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Offline HigashiJun

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Question concerning dual ROM mod
« on: 13:34, 19 January 20 »
Just a question for all specialists here:

Is the 10K pull resistor really needed in the dual ROM mod for CPC ?

Couldn't it be done safely without it ?

If really needed, can someone explain the reason why this resistor has to be added (ESD, ...) ?

Thanks in advance for your answers.
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Offline Bryce

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Re: Question concerning dual ROM mod
« Reply #1 on: 14:41, 19 January 20 »
Hi, yes the 10K resistor is really needed. If it wasn't there, the input that needs to be held high wouldn't be high, it would be floating. Other than making the system completely unstable, it can also cause the EPROM to consume more current.

Bryce.
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Offline HigashiJun

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Re: Question concerning dual ROM mod
« Reply #2 on: 15:06, 19 January 20 »
Thank you Bryce for your prompt and clear answer !

Cheers.
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HigashiJun

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Re: Question concerning dual ROM mod
« Reply #3 on: 18:05, 19 January 20 »
Or... just get one of these RAM and ROM expansion cards. They're cheap an well done. Look for MegaFlash, X-MEM, M4, SF3, 4 MB RAM expansion and so on... For the CPC464 it's the best to get Revadhinos RAM expansion and maybe the M4 as ROM expansion. For 6128 the X-MEM is awesome.  :)
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Offline HigashiJun

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Re: Question concerning dual ROM mod
« Reply #4 on: 06:08, 20 January 20 »
Yeah, that's a good alternative but I like when everything is internal...

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HigashiJun

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Re: Question concerning dual ROM mod
« Reply #5 on: 15:07, 20 January 20 »
Quote from: HigashiJun on 06:08, 20 January 20
Yeah, that's a good alternative but I like when everything is internal...

Sure, one of my CPC6128 hat 4 MB RAM with 2,5 MB Flash-ROM and an IDE device (8255IDE) all internal. Lot's of fun at mixed meetings.  ;D :)
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Offline HigashiJun

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Re: Question concerning dual ROM mod
« Reply #6 on: 05:59, 21 January 20 »
That's what I also plan to do: internal 4MB from Yarek, dual AMSDOS/PARADOS ROM, internal IDE (from JonB) and maybe much more depending on many factors...

I love to keep my retros' external look as genuine as possible.
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HigashiJun

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Re: Question concerning dual ROM mod
« Reply #7 on: 13:59, 21 January 20 »
I understand that.  :) However, I couldn't live without expansion ROMs anylonger.  ;) :)
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Offline HigashiJun

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Re: Question concerning dual ROM mod
« Reply #8 on: 14:24, 21 January 20 »
Hmm... Would be nice to have it internal too.
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Re: Question concerning dual ROM mod
« Reply #9 on: 19:49, 21 January 20 »
Quote from: HigashiJun on 14:24, 21 January 20
Hmm... Would be nice to have it internal too.
Yes, Yarek did that for me. You can contact him here:
http://8bit.yarek.pl/hardware/cpc.rom/index.html
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Offline HigashiJun

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Re: Question concerning dual ROM mod
« Reply #10 on: 09:58, 22 January 20 »
Thanks ! Missed this one...
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