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-   -   Building the 500+ using the replica mobo (http://eab.abime.net/showthread.php?t=105506)

Vendest 22 January 2021 08:27

Building the 500+ using the replica mobo
Hi, I am new to the Amiga scene and started off by building a new Amiga 500+ and of course my question with revolve around seeking support for troubleshooting :)

The picture of the motherboard with all the components installed https://imgur.com/hhUTtvg

I did not solder any of the jumpers as I do not know what they are for aside from the DFO set to internal.
Tried with 3 different kickstart 1.3, 2.04, 3.14

There was a green screen at first boot which seems to indicate a problem with the chip ram.
I swapped couples of rams and made sure the Fat Agnus is well positioned in the socket.
I couldn't get pass that screen so I reduced the number of ram chips to make it 512kb.
After checking the solder joints for each socket and resitting the chips a new screen came up with "Not enough memory"


I thought I might be on the right path but now I only get a yellow screen directly after boot or changing from a green screen.

What else have I tried? swapped couples of the original chips that I could spare such as both CIAs, Paula, Denise, CPU.
I do not have a spare Agnus or Gary to try.
Most chips are warm by touch aside from the ram chips and Gary which remain cold.
I do have spare logic gates that I could swap but have not tried that yet.

Any suggestions on what I could try next?


shaf 22 January 2021 22:14

what are the jumpers set to?

Vendest 23 January 2021 08:57


Originally Posted by shaf (Post 1455914)
what are the jumpers set to?

I did not set any jumpers aside from the DFO.

After battling for 2 days I was able to make it work!
The ram I purchased on Ali Express was not working at all, replaced it with the "Amiga 500 chip ram replacement board"
I also swapped the 68k CPU. Cleared both green and yellow screen.


When running sysinfo only 512kb is detected instead of 1mb :confused


Shadowfire 19 February 2021 14:05

It is likely that you have a 512k agnus installed. IIRC Agnus is mapped to control all memory access from $000000-$1FFFFF, and if you have an original 512k chip, the 68000 can't see the ram above 512k if its mapped into that address space.
On older machines, the memory above 512k was mapped to $C00000. This is what Kickstart understands, and it puts the memory into the proper (non-chip) memory pool.

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