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| From: Bionic (all posts)
Date: 1998-11-19
Subject: Re: TED Timings
|
-----Ursprüngliche Nachricht-----
Von: Christian <solder@gmx.net>
An: plus4@c64.rulez.org <plus4@c64.rulez.org>
Datum: Mittwoch, 18. November 1998 20:37
Betreff: Re: TED Timings
On Mon, 16 Nov 1998 20:34:47 -0000, Tim Böscke wrote:
>>I wonder whether anyone has exact timing diagrams of the TED signals ?
>>I am especially interested in the MUX , RAS and CAS timing.
>Hi Tim,
>I have 3 sheets with diagrams from a multichannel logic-analyzer. Maybe that this can
>help you. Otherwise in the Commodore-Plus/4-Service-Manual are a lot of informations
>about the timing. The plus/4 uses a fixed raster for access to RAM and for Refresh with
This would probably help me - do you have the opportunity to scan them ?
I neither have the Service Manual. Is it downloadable somewhere ?
>Crystal/10 (PAL). This is the RAS- and MUX-clock while RAS activates some ns before
>MUX switched the adress-multiplexer to the columns. The TED uses RAS-only-refresh,
>this needs a generated row-adress by TED. Because it's only 8 Bit you can refresh
>max. 256kbit-chips with this.
Yes , I know. However 1Mx1 and 256kx4 Chips offer a Hidden Refresh mode without address transfer,
which allows refreshing while the output data is still valid. Since the Plus/4 uses rather slow memory timing it should be easily possible to perform one or more refresh cycles while CAS is low..
The only thing required to do is to pull RAS high at least 25ns after CAS went low and pull it low again after 60ns..
With a bit of luck this is just a minor modification to the 256k ram extension, but it would enable us to use 1Mx1 chips and even simms.. :)
>Christian
>You will find infos for Commodore plus/4-homecomputers, OS/2-Warp, swap MP3's
>on my homepage
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