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Old 10 December 2018, 23:53   #1

E-Penguin's Avatar
Join Date: Jul 2016
Location: Darmstadt
Posts: 856
Using Fast RAM added with AddMem?

Short version - WHDLoad doesn't appear to see Fast ram added via AddMem. "Can't allocate ExpMem". Is this expected?

Long version:
You'll have to bear with me on this while I explain how I got here...

I have a A500+ with an A590 hdd/ram expansion, with 2MB in it. I want to use it for WHDLoad gaming, and I realise it would be better with 4MB fast, or more.

There's a guy on amibay selling 68k-socket RAM expansions, which sort-of support autoconfig but don't support the chaining, so when I try to use one it makes my A590 not work, which rather defeats the whole purpose of trying to get games running from the harddisk.

It's possible to disable the autoconfig on the 68k-socket RAM, and the guy selling them would do me a 4MB version starting at 0x600000, which I could then add with AddMem. I tried to do it myself but got bogged down in not understanding HDL and didn't progress much further.

Before splashing out on new hardware I thought I'd try it in WinUAE. I started up a bog-standard A500+ config, 2Mb Chip, A590+2Mb Chip, and 4Mb non-autoconfig RAM in the Z2 space. AddMem adds the memory and using MemCheck & SysInfo I can see that it is indeed working in that it can be written to / read from.

Only, when I start "The Settlers" slave (latest from retroplay, WHDLoad 18.3) it fails with "Can't allocate ExpMem".

I have tried disabling PRELOAD, and setting ChipExp but neither made any difference.

I wondered if having non-contiguous Fast ram blocks was the issue, but when I move it to 0x200000 (at the end of the A590's autoconfig ram) still doesn't work.

I then wondered if having blocks split across two memory devices was the problem, so I disabled the ram on the A590 entirely and set up the winuae config to have 8Mb non-autoconfig fast which I add through AddMem. No dice - "Can't allocate ExpMem".

I'm left to conclude that WHDLoad can't see/use memory added through the AddMem command.

Any ideas?
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