Homebrew_PCBs

On Fri, 18 Mar 2016 15:17:41 -0700, you wrote:

>I suspect the part you were referring to is the 6845, the CRT chip used in
>the first IBM PCs.

Actually, no. The 6845 did 80 by 40 amongst other thins, the other
chip is either the 68047 (AMI) or the 6847(Y) from Motorola. It's
essentially the display section of a TV typewriter on a chip, although
IIRC it did need a color modulator since it put out R-Y and B-Y for
color information.

So I got the name wrong, but close.

Harvey

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>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>Sent: Friday, March 18, 2016 2:58 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] TV Typewriter: Custom G10 copper clad
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>On Fri, 18 Mar 2016 13:36:03 -0700, you wrote:
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><snip>
>>Anyway, I know I could get away with being inexact here. But the point of
>the exercise is to get as close to original as possible, which is why I went
>to the trouble of getting 1973 vintage chips. I'd also like to duplicate the
>process a hobbyist of that day would have used also, for my own education
>and experience. The experience is a big part of this. I want to be able to
>do what the museum can't/won't, let people see and use and get the feel for
>the thing. The museum will never show the most important part of the TVT,
>the boards, but I can with mine. And because I can I will, and I guess for
>that reason I want them to look right.
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>Then a suggestion I'd have would be to go do what you want, but be
>reasonable about the definition of "as reasonable". I think that the
>comment about the different variations having possibly different color
>boards is realistic, although I don't remember any SWTP product that I
>saw having paper boards (although there were a lot out there).
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>NEXT: I'd design the same thing using modern technology, and build
>one of them. That would give people a unique idea of just how far
>technology has come in about 50 years. (note: feel free to embellish,
>but have the basic mode be exactly what the original did).
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>I seem to remember a 68045 chip that was designed to be a similar
>style of display.
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>Harvey
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>>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>>Sent: Friday, March 18, 2016 10:35 AM
>>To: Homebrew PCBs <Homebrew_PCBs@yahoogroups.com>
>>Subject: Re: [Homebrew_PCBs] TV Typewriter: Custom G10 copper clad
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>>Yeah
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>> And besides, there are scant few folks around in hobby electronics
>nowadays that have ever actually
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>>laid eyes on a finished (or unfinished) Lancaster TV Typewriter. It is
>totally obsolete by todays standards and state
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>>of the art.
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>>And, as Lancaster envisioned, the thing was to be enclosed in a kind of
>wooden desk-top enclosure, so
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>>nobody sees the circuit boards anyway.
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>>Too bad that a search can't somehow be made on the internet, inquiring if
>there is some
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>>"old-timer" (like me) that has a Lancaster TV Typewriter in a dusty pile of
>forgotten projects,
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>>and that way, you could get the "real" item and bring it back online.
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>>These are just suggestions.........now, don't everbody jump on me with
>snide remarks.
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>>Regards.
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>>Roland F. Harriston, P.D.
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>>***************************
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>> _____
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>>From: "Stefan Trethan stefan_trethan@... [Homebrew_PCBs]"
><Homebrew_PCBs@yahoogroups.com>
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>>Snip:
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>>Most people are going to look at you as if you are crazy for wanting a
>specific colour and weave of material. That is because you are crazy of
>course, and nothing to worry about.
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>>It will not help your quest at all, but consider buying double sided
>laminate (with copper on both sides). I found it much easier to obtain and
>just etch one side away completely for single sided boards. Of course it
>makes impossible to see the inside.
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>>Also mind that in any case the copper on the other side will severely
>change the colour you see, even if the seller provides a photo of the board
>side. The copper layer is actually a dark red underneath, completely
>different colour from the shiny top surface.
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>>ST
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