ADDRESSING RAM AT 16K+

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gammaray
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Re: ADDRESSING RAM AT 16K+

Post by gammaray »

No wonder my chip-select / write enable didnt work!
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XavSnap
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Re: ADDRESSING RAM AT 16K+

Post by XavSnap »

siggi wrote: ↑Thu Oct 19, 2017 9:59 am There is still an error in this schematic: At edge connector side A pin 1 should be D7' (not D7)
Siggi
:oops:
All mys confused !
Thanks Siggi, it now a ~D7'~.
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fordp2002
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Re: ADDRESSING RAM AT 16K+

Post by fordp2002 »

1024MAK wrote: ↑Wed Oct 18, 2017 7:04 pm If you look at this schematic (where some errors have been corrected, ignore the French video circuitry) which shows the edge-connector connection points (the X's in square boxes), it may help.
Image

Both /ROMCS and /RAMCS have series resistors between the ULA and the relevant chips. The edge connector pins are on the memory side of the resistors. Hence why the ULA outputs can be safely overridden.

Mark
Is it me or does that Z80 not have two PIN 19s. I think Halt is PIN 18!
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1024MAK
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Re: ADDRESSING RAM AT 16K+

Post by 1024MAK »

Yes, /HALT is on pin 18. Thanks for spotting that error!

Mark
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XavSnap
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Re: ADDRESSING RAM AT 16K+

Post by XavSnap »

Hi,

Thanks!
Picture updated to clear the Z80 pinout.
z80.JPG
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