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General Category => Amstrad CPC hardware => Topic started by: HigashiJun on 12:34, 19 January 20

Title: Question concerning dual ROM mod
Post by: HigashiJun on 12:34, 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.
Title: Re: Question concerning dual ROM mod
Post by: Bryce on 13:41, 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.
Title: Re: Question concerning dual ROM mod
Post by: HigashiJun on 14:06, 19 January 20
Thank you Bryce for your prompt and clear answer !

Cheers.
Title: Re: Question concerning dual ROM mod
Post by: GUNHED on 17:05, 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.  :)
Title: Re: Question concerning dual ROM mod
Post by: HigashiJun on 05:08, 20 January 20
Yeah, that's a good alternative but I like when everything is internal...

Title: Re: Question concerning dual ROM mod
Post by: GUNHED on 14:07, 20 January 20
Quote from: HigashiJun on 05:08, 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 :)
Title: Re: Question concerning dual ROM mod
Post by: HigashiJun on 04:59, 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.
Title: Re: Question concerning dual ROM mod
Post by: GUNHED on 12:59, 21 January 20
I understand that.  :) However, I couldn't live without expansion ROMs anylonger.  ;) :)
Title: Re: Question concerning dual ROM mod
Post by: HigashiJun on 13:24, 21 January 20
Hmm... Would be nice to have it internal too.
Title: Re: Question concerning dual ROM mod
Post by: GUNHED on 18:49, 21 January 20
Quote from: HigashiJun on 13:24, 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 (http://8bit.yarek.pl/hardware/cpc.rom/index.html)
Title: Re: Question concerning dual ROM mod
Post by: HigashiJun on 08:58, 22 January 20
Thanks ! Missed this one...
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