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Re: An

Hi Leon!  Would you please resend your last email on VDP V2 build and
test?  I can't find your message on generating video from the RAMDAC
and I am afraid I have lost some vital information.

We can wait as long you need before going to press with S-100 VDP V3.
The prospect of a working (or not) RAMDAC is just too good!

Thanks and have a nice day!

Andrew Lynch

On Jan 13, 6:04 pm, Elsid <le...@swiftdsl.com.au> wrote:
> Hi Andrew,
> I'm sorry I haven't given the S-100 VDP board much attention lately.
> In my last effort working with John I saw video coming out of the RAMDAC.
> It was garbled so I need to sort out what is going on there. If you can
> delay the next prototype for a few weeks I'll do a bit of debugging to see
> if I can get correct video out of the RAMDAC.
> See below for email re last effort:
> I’ve managed to get video out of the RAMDAC. For real this time.
> I was looking at the colour bus data going into the RAMDAC along with the
> CLOCK and BLANK signals.
> The BLANK signal seemed to be running at about half the CLOCK frequency.
> This would mean all of the color bus data was not being accepted as valid.
> The BLANK signal is p7 BLEO on the VPU. I bent the pin out and soldered a
> 1k pull up to the BLANK signal going to the RAMDAC so it was -continuously
>  inactive.-Now I have Video out p25,26,27 of the RAMDAC but it’s not
> exactly correct.-I suspect the colour bus data is not correct. I think in
> the video mode we are using, there is only 4 bits of valid data that are
> repeated on -the top 4 bits. Also the colour palette order in the VDP is
> G,R,B whereas it’s R,G,B in the RAMDAC. We may be able to correct these
> problems -using the Pixel mask register and a reordered RAMDAC colour
> palette, what do you think?
> Leon Byles
> On Monday, January 14, 2013 7:08:03 AM UTC+10, lynchaj wrote:
> > Hi!  The S-100 VDP V3 prototype is almost ready to go.  Are there any
> > builders who would like to build and test this new version?
> > Were there any more changes from the last round of build and test (S-100
> > VDP V2)?
> > This board is a V9938 video display processor and AY-3-8910 sound
> > generator.  It is roughly an MSX2 class color graphics and sound board.
> > I’d like to get some prototype boards if anyone would like to chip a bit
> > for some.
> > Thanks and have a nice day!
> > Andrew Lynch- Hide quoted text -
> - Show quoted text -