[Coco] hardware

[John Eric]

just good design practice - keeps the unused gates from randomly switching states and drawing excess current. probably not an issue with your sync generator. The video cable Marty Goodman used to make used the 74ls02 to generate the sync and was connected to the joystick port to get the 5v, in which case the unused gates would most assuredly diminish the joystick resolution if they were to draw too much current. jeric
p.s. also good design practice to include a bypass or decoupling capacitor (.1uf) across vcc and gnd of the chip :)




________________________________
From: mike delyea <mdelyea at gmail.com>
To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
Sent: Saturday, January 3, 2009 10:00:31 PM
Subject: Re: [Coco] hardware

Why is that a good idea?  My circuit still works despite my lack of
knowledge. Is this a "best practice" type of thing or a "look out, its
going to blow" type of thing?  Should I be worried?  I know nothing
about electronics, never took it in school and I don't know any
theory.  Whatever - I - who knows nothing - was still able to build a
simple circuit.  And basically, I enjoyed myself putting it together.
I'd like more of those simple projects.  If anybody is interested I
could post pics on my web site.

On Sat, Jan 3, 2009 at 10:37 PM, John Eric <jet.pack at ymail.com> wrote:
> it's also a good idea to disable the unused gates in the 74ls02 by connecting the unused inputs (not the outputs) to either vcc or gnd. with a 74ls02, i use vcc.
>
>
>
>
> ________________________________
> From: mike delyea <mdelyea at gmail.com>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Sent: Saturday, January 3, 2009 9:08:28 PM
> Subject: Re: [Coco] hardware
>
> The particular Atari monitor I was using was a 1080.  There is no
> specific info on the internet for the 1080.  All references I found
> were for the 1084, which is supposed to be the same as the 1080,
> unless you got the other model with the 26 pin connector.  My travails
> trying to get that monitor working, and my ultimate success can be
> found here.
>
> http://www.coco3.com/modules.php?name=Forums&file=viewtopic&p=1718&highlight=#1718
>
> On Sat, Jan 3, 2009 at 9:54 PM, John Eric <jet.pack at ymail.com> wrote:
>> His atari model may have needed differing sync levels? or composite sync? or something? Jeric
>>
>>
>>
>>
>> ________________________________
>> From: BookWorm <bookworm at cavenet.com>
>> To: coco at maltedmedia.com
>> Sent: Saturday, January 3, 2009 8:37:48 PM
>> Subject: Re: [Coco] hardware
>>
>>> I have pretty minimal hardware skills,
>>
>> You should see mine...
>>
>>> but I did manage to piece
>>> together a circuit to invert the coco video signal so I could drive an
>>> Atari monitor
>>
>> Are you refering to an EGA monitor?
>>
>>>(surprisingly no one else on the list could help me - so
>>> I ended up doing it all myself- figuring out the correct chip and
>>> designing the circuit).
>>
>> That's because Atari monitors are already compatible with the CoCo 3. They
>> don't require converting.
>>
>>> soldering (heh, i almost wrote slobbering)
>>
>> That's what I do with a slodering iron too.
>>
>>> Forget about the coco4
>>
>> I'm trying.
>>
>>> and FPGA
>>
>> Actualy, I like James's FPGA GIME upgrade. I hope I can order one soon.
>>
>>>and hard drives
>>
>> You don't have a hard drive? Cloud 9 sells SCSI and IDE controllers.
>>
>>
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>>
>>
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