sinclair spectrum eprom swap gone wrong

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1024MAK
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Re: sinclair spectrum eprom swap gone wrong

Post by 1024MAK »

External expansions/interfaces do their own address or I/O decoding, they don't use the control signal(s) from the ULA.

Further, to prevent the internal ROM from being accessed, they apply a logic high to the /ROMCS line. This overrides the ULA control signal to the internal ROM.

Mark
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jojo
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Re: sinclair spectrum eprom swap gone wrong

Post by jojo »

Mark , thanks !!

so more inversigation work to do .
Zx81-16k exp.- Spectrum 48 - Spectrum 128- Interface 1 - DIVide - Zx flashcard- Zx printer - Ram turbo-Velleman interface system-Currah microspeech -Ql - 512k exp.- Ql printer - Cst floppy interf.- Double 3.5 floppy- Minerva - Qimi-and much more .
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