generic wall wart to power the board when the IIgs is powered down. Would anyone have the specs for it? There's a photo of one in the online documentation but the specs are unreadable. Thanks in advance!

Cheers,
Andy

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Much better PDF's can be

Much better PDF's can be found here http://ae.applearchives.com/apple_iigs/ramkeeper/. Anyway here's the specs

IMAGE(https://i.imgur.com/OyhfBEC.png)

So look for a wall wart that is at least 9v dc or at max 10v dc with the jack wired as this IMAGE(https://itp.nyu.edu/archive/physcomp-spring2014/uploads/power_supply_polarity_02.jpg), this picture should be on the power supply, and I'm pretty sure you need the battery for the card, its most-likely used as a power supply filter.

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Battery for AE Ramkeeper, What size and Polarity plug?

I just bought one, and wanted to try to build a Gel Cell battery for it.

Does anyone have one they can measure the plug end? I need the size and Polarity of the DC plug.

ALso, would NiMh  work as well?  Any other suggestions?

 

 

 

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On the battery connector the

On the battery connector the positive is on the card side and the negative is on the edge side

Don't know about charging other batteries, I've only ever used the gel cell

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Ramkeeper will only work on one version of a IIgs: Rom1 or ROM3

A Ramkeeper will only work on one version of a IIgs, either a ROM 1, or a ROM 3, depending on which version of an IC is installed at a specific location:

but the documentation shipped with the card is not clear on which goes with which!

From the Ram Keeper Modification for Apple IIGS 1 Meg (Rev. 3 Motherboard) pdf:

Because of the new board layout of Apple's new IlGS 1 Meg (Rev. 3 motherboard), we've had to modify a chip on the RamKeeper.

If you have Apple's new lIGS 1 Meg, the RamKeeper in this package is ready to be installed.

If you have the earlier IIGS, the RamKeeper per requires a single chip swap to work. 

Rev 3 IIGS Motherboards have 8 1Mb memory ehips, 2 ROMs next to CPU

If you have the earlier CS, substitute the 74F27 chip shown below.

Then there's a photo of the mod'd IC:

That seems to say the mod'd IC above goes with the ROM1 machine, but

I cannot determine which Apple IIgs needs this Mod'd IC, and which just uses a plain SN74F27N IC.

My ROM3 doesn't work with the Plain IC, but it may just be defective.

I'm waiting on another 9.5V 1A neg tip ac adapter since my dog ate the 1st one, and an 8V battery like this one:

https://www.partssource.com/parts/icu-medical-inc/83003650905?pspn=ps96kantlcp

The two power jack center pins share a grounded copper foil trace, so definately center pin negative.

It looks like a 5.5mm X 2.5mm, and it definately has a little larger center pin than the transformer jack, which is a 5.5mm X 2.1mm.

Do you have to hook up the transformer for the board to be recognized or work?

I will try and see if I can get my Rom1 machine up and running to test it with that setup and post the results here.

 

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NOR gates

The modification ties the 2A, 2C, and 3B input pins of the SN74F27N to ground. This could be necessary, for example, if the active-low signals routed to those pins were missing on the IIgs. Without a schematic for the Ramkeeper, I don't know the function of those NOR gates.

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The moded IC is for the ROM 3

The moded IC is for the ROM 3.

I have several ramkeepers with the plain IC that work with the ROM 1 but not the ROM 3

The ramkeeper doesn’t need external power to function

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