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Old 30 September 2022, 16:26   #1
MartinCummings
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Using GottaGofastRAM with A590

Hi

I'm thinking about buying a GottaGoFastRAM 8MB plugin for my A500+. My questions are, will it coexist with my A590 with 2MB Fast Ram and trapdoor expansion installed which gives me 2MB Chip Ram? Also, will I need to connect up the autocfg connections, if so, where do I connect them?

I'm hoping that this combination will give me 12MB total RAM.

Thanks for any help.
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Old 30 September 2022, 16:39   #2
alexh
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Quote:
Originally Posted by MartinCummings View Post
will it [a GottaGoFastRAM 8MB] coexist with my A590 with 2MB Fast Ram
No. The A590 and GottaGoFastRAM share the same address space.

http://oscomp.hu/depot/amiga_memory_map.html

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Originally Posted by MartinCummings View Post
I'm hoping that this combination will give me 12MB total RAM.
The maximum amount of FastRAM you can have with a 68000 is 8MB
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Old 30 September 2022, 17:10   #3
MartinCummings
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Originally Posted by alexh View Post
No. The A590 and GottaGoFastRAM share the same address space.

http://oscomp.hu/depot/amiga_memory_map.html


The maximum amount of FastRAM you can have with a 68000 is 8MB
Thank you. I'm glad I asked first.
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Old 30 September 2022, 17:43   #4
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If you took the RAM out of the A590 it would probably work and give 2+8MB
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Old 30 September 2022, 18:30   #5
LIV2
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You can hook the a590s config out pin to the gottagofastram's cfgin pin, or if you're using kickstart 2 or higher you can flash the "snoopy" firmware which will allow them to coexist without this wire. You can get it here: https://github.com/LIV2/GottaGoFastRAM/tree/snoopy

It works by watching for autoconfig cycles then only answers when it sees that no other device is talking
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Old 01 October 2022, 00:52   #6
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Originally Posted by LIV2 View Post
You can hook the a590s config out pin to the gottagofastram's cfgin pin, or if you're using kickstart 2 or higher you can flash the "snoopy" firmware which will allow them to coexist without this wire.
Is this necessary for an A590 with no RAM fitted?

Is there a disk DMA performance advantage having 2MB fitted to the A590?

I don't think any autoconfig setup is going to get around the 8MByte Zorro II FastRAM maximum.
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Old 01 October 2022, 18:12   #7
LIV2
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The main issue is that the scsi controller part is also an Autoconfig device and will conflict with the GGF because they'll both try to answer the first Autoconfig request.

This is also evident on the CDTV which occupies the first Autoconfig slot with its DMAC - for the CDTV there's a special firmware for the GGF that always ignores the first autoconfig request, but this bodge might not be suitable in this case as it may be desired to run without the A590 sometimes etc.

So the two options for coexistence are:
1: use the snoopy firmware if possible (requires kick 2 or higher)
2: solder a wire from the edge connector's "cfgout" pin and connect it to the GGF's "cfgin" pin - gadgetuk164 shows how to do this here at 23:30 [ Show youtube player ]

The GGF will auto-size to fit with the A590s ram but it's better to disable the A590s ram because the auto-sizing steps are 8-4-2-1MB - with 2MB in the A590 the GGF would only offer 4MB itself giving 6MB total
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