Amiga.org

Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: stanlong on March 28, 2009, 10:57:05 PM

Title: chip ram A2000
Post by: stanlong on March 28, 2009, 10:57:05 PM

how do we add chip ram to an A2000

Title: Re: chip ram A2000
Post by: Bazzaq on March 28, 2009, 11:16:31 PM

try and get yourself a DKB megachip
DKB Megachip (http://www.amiga-hardware.com/showhardware.cgi?HARDID=992)

Title: Re: chip ram A2000
Post by: save2600 on March 28, 2009, 11:16:35 PM

You need a 3rd party 2MB Chip Ram Adapter by DKB or someone else (make sure it has 1mb memory on it), an 8375 Agnus and you might need to change a jumper setting on your motherboard.

This site as well as Amibay, Softhut and ePay are all good places to find these things.

Title: Re: chip ram A2000
Post by: rkauer on March 28, 2009, 11:35:46 PM

 Depends on the motherboard revision: versions prior to 4.0 are terrible to add a new Agnus.

 for newer boards, just a Megachip, MiniMegiChip or Megichip. Those are boards with the "updated" 8375 Agnus and one more Megabyte on it. Expect to pay around US$100 or more for one of those babies.

 If your board is 6.0 or newer, there is a hack: piggybacking the same memory chips over the original ones, bending one of the address pins, adding a demux inside the Amiga and more important: adding a 8372AB Agnus (the one from the A3000).

 The last Agnus is the only one compatible with the A2000.

Title: Re: chip ram A2000
Post by: stanlong on March 30, 2009, 05:29:47 AM

not sure of the word demux

Quote

rkauer wrote:

 Depends on the motherboard revision: versions prior to 4.0 are terrible to add a new Agnus.

 for newer boards, just a Megachip, MiniMegiChip or Megichip. Those are boards with the "updated" 8375 Agnus and one more Megabyte on it. Expect to pay around US$100 or more for one of those babies.

 If your board is 6.0 or newer, there is a hack: piggybacking the same memory chips over the original ones, bending one of the address pins, adding a demux inside the Amiga and more important: adding a 8372AB Agnus (the one from the A3000).

 The last Agnus is the only one compatible with the A2000.

Title: Re: chip ram A2000
Post by: fiat1100d on March 31, 2009, 10:49:31 AM

Demux = demultiplexer. Usually devices that, given a binary input, select the output related to that number. For example, a 3 to 8 decoder/demultiplexer has 3 bit binary input and thus can select one of eight outputs.

I think the demux is required for managing the additional memory bank.