19 May
2015
19 May
'15
4:03 p.m.
I've been brainstorming about hypothetical hardware for converting video from vintage
8-bit computers to drive modern monitors well, with support for all of the dirty tricks
like color aliasing that many of them used. One of the things I would like to understand
is the range of RF frequencies used by the machines that connected to ordinary
televisions.
My old Color Computer used US VHF channels 3 or 4 for NTSC video. I found a reference to
the ZX Spectrum using UK UHF channel 35 for PAL video.
What other channels were used all over the world by 8-bit home computers (and video games,
too, I suppose), and which TV standards were used with them?
19 May
19 May
4:40 p.m.
On May 19, 2015, at 1:03 PM, Mark J. Blair <nf6x at nf6x.net> wrote:
My old Color Computer used US VHF channels 3 or 4 for
NTSC video. I found a reference to the ZX Spectrum using UK UHF channel 35 for PAL video.
My NTSC ZX81 uses US UHF 34/35.
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5:57 p.m.
On May 19, 2015, at 1:46 PM, Mark J. Blair <nf6x at nf6x.net> wrote:
Did anything use US VHF channel 2? I can't recall whether I have seen that used
before, but I have a feeling that I might have.
The NTSC Atari 2600 switches between 2 & 3.
--
Follow me on twitter: @FozzTexx
Check out my blog: http://insentricity.com
6:24 p.m.
On Tue, May 19, 2015 at 5:22 PM, Fred Cisin <cisin at xenosoft.com> wrote:
The NTSC Atari 2600 switches between 2 & 3.
On Tue, 19 May 2015, Kyle Owen wrote:
My bad, yes. And I see this has already been discussed...
As do the TRS-80 CoCos, if I'm not mistaken.
3/4 for the ones intended for USA. Other options might have been
available for export models.
7:14 p.m.
On May 19, 2015, at 14:57, Chris Osborn <fozztexx
at fozztexx.com> wrote:
Thanks! I'm pretty sure that a 2600 is where I saw channel 2 used, then.
On May 19, 2015, at 1:46 PM, Mark J. Blair
<nf6x at nf6x.net> wrote:
Did anything use US VHF channel 2? I can't recall whether I have seen that used
before, but I have a feeling that I might have.
The NTSC Atari 2600 switches between 2 & 3. 
6:19 p.m.
On Tue, 19 May 2015, Mark J. Blair wrote:
Did anything use US VHF channel 2? I can't recall
whether I have seen
that used before, but I have a feeling that I might have.
Certainly POSSIBLE. But channel 2 tends to be occupied in MOST places.
3 was used by VCRs, etc, and 3&4 switchable just in case a community had
an active station on 3.
4:47 p.m.
My old Color
Computer used US VHF channels 3 or 4 for NTSC video. I found a reference to the ZX
Spectrum
using UK UHF channel 35 for PAL video.
My NTSC ZX81 uses US UHF 34/35.
5:46 p.m.
On May 19, 2015, at 13:47, tony duell <ard at
p850ug1.demon.co.uk> wrote:
Most, if not, all home computers sold to connect to TVs in the UK were set to use our UHF
channel 36.
VHF channels were not used for broadcast 625 line TV
in the UK, and most TVs could not tune to them. So you
will not find a UK home computer using VHF RF output.
Thanks! Those are the sorts of details that are hard to know with only my US computer/TV
experience.
That NTSC ZX-81 is the first I have heard of a computer with UHF TV output in the U.S.,
but it makes sense to minimize the hardware changes for the U.S. market. Might have used
the same modulator, possibly with a coil adjusted a bit differently in the factory.
Native US gear was all VHF in my experience. Usually switchable between channels 3 and 4
to avoid whichever channel had a strong local station, and also commonly using an Astec
modulator. I still have a nagging feeling that I might have seen something with channel 2
output, but can't remember where I think I saw it.
6:33 p.m.
On Tue, 19 May 2015, tony duell wrote:
Most, if not, all home computers sold to connect to
TVs in the UK were
set to use our UHF channel 36.
In San Francisco bay area, including Silicon Valley, there was a very
strong independent station on 36.
On 32? there was an insane? speed-freak? preacher ranting biblical
conspiracy theories, etc. 24/7
But those two strong signals made it easier to find the 34 of the
Sup'R'ModII
6:51 p.m.
But those two strong signals made it easier to find
the 34 of the Sup'R'ModII
Note that in those days, TVs had KNOBS!
VHF had individual click detents, with a "fine tuning" analog knob that
would take you almost to what you wanted to tune.
UHF didn't even have detents, with a continuous analog knob (one coarse,
one fine) from 14 to 83.
Very soon after that, TVs started to have digital channel selection,
and "Don't touch that knob!" became an anachronism.
6:18 p.m.
On Tue, 19 May 2015, Mark J. Blair wrote:
My old Color Computer used US VHF channels 3 or 4 for
NTSC video. I
found a reference to the ZX Spectrum using UK UHF channel 35 for PAL
video.
What other channels were used all over the world by 8-bit home computers
(and video games, too, I suppose), and which TV standards were used with
them?
About 90% of the stuff sold in USA used VHF 3, or VHF 3&4 switchable.
The Sup'R'Mod II used UHF 34. It was significant in its popularity with
early Apple ][, and apparently (based solely on the keyed 4-pin
Berg connector) was what was considered in the design of CGA.
21 May
21 May
3:11 p.m.
At 03:03 PM 5/19/2015, Mark J. Blair wrote:
I've been brainstorming about hypothetical hardware
for converting video from vintage 8-bit computers to drive modern monitors well, with
support for all of the dirty tricks like color aliasing that many of them used.
Hasn't this list discussed existing devices that work for this task?
They're aimed at the game console market.
- John
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ard＠p850ug1.demon.co.uk -
cclist＠sydex.com -
cisin＠xenosoft.com -
fozztexx＠fozztexx.com -
jfoust＠threedee.com -
kylevowen＠gmail.com -
nf6x＠nf6x.net