[Coco] Cheap alternative to the DE-1?

[CoCo Demus]

Wouldn't a R2R network more efficient ? As it keeps the R impedance ? On
RGB2VGA I use it.

On Wed, Oct 28, 2015 at 1:15 PM, Dave Philipsen <dave at davebiz.com> wrote:

> Actually, three resistors per channel would yield 512 colors (including
> black). Three bits yields 8 combinations or voltage levels or colors per
> channel.  There are 3 colors (RGB) or channels so 8 to the third power is
> 512.
>
> If you bump it up to four bits per channel you can have 4096 colors.
>
> Dave
>
>
>
> On 2015-10-28 13:40, Zippster wrote:
>
>> Probably a binary weighted DAC (resistor network) like many dev boards.
>> Three resistors per channel should give 64 colors (4 levels including
>> ground level per channel).
>> Add another bit per channel to go to 125.
>>
>> USB blaster clones are dirt cheap on eBay.  Like $4 or so.
>>
>> - Ed
>>
>>
>> On Oct 28, 2015, at 12:51 PM, Dave Philipsen <dave at davebiz.com> wrote:
>>>
>>> Well, the DE-1 doesn't have a DAC either, just a resistor network.  You
>>> could probably hack that board though to get more colors if you wanted.
>>>
>>> Another thing you'd have to consider on this board is that it doesn't
>>> have the built in USB Blaster like the DE1.  You'd have to buy a blaster on
>>> eBay or somewhere.  If you are patient you can sometimes find a DE1 on eBay
>>> that will go for around $90 or so.  I even saw one go for around $55 bucks
>>> once.  My experience finds that they are usually in excellent condition.
>>>
>>> Dave
>>>
>>>
>>> On 2015-10-28 12:32, tim franklinlabs.com wrote:
>>>
>>>> Yeah, you're probably right. I found another problem too. I found the
>>>>   schematic for it and they limit the video to 8 colors. Not DAC to the
>>>>   VGA connector. Just logic.
>>>>   Manual: [1]http://www.dukelanovic.com/A-C8V4%20MANUAL.pdf
>>>>   Schematic:
>>>>   [2]
>>>> http://d1.amobbs.com/bbs_upload782111/files_44/ourdev_671042EUF7C8.p
>>>>   df
>>>>   Shorter links too LOL!
>>>>     On October 28, 2015 at 12:23 PM Dave Philipsen <dave at davebiz.com>
>>>>     wrote:
>>>>     FWIW, I think Gary's project uses north of 9,000 LEs which means
>>>>     that
>>>>     even if you can trim it down to fit you won't have a lot of extra
>>>>     space
>>>>     for future expansion/additions. Not trying to be negative...I hope
>>>>     you
>>>>     get it working...would be an interesting project.
>>>>     Dave Philipsen
>>>>     On 2015-10-28 07:23, tim franklinlabs.com wrote:
>>>>     > I ran across this while surfing E-Pray this morning. It looks
>>>>     > interesting. For those, like me, who are interested in FPGA's,
>>>>     this
>>>>     > $70.00 unit seems to have everything needed to port Gary Beckers
>>>>     > CoCoFPGA to it:
>>>>     >
>>>>     >
>>>>     >
>>>>     [1]
>>>> http://www.ebay.com/itm/Altera-Cyclone-NIOS-II-SOPC-FPGA-Developm
>>>>     ent
>>>>     >
>>>>     >
>>>>     -Learning-Board-EP2C8Q208C8N-LCD1602/272020523309?_trksid=p2054897.c
>>>>     100
>>>>     >
>>>>     >
>>>>     204.m3164&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D2
>>>>     014
>>>>     >
>>>>     >
>>>>     0407115239%26meid%3D8d211755ec994eff8913982e805be0c8%26pid%3D100204%
>>>>     26r
>>>>     > k%3D12%26rkt%3D21%26sd%3D261661704545
>>>>     >
>>>>     > It uses a smaller FPGA so there may be a limit here. I'm not sure
>>>>     > how
>>>>     > many LE's Gary's code uses.
>>>>     >
>>>>     > This board: EP2C8 8,256 LE's
>>>>     > DE-1: EP2C20 18,752 LE's
>>>>     >
>>>>     > Also, there are only 2 PLL's and I'm not sure if both are
>>>>     connected
>>>>     > to
>>>>     > clocks. I bought a small FPGA that had 4 clock inputs with 2
>>>>     PLL's.
>>>>     > The
>>>>     > moron who designed the board connected the clock to one of the CLK
>>>>     > pins
>>>>     > not connected to the PLL's.
>>>>     >
>>>>     > This board: 2 PLL's This assumes there are clocks connected to
>>>>     > both.
>>>>     > DE-1: 4 PLL's DE-1 uses only 3 (one connected to the
>>>>     > external clock)
>>>>     >
>>>>     > Since Gary posted an "almost" up to date project of his 3.0 FPGA
>>>>     > code,
>>>>     > i went ahead and bought one to see if I can port it. It comes from
>>>>     > China, so it wont arrive for a while (slow boat from china joke in
>>>>     > real
>>>>     > life). I'll keep everyone posted.
>>>>     >
>>>>     > References
>>>>     >
>>>>     > 1.
>>>>     >
>>>>
>>>> http://www.ebay.com/itm/Altera-Cyclone-NIOS-II-SOPC-FPGA-Development
>>>>     -Learning-Board-EP2C8Q208C8N-LCD1602/272020523309?_trksid=p2054897.c
>>>>     100204.m3164&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%
>>>>     3D20140407115239%26meid%3D8d211755ec994eff8913982e805be0c8%26pid%3D1
>>>>     00204%26rk%3D12%26rkt%3D21%26sd%3D261661704545
>>>>     --
>>>>     Coco mailing list
>>>>     Coco at maltedmedia.com
>>>>     https://pairlist5.pair.net/mailman/listinfo/coco
>>>> References
>>>>   1. http://www.dukelanovic.com/A-C8V4%20MANUAL.pdf
>>>>   2.
>>>> http://d1.amobbs.com/bbs_upload782111/files_44/ourdev_671042EUF7C8.pdf
>>>>
>>>
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