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avatar_zhulien

Vortex 512kb Memory Expanision

Started by zhulien, 16:06, 06 March 23

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zhulien

I was reading through the Vortex memory expansion documentation and a couple of things weren't clear.

Can the Vortex memory expansion co-exist with the DkTronics ones without hardware clashes?

Seems the Vortex 512kb expansion can only page in 32kb at a time, either the lower half an upper half 8 lots of 64kb in total - or depending on usage, 8 lots of lower 32kb and 8 lots of upper 32kb.  Can an entire 64kb be paged in at once (i.e. page the lower 32kb, jump to a routine in that lower 32kb, then page the upper 32kb in )? Or by design is it only 32kb at once?

Prodatron

As there is only 1 bit for selecting either the upper or the lower 32K it seems, that you can only map 32K in total at the same time. It also seems, that half of the expanded RAM can only be mapped to #8000 and the other half only to #0000. Strange and limited design.

GRAPHICAL Z80 MULTITASKING OPERATING SYSTEM

zhulien

With my current memory map in MCP, I think I could almost simulate the 2nd 64kb of a 6128 (the top half of each lower 32kb) as long as my code doesn't do anything in the lower 16kb and upper 32kb.  That would give users who only have a Vortex 512kb expansion the ability to run 4 x 16kb background tasks just like someone with a CPC 6128.  Then likely the only useful thing I could use the rest of the RAM for is RAMdisc, or datastorage.  Yes, very limited - is there enough owners of them to justify supporting it who didn't already buy a more flexible memory expansion?

SerErris

Quote from: zhulien on 16:06, 06 March 23Can the Vortex memory expansion co-exist with the DkTronics ones without hardware clashes?
It cannot run in coexistence with a DkTronics. It uses the same ports (e.g. it claims to be DKTronics compatible).

From this document, it looks like the 512k version (and only that) it can page out the whole memory:
https://www.cpcwiki.eu/imgs/b/bf/Vortex_Ext_SPM_-_Memory_mapping_%28DEU%29.pdf


Proud owner of 2 Schneider CPC 464, 1 Schneider CPC 6128, GT65 and lots of books
Still learning all the details on how things work.

zhulien

Thanks, I didn't see anywhere than mentions the ports but it seems the usefulness is very limited anyhow, as I mentioned I could get 64kb (4x 16kb) background task blocks and the rest only as a ramdisc or data storage.  Like a cpc 6128 (how i am using it) but with an additional ramdisc that cannot be much else.

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