On Mon, 12 Dec 2011, John Foust wrote: Like the Coco 1, it should be TRIVIAL to tap a composite video signal (almost-NTSC) output into a DVD RECORDER, write DVDs, carry them over to a PC, and play them there :-) There ARE cheap TVs available, that DO have analog tuners.

would this also work with a c64? Dan

On Mon, 12 Dec 2011, Dan Gahlinger wrote: C64s already have separate chroma and luminance output. I built an adapter and plug mine directly into an S-Video monitor input. --

Yes. Many (even most) of them have composite inputs, and some even have S-video inputs. I used an Aurora Fuse card for this in my MDD until I got a FireWire Canopus ADVC-300. -- ------------------------------------ personal: http://www.cameronkaiser.com/ -- Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com -- Everything is permissible, but not everything is expedient. -- 1 Cor 6:12 --

Now that you and Cameron mentioned it, I'll look through my junk pile. I am pretty sure I have at least one TV card in there. Thank you. -----Original Message----- From: David Riley <fraveydank at gmail.com> Sender: cctalk-bounces at classiccmp.org Date: Mon, 12 Dec 2011 13:38:58 To: General Discussion: On-Topic and Off-Topic Posts<cctalk at classiccmp.org> Reply-To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Subject: Re: TV -> D-Sub converter possible? On Dec 12, 2011, at 12:15 PM, vintagecoder at aol.com wrote: Often enough, yes. You just need to look for the appropriate ports; some of the REALLY cheap ones only have a tuner and nothing else. I really liked the AVI TV Wonder that I have (CX2388x-based, red PCB); it had a little purple breakout box with the composite, S-Video and audio connections so that everything else could fit on the card bracket. For Linux, my best luck has been with bt848/878 (almost the same chip) followed by CX2388x (the next step up after Conexant bought Brooktree; there are newer chips in the series that support e.g. PCI Express, but I don't know their level of support under Linux). There are a handful of Philips chips supported, but I've never tried them. The Windows viewing apps that come with the cards are almost universally terrible, but a good third-party one I've used is DScaler (it's been a while since I've fooled around with it, though, and they were going through a major project renovation, so it could be either better or worse by now). For Linux, I always preferred fbtv, but most people don't like fooling around with the framebuffer layer any more than they have to. I really liked the ability the framebuffer layer gave me to create custom graphics modes with weird sizes and fixed frequencies that optimized the experience; alas, none of that is likely to work well without an analog monitor anymore. I also liked being able to just start the viewer without having to start X. I don't know what the general favorite is for operating it under X; when I was using it, it was xawtv. I imagine that MythTV probably has a Video4Linux backend? - Dave

On 12/12/2011 12:15 PM, vintagecoder at aol.com wrote: Indeed, those are the SAME signals! Think about it. :) -Dave -- Dave McGuire New Kensington, PA

On Dec 12, 2011, at 4:50 PM, Dave McGuire wrote: Oh, I realized he meant the modulated outputs from a computer/console. Yeah, same signal, less propagation loss over coax. And it's really just the composite video signal modulated by a carrier; normally, if something only provides the RF out (like the CoCo, as folks have mentioned), you can tap the composite signal somewhere further up the chain if you need the baseband signal. - Dave

Well, I didn't write that, but, as I read it, "less" there is the sense which could just as well be written "minus". /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML mouse at rodents-montreal.org / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B

On 12/13/2011 09:34 AM, David Riley wrote: Oh you're absolutely right; I thought you were saying RF had less propagation loss over coax than video over coax. My apologies for my misinterpretation of what you said. I figured as much; just mentioning it for the sake of our frequently-searched archives. I'm well aware that you Know Your Stuff(tm). :) -Dave -- Dave McGuire New Kensington, PA

On 12/13/2011 04:56 PM, Tony Duell wrote: Of course, for the strictest case of just the modulator. But those filters on the outputs select what we were really after. ;) -Dave -- Dave McGuire New Kensington, PA

I am going to try to expalin the various types of video signal... Let's start with monochrome. We all know that in a CRT monitor the electron beam scans the screen one line at a time. The main part of the analogue monochrome signal controls the intenstiy of this be am, and thus the brightness of that point on the screen. We also need to synchronise the scanning of the electron beam in the monitor with the source of the signal, to do this it's conventiaonal to hae a pair of signals, one to mean 'start a new line' (horizontal, or 'line' sync) the other to mean 'start a new screen (vertical or 'frame' sync). If the monitor is near the video source, you van send these 3 signals over 3 seaprate wires. Or you can combine the 2 sync signals into one to make something called 'composite sync' and send that over one wire and the video infortmation over another wire. Or you can put it all into one signal, this is known as 'composite video', Of course a major use of such signals is television. You cna't send a cposite video signal directly by radio, jsut as you can't send the audio output of a microphone driectly. In both cases you have to use that signal to modulate an radio frequency carrier. The receiving set demodulates the signal, gettting back the original composite video or audio signal and then outputs that. Now in the 'home computer' era, monitors were expensive, and most TV sets did not have composite video input sockets, they just had sockets to conenct an aerial. Therefore, many home omputers inculded a device called an 'RF modulator' which is bnasically a very low power TV transmitter, It produces an RF signal and modualtes it wit hthe composite video signal fro mthe computer's video circuitry. The result can be fed to thraerial input of a TV set, as it's similalr electrically to the signal you'd get froma TV aerial. The TV set then demodulates it back to composite video and displays it. Now for colour. It is a quirk of the uman eye that you can get the visual effect of any paritcular colour by seeing the appropriate amounts of red, green, and blue light. So you could have 3 separate signals, one for each or red, green, and blue along with the synchronisation signals. This is the RGB video system (for example VGA and its derivatives). Or you coudl combine the syncs with one of the colour signals to make a composite signal, and have hte pther 2 colours separate (for soem reason, the green signal is nearly alwyas used to make the composite signal -- this is the 'sync on green#' system ).One vey obscure method is to combine one of the syncs iwth one colour and the other sync with a different colour, again ending up withe 3 signals. I think Tektronix ddi this at one point, you are not likely to come across it. However, having RGB separate is not suitable for television. One of the requiremetns for a colour television system is that is has to be compatible -- both ways -- with monochrome TV. What I mean by that is that a colour TV must display a monochrome TV signal (with no colour information in it) as a black and white picture. And a monochrom TV set -- even one designed before the colour system was introduced -- must display a colour TV signal as a good monochrome picture. FOr tht reason, the 3 colour signals have to be processed to form other signals. One of this is the luminance (or 'Y') signal, which is a weifgthed sum of the R,G, and B signals. This, if turned into composite video by adding the syncs will display correctly as a monochrome signal. The colour information can be encoded in various ways. The NTSC system has a 'colour suubcarrier' sgianl which is modulated to carry this information/. At the start of each line, a short burst of the subcarrier is sent to give the scoder circuit a phase reference. Then throughout the line, the phhase of this subcarrier determiens the hue (colour) of that part of the picture, the amplitude of the subcarrier determines hte saturation (who far the colour is from what -- for example red and pink could be the same hue, but red has a higher saturation than pink). PAL is much the same except that the phase of the burst and the subcarriar is fillped on every other line, so that phase errors in the system just cause slight desaturation of the colours rather than a change in hue (which is much more noticeable). Once you have combined the colour and luminance information, you have a composite colour video signal. This can then be modualted onto an RF carrier and transmitted. Or in the case of a home computer it can be fed to the RF modualtor circuit and set to the aerial input of a colour TV set. Of course sure ot the compatibility requirements I've mentioend, a home computer that doesn't output colour information (say a ZX81) will work with a monochorme or colour TV set (and display a black and white picture), a home computer that outputs colour information (say the CoCo) will work with a monochrome TV, you just don't get to ser the colours. S video is a conenctor carrying 2 signals. One is the lumninance information (only), the other is the colour information encoded using NTSC or PAL or whatever. The recent-ish system of 'component video' is 3 signals. I beleive (please correct me), that despite the colours of the plugsand sockets uses, these are not separate RGB signals. They are the luminance signal and 2 'colour difference' signals (I suspect R-Y and B-Y). SO far I've said nothign aobtu the scan rates. Home computes, designed to work with TV sets, wll use the same scan atss as the applicable TV ssytem. The horixzontal scan is around 15kHz, the vertical scan is very close ot the mains frequency. Other machiens, particularly workstations can have just about any scan rate immaginable. Interconmverting between composite video, RF-modulated video, adding/decoding the colour, etc are relatively simple compared to converting the scan rate (which often invovles storing the image in a memory deivce nad reading it out at a different rate). For that reason, if toy have to convert a monitor to use with a strange machine, pick one with the same scan rates and encode/decode the video signal appropriately. In geneeral, it is easier to modifiy a monitor to handle a differnt vertical scan rate htan a differnet horizontal scan rate. The European and US TV hjorizotnal san rates are close enough that most monitors that will work with one will wrok with the other, and often a tweak of the vertical hold control will get the vertical to lock as well. If not, it's a fairly simple modification if you have the schematic. A few practical hints... Most home computes have an RF modualtoe module inside. This is a metal box on the PCB, the cable to the TV aerial socket plugs into it. There are 3, 4 or 5 conenctions to this unit, including the metal case (which is systme ground). The other connections are a poer input (often 5V or 12V), compostie video in, audio in (if the =comptue sends sound otthe TV) and maybe a tuning or channel select input. The compostie signal will often tive a composite monitor directly, sometimes you need a simple transistor buffer circuit. I would recoment bypassign the modualtor (and thus the demodualtor circuit in the TV set) if your display device has composite inputs, you get better quality and there's less to go wrong. If you want to strt makniong your own PAL or NTSC to RGB decoders, I would look at hte Philips chips from the 1990s. Philips published data sheets on them (which is a good start...) and you can use the scheamtics of their TVs as an 'application circuit'. Be warned that settign up a colour decoder is not that easy. -tony

Someone wrote: Mouse wrote: There are *many* alleles for the green pigment, and at least a few for red. The genes are long and it is common for them to get transcribed wrong, i.e., to have a gene for the green pigment that partway through turns into a copy of the tail of the gene for the red pigment. This usually results in a pigment with a frequency response peak close to the linear interpolation of the fraction of the green and red gene components. That still means that any color perceptible by that person could be produced as the sum of three primaries, though the necessary primaries may be different than those necessary for another person. No one has been able to demonstrate that this has any effect; it is possible that the brain is unable to distinguish red1 from red2, which would then effectively be just a slightly wider peak for red. It's certainly possible to create B=100 with G=0. It's not surprising that CRTs and LCDs do not have sharp enough spectral lines to do this. There are laser-based display systems that do. With the right three primaries for an individual (possibly four for a tetrachromat), with sufficiently sharp spectral lines, it is quite possible to produce the equivalent to any other perceptual color.

On Mon, 12 Dec 2011 vintagecoder at aol.com wrote: MANY have composite video imupts. Watch for that, even though that isn't needed for THIS - you'll want it for Apple][, TRS80 model 1, C64, Amiga, CGA, etc. For those that don't, cable the RF output of the Coco to the analog TV antenna input of the TV card. Tell the Coco that it is connected to a TV (as if it cares); tell the TV card and connected computer that it is receiving an over-the-air broadcast on channel 3. If you can't do cables, connect an antenna [and maybe a linear amp] to the RF output of the Coco, Tune the TV card to cvhannel 3, and keep an eye over your shoulder for FCC broadcast enforcement.

On Dec 12, 2011, at 12:12 PM, Vintage Coder wrote: HDMI should be passively convertible to DVI (someone correct me if that's not true when it carries audio information; thus far, it's worked fine for me). S-Video is the next step up from composite, with the luma (brightness) and chroma (color) information separated out. It may not be popular in the UK (though I seem to recall the SCART connector has some pins for it). It will give you a much better picture than composite video if you have the option. Typically it's a round mini-DIN connector with 4 pins and a plastic alignment bit. - Dave

This reminds me of a funny story (well, it wasn't funny at the time). S-video connectors are, possibly not coincidentally, the same plug that Apple Desktop Bus uses, and I use S-video cables as extension cables since they are cheap and readily available. However, what you can't use is an S-video switchbox as a cheapo K-M switch. So here's today's trivia question: when I did this, the system kept acting like I was pressing the power button. :) The same principle allows you to create an "ADB boot dongle" for non-MacOS systems. My 7300 NetBSD system had one plugged into the keyboard, since NetBSD would ignore that, and even if the PMU was not working correctly it would always boot it after a power failure. -- ------------------------------------ personal: http://www.cameronkaiser.com/ -- Cameron Kaiser * Floodgap Systems * www.floodgap.com * ckaiser at floodgap.com -- Spotted on a coffee mug: "Say NO to drugs" -- Chuck Reiman, r.h.f ----------

On Dec 13, 2011, at 3:47 PM, Tony Duell wrote: Yeah, ADB had 4 pins in a Mini-DIN (exact same connector as standard S-Video): +5v, ground, serial and power-switch. The keyboard's power key is hard-wired to pull down the power switch pin. S-Video has two video signals and a signal ground, so I guess the switch-box grounded those instead of tying them to the input (or opening the circuit when deselected). - Dave

On 12 Dec 2011 at 17:12, Vintage Coder wrote: Probably close to 20 years ago, I expressed an interest in being able to view PAL VHS tapes here in NTSC-land. A friend from the UK sent me a PAL VHS player and I tracked down a fellow who made PAL-to-RGB decoder kits. I found that my Mitsubishi Diamond Scan monitor would display the RGB just fine. I still have the plans for the kit and can forward them on, if it would help. --Chuck

On Mon, 12 Dec 2011, David Riley wrote: To get peak performance, use unshielded wires and twist them together loosely instead of connectors. If it isn't a signal-hostile environment, the machine won't feel at-home.

Tony said: I've been away from my tools too long (don't ask) and I wasn't thinking of doing any surgery on the COCO since it's pristine. The whole deal is I don't have a TV, don't have a need for it or really any room for one, but I do have plenty of monitors. If I can't get a TV card to work or anything else becomes an issue I'll ask again, when I actually have everything in front of me so I can ask quasi intelligently instead of based on what I remember from the 1980s sometime which was when I bought it and put it back in the box after not using it much. Yeah but I don't have a TV! I think somebody said the COCO doesn't have composite output. Hmmm, will any old CRT monitor work? I might be pursuaded to see if I can scrounge one of those even though finding a home for it would be a problem. Was hoping to avoid the CRT death rays though since I did enough of that for decades. The newer flat screens seem much healthier. Thank you and everyone. I guess we can let this thread die for now.

F connectors are only really used for satellite1st IF connections over here (output of the LNB, etc). The TV aerial plug is a push-in thing commonly called a 'coax plug' over here. UK(onlt) TVs often do not cover the VHF channels (continental European ones often do). But then what sort of CoCo 2 is it? There is a UK vertsion of the CoCo 2 which outpuys PAL encoded video and has a UHF mnodulator outputting on our TV channel 36. UK TVs with analogue tuner/decoder circuits can tuen to that. -tony

At 04:18 AM 12/14/2011, Christian Corti wrote: Yes, I understood the panoply of standards, and certainly the TV companies do, too. It's perfectly possible they ship a TV that can handle the standards of a few countries. After all, the frequencies aren't that different, and the decoding is largely done in software these days. Inside your average CD TV today are two boards, one the power supply, another whose chips look pretty much like a PC motherboard. - John

On 14/12/11 5:00 PM, Tony Duell wrote: That is because they want you to buy a whole new monitor when the crappy Chinese electrolytics swell up and die. I've "field repaired" at least five units in this way, giving them a happy rebirth - The rest of the monitor lasts a lot longer than the stupid capacitors do. Building in obsolescence like this should be a crime that puts people behind bars. --Toby

On 14 Dec 2011 at 21:32, Dave McGuire wrote: I absolutely *love* the idiots who design CCFL inverter supplies for those monitors with 85C-rated electrolytics hot-glued to heatsinks. It's almost as if they're designing the thing to fail. --Chuck

On Dec 14, 2011, at 9:32 PM, Dave McGuire wrote: Almost laughed out loud at that one. Seems like it would cost more to make the fake if it weren't done by the millions. - Dave

On 12/15/2011 08:21 AM, Holm Tiffe wrote: While I can't speak to the provenance of this particular one, Chinese component clones are a very real, very large problem in the electronics industry, making it into the industry news media each and every week. Given the state of the industry at this point, there's no reason at all to suspect it to be a hoax. -Dave -- Dave McGuire New Kensington, PA

On 12/16/2011 11:50 AM, Holm Tiffe wrote: I don't agree. It certainly *may* be, but there's no compelling reason to say so "for sure". I work in the electronics industry; counterfeit components are a very real, very big, very current problem here. That's not me guessing, wondering, or saying it may be so; this is a well known thing throughout the industry...a simple verifiable fact. There was another big article about it in a weekly trade rag just yesterday, and there's lots of new legislation happening to try to curb it. As far as the capacitor-within-a-capacitor in the picture, don't underestimate the cheapness of Chinese labor. I'm sure they have children cranking those out by the hundred every day. With bigger capacitors costing several dollars apiece, especially high-temp and low-ESR capacitors, the demand for which is skyrocketing now, it's probably even more profitable than relabeling cheap chips as expensive ones and flooding them onto the market. They're certainly quite smart; a lot smarter than the rest of us it seems. So, since they're making and exporting counterfeit components by the container load, they must see quite a profit from it. -Dave -- Dave McGuire New Kensington, PA

It should be noted that counterfeit electronic components are absolutely nothing new. Back in both the 1920s and the 1950s, there were huge rashes of bogus tubes, and even in the 1970s, there were scads of crap semiconductors. -- Will

On 04/01/12 3:57 PM, Ethan Dicks wrote: Precisely. And that's why we have this problem, at all levels. --T

Although they do expect me to repair the signal-prpocessing PCB... In any case I regard the information in service manuals ot be jsut that -- information. I don't follow it blindly. Of course I read the service manual, but sometimes I don't do what it suggests. As here. If the PSU failed, you cna be sure I'd have a go at fixing it (and lack of a scheamtic doens't always make repari impossible...) [In much the same way, while I reer to many modern service manauls as 'boardswapepr guides', I do read them if theyr'e available. I am not going to start swapping boards, but I might was sell get all the informatio nI can before I dive in with the 'scope. Right... -tony

Assistive Listening Suystems are ALSO 72MHz FM, although many of them are now moving to 216MHz

We don't actually know what version of the CoCo 2 the OP has/ We're assuming it's the US version. There was a version sold over here (UK) with PAL encoded video and a UHF modulator on channel 36 (I forget the carrier frequency). There may well be other national versions though (it wouldn't suprise me at all if a PAL versio nwitha Aa VHF modualtor was made). The CoCo 3 was never sold over here, but according to the service manual there was an Australian version with PAL encoded video (but a VHF modulator). This machine hs a composite output of coruse. AFAIK from reading hte manuals, the US CoCOs have a VHF modulator switchable (esternal swithc on the rear of the machine) to channel 3 or 4.. The outptu is an RCA phone socket. If you made no conenction to the RF output socket of a CoCo or the 5 pin DIN vidoe ouptu (composite video and +5V) of a model 1, how ever did you vieww the output of these machines? -tony

On 14 Dec 2011, at 3:49 PM, David Riley wrote: The original (1938 - 1940) allocation was 18 channels with channel one at 44-50MHz and 19 at 288-294MHz. Channel 19 vanished in the 1940-1946 allocation with the remaining frequencies shifting around; channels 14 and up vanished in the 1946-1948 allocation (which again saw frequencies juggled about). In the '46-'48 period things started to go sideways; the existing channels (save for channel six) were shared with fixed and land mobile services; to mitigate interference the FCC had depended on VHF frequencies not propagating over the horizon but in practice they did so readily; in addition responding to pressure for more stations the FCC had reduced the separation distance between stations to 80 miles. In May 1949 the FCC ruled that television could no longer share frequencies with fixed and mobile services and that the 72 to 76 MHz band could be used only for fixed radio services, all of which lead to the issue of where the mobile services could go -- which ended up being one of the existing television channels. While the television industry was none to thrilled to lose a channel they felt that 12 clear channels were preferable to 12 shared channels. The ARRL had actually proposed that channel two be dropped so that the second harmonic of the 28-29.7MHz amateur band wouldn't cause interference, but the industry elected to ditch channel one because FCC regs held that channel one could only be used for community service with a 1KW restriction while other channels were permitted 50KW. -- Dr. Christian Kennedy chris at mainecoon.com AF6AP http://www.mainecoon.com PGP KeyID 108DAB97 PGP fingerprint: 4E99 10B6 7253 B048 6685 6CBC 55E1 20A3 108D AB97 "Mr. McKittrick, after careful consideration..."

Fred Cisin wrote: [...] That could be, although I thought it was the other way around, with the four-pin header of the Apple leading to the use of four pin connectors on modulators for home computers.

On 14 Dec 2011 at 19:47, William Donzelli wrote: A very ugly story goes along with this. Edwin Armstrong had started his Yankee FM radio netowrk just before WWII and FM broadcasters had been allocated use of the 42-50MHz band for their use. (You can still find the occasional rare pre-war FM receiver with those frequencies). "General" David Sarnoff of RCA at first didn't understand what FM was (he thought it was some sort of a filter on an AM radio) and then became alarmed when the relatively noise- and interference-free FM radio began gathering popularity. Sarnoff decided (and got the FCC to approve) that using FM as the audio portion of the NTSC signal was best for the fledgling TV industry. Sarnoff offered Armstrong $1 million for non-exclusive license for FM. When Armstrong refused, Sarnoff got angry and refused to pay any fees at all, and got other broadcasters to go along with RCA. Armstrong, initially a wealthy man, was worn down by RCA's bevy of lawyers and endless appeals and broken financially. He committed suicide and Sarnoff offered his widow $1 million to settle claims. Largely due to Sarnoff's vindictiveness and influence with the postwar FCC, the prewar FM band was moved to 88-108 MHz and TV channel 1 designated as the new owner of the old FM band. This, of course, made all of the receivers sold by Armstrong useless. Channel 1 proved to be less desirable than other higher-frequency channels, due in part to the better long-distance propogation characteristics, resulting in more interference. Technical innovation the American way--racketeering, legal maneuvers and dirty tricks. My uncle used to have an old Stromberg-Carlson set with the two-band continuous tuner that would tune Channel 1. --Chuck

The military also could use the 42-50 Mhz band, as part of their VHF FM squad radio band, as seen in the zillions of AN/PRC-6 and AN/PRC-10 sets. They pretty much grabbed the band during World War 2, when their really was no commercial television, and they did not want to give it back. -- Will

In most cases the modulator was a bought-in module (one popular brand, at least over here was Astec). IIRC there was a pin on the modulator to select channel 3 of 4 (it was tied to one of the supply lines for one of the channels, left open for the other I think), It's not supring that many devices that used such modualtors also had the swithc connected to this pin. Over here, the common modualtors did not have a channel select input. They were noramlly pre-tuned for our UHF channel 36,. It was possible to tweak them onto other channels by adjusting one of the cores. This is OK for comptuer and the like, where the computer is the only thing conencted to the TV aerial input at the tiem ,but VCRs, of course, also pass on the bradcast channels. So the output of a VCR had to be tunable to avoid interfering with said boradcast channels, often there was n external tweaker for this. THe later VCRs ,adn things like DVD recorders (if they support RF output) have this configurable on a setup menu. I sem ot rememebr that some US TVs have a balanced 300 ohm aerial input, and that this boc is also a Balun (the modulator output is always unbalanced, 75 Ohm). We used ot haev VHF television channels, they were used for the alas long-dead System A 405 line system. Channels 1-5 were 'band 1' and were used for the BBC transmitters (there was only one BBC programme at a given tume, all the transmitters transmitted the smae thing). Channels 6 to 13 (IRIC) were Band 3, used for the independant television (again, only one programme -- that's right, you had a choice of 2 things to wath). Band 2 was the FM radio broadcast band (88 to 108MHz ro so). The UHF channels are (soon to be 'were') used for the 625 lin Sysmte I transm,issions. Originally, the only thing here weas a second BBC channel (different programmes), the 405 line programems were not duplciared here. This led to 'dual standard' TV sets, whcih could be switched ot receive either. On the groudns that the line frequency was differnet, the transmisison frequency was differnet (UHF or VHF), the video moulation polarity was reversed, and that the sound o nthe VHF transmissions was AM and on the UHF transmisison FM, this meant a lot of switching! LAter on, the 405 line tranmssions were duplciated on 625 lines, so all you needed asa 625 line set. Ther never was colour on the 405 line broadcasts. This meand that for a time, only BBC2 was in colour. Of course osme of the early colour TVs could receive 405 line transmissions (in monochrome, of course). Those sets were nto simple... Somewher I ahve a list of the UK channel numbers and their frequencies... -tony

On Wed, 21 Dec 2011, Andrew Burton wrote: IMO the channels and their frequencies are the same, at least on the continent ;-) That's nothing but a simple DVB-T receiver, isn't it? Christian

On Wed, 14 Dec 2011, Tony Duell wrote: When I bought my first TRS80, it was available for $600 with monitor and cassette, or $400 without monitor nor cassette. The store manager, in spite of it being the first one that had come in, was willing to commit that if I were to be unsuccessful, then I could but the monitor by itself for $200 (I would still be short the cassette (another $50)). I had a Sony 11" TV/monitor (same as sold for use with both CV and AV series VTRs), with UHF connectors, a "Honda" connector, and both UHF and VHF knobs broken off - I have no idea whether the tuner in it worked. In both cases, I WAITED UNTIL I GOT HOME before I opened the computer case. (I'm not a hardware person) Then I connected clip leads from where I thought the composite video was to a composite monitor. Once I confirmed that there was, indeed, usable composite there, I drilled a hole, and soldered in an RCA jack. Therefore, the original CONNECTORS (but not the signals nor case) were virgin when I eventually parted with the machines. Later, Joe Garner (Elcompco) used my machine for testing the prototypes of his mod board for reverse video (controlled by port 254) Later, I was given another TRS80, WITH the stock monitor. There was an aweful lot of empty space where the tuner would have been in that RCA based TV turned monitor. (One of THAT model RCA TVs was appropriately in the background on Al Bundy's kitchen counter) So, I cut a large rectangular hole in the front of the monitor case and mounted a full height 5.25" (Tandon TM100-1) drive and power supply to the right of the CRT. I added some mu-metal (sp?) around it. But the MOST important modification that I made to my model I was putting some nut-serts into the base and bolting the CPU and EI (and an outlet strip) to a piece of plywood so that the cable didn't flex (and a small notch in the front of the EI for the CPU power cord without excess cables flopping around) I never got around to mounting a DB25 and solidly mounting the RS232 (_RADIO_ _SHACK_ 232). -- Grumpy Ol' Fred cisin at xenosoft.com

On Thu, 15 Dec 2011, Tony Duell wrote: Because I had some Glyptol (tamper-evident paint), to re-instate the warranty :-) Later, in order to get some of the free "upgrades" (mostly related to CPU/EI cabling), I repainted the screw. So long as we provided him with schematics of the mods, the local RS "tech" was willing to look at the paint on the screw and declare the machine to have "never been tampered with", in spite of after market numeric pad, add-in board for reverse video, lower case, a few additional keys, etc. "Since the screw was painted, any mods must have been done "boat in a bottle" style, which is not prohibited by twe warranty" I wanted to see what I was connecting to, didn't have the manual yet, I didn't have any 5-pin DINs, the local electronics surplus "Electronics Etc" was out of them!, and by that time, I was committed, and I knew that I wanted UHF or RCA for the connector. I did poke wires into the cassette 5 pin DIN probably not one of my best ideas, but it did seem to work reliably! yes -- Grumpy Ol' Fred cisin at xenosoft.com

On Fri, 16 Dec 2011, Tony Duell wrote: Couldn't get it separately until months later. Around here, IBM didn't sell that cable! 26-1401? (Or was that my highschool gym locker?)

[suspect remembrance of RS part number for cassette cable for TRS80 (also IBM 5150] On Fri, 16 Dec 2011, Charlie Carothers wrote: or an 026 interfaced to a IBM 1401 (or the 1401 emulator on a 1620) :-) 40 years ago, at NASA GSFC NSSDC (Bldg 26), I spent some time toiling over a Gerber data digitizer. Line up the crosshairs using the big etch-a-sketch knobs, stomp on the foot pedal, and the 026 would punch two 3 digit numbers. I have NO idea what the interface actually consisted of. At the other end of the room, and probably NOT connected to it, were a 7094 and a 360/30; in other buildings were several 360/9x

On Wed, 14 Dec 2011, Fred Cisin wrote: You can cable anything you like. If that will work is another question ;-) Seriously, the OP should just a VCR as a receiver/demodulator and feed the (C)VBS signal into an appropriate monitor (some modern flat panel displays have an RCA and/or S-Video input; or just use a video monitor, or better: just buy (or get for free) an old TV). The whole discussion is on the niveau of saying "I don't need electricity, but I want to use my electric toaster. What can I do?". BTW: NTSC is a colour encoding system and has nothing to do with TV channel frequencies. Christian

On Dec 15, 2011, at 5:07 AM, Christian Corti wrote: Indeed, though it is often used (somewhat coloquially, I guess) to refer to the various frequency allocations per country, a la http://hamradio.arc.nasa.gov/ntscfreq.html. Perhaps that's incorrect usage. - Dave

On Thu, 15 Dec 2011, Chuck Guzis wrote: Never Twice the Same Color (as opposed to Picture Always Lousy, and what DOES SECAM stand for?) I've been using "almost-NTSC" to refer to the not-quite-meeting-standards entire TV encoding protocol used by USA "home" computers' output for display by ordinary USA analog TV sets. Sometimes subdivided into "almost-NTSC RF" and "almost-NTSC composite" (should be called "baseband"?) Such usage is presumably wrong, and probably almost as offensive to those who know better as calling ST506/ST412 compatible drives, "MFM drives". What SHOULD such be called? (any answer that calls for an appellation using a complete description longer than a line of text will be thoroughly ignored :-) -- Grumpy Ol' Fred cisin at xenosoft.com

At 12:48 PM 12/15/2011, Fred Cisin wrote: Those terms sound pretty good to me. I've tried to think of what else it might've been called informally... certainly just "RF" but maybe "RF composite"? Wikipedia didn't offer any suggestions. - John

This reminds me of a related question that I dont know the answer to. The terms'PAL' and 'SECAM' refer to the method used ot encode the colour information, they do not say who designed it, or the scan rates/ number of lines used. It is, AFIAK, perfectly correct ot talk about a 525 line PAL signal, IIRC that's PAL-N But an NTSC colour signal implies not only the colour encoding, but also the scan rates (60Hz vertical, 2 way inerlacesd, 525 lines) etc. So my question is : If you use ''NTSC-like' colour encoding (phase angle is the hue, amplitude is the saturation -- think of it as being PAL without the altehrnate line flip) on a 625 line 50Hz vertical svideo signal, what do you call it? Coloquially it's often called 'NTSC 50Hz, or even NTSC-I (or NTSC-B/G) but those names are clearly wrogn if you're being pedantic about it. What is the right neam? -tony

On 15 Dec 2011, at 4:22 PM, Chuck Guzis wrote: Technically it's not obsolete; translators, low power stations and class A stations are still authorized to broadcast analog; I don't believe the FCC has specified a cut-off date for such stations. A quick look at the FCC says that there's 439 class A UHF, 76 class A VHF, 3043 UHF translators, 1411 VHF translators, 1656 UHF low power and 516 VHF low power stations currently licensed for broadcast service. Some of those may be digital and some may not currently be on the air. If I try to refine it much more I'll end up spending half the day lost in the ULS :P -- Dr. Christian Kennedy chris at mainecoon.com AF6AP http://www.mainecoon.com PGP KeyID 108DAB97 PGP fingerprint: 4E99 10B6 7253 B048 6685 6CBC 55E1 20A3 108D AB97 "Mr. McKittrick, after careful consideration..."

Yes, OK, it may be obsolete _for broadcasting_, but there must sitll be stuff around that uses iy. This is classiccmp after all, I am sure there are similar people who messaround with old TV and video equipment (I know for a fact there are people ove rhere to run 405 line System A sets, for all there have been no system A broadcasts for 30 years or so). In any case, I feel there should be a way of describing such a signal, even if nobody is currently using it. -tony

On 16 Dec 2011, at 4:20 PM, Chuck Guzis wrote: [snip] I suspect you're right about that. Amen to that, brother. -- Dr. Christian Kennedy chris at mainecoon.com AF6AP http://www.mainecoon.com PGP KeyID 108DAB97 PGP fingerprint: 4E99 10B6 7253 B048 6685 6CBC 55E1 20A3 108D AB97 "Mr. McKittrick, after careful consideration..."

On Thu, 15 Dec 2011, Christian Corti wrote: BTDT My recommendation is/was the "Digital Prism" (~$50 7" HDTV that can do analog, (and has very good CC display)) THAT, and my new Philips 19" are the first TVs that I have ever owned with working internal tuners - I ALWAYS used VCRs and/or cable boxes, and in the case of a cable box with RF out, followed by a CC converter that included RF in and "composite" out. But, to THIS group, that is just a "challenge" Howzbout: heat ceramic tiles in a fire, then put them into the crumb tray? I conflated NTSC with the entire signal, but did NOT use that to refer to the channel/frequency. i.e. "almost-NTSC on USA channel 3" I was under the [mis]impression that color encoding was but one part of the standard. Sorry. -- Grumpy Ol' Fred cisin at xenosoft.com

On Thu, 15 Dec 2011, Christian Corti wrote: Should I admit that my first 5.25" drive interface to 8" drive cabling was based on a solderless plug-board?

On Thu, 15 Dec 2011, Tony Duell wrote: Probably I'm wrong. I was under the impression that the only purpose of the NTSC was to define a new colour standard (Never The Same Colour). Whatever, I don't know of anything they did afterwards. Christian

Christian Kennedy wrote: It would have been better (IMHO) to shift the sound subcarrier frequency by 0.1%, and keep the scan rate the same. None of the existing receiving equipment (televisions) of the day had a precise enough sound demodulator that this would have made any difference whatsoever. I told that the FCC wouldn't let them shift the sound carrier, but I have no idea why. The result is the 0.1% shift in the scan rate, which resulted in the need for really awkward and inconvenient stuff like drop-frame time code. Nevertheless, I think that RCA and the second NTSC did some of the most amazing and underappreciated engineering of the twentieth century. Eric

On 16 Dec 2011 at 11:19, Christian Kennedy wrote: Why? Do you think that development of the tri-color CRT would have been prevented by adoption of the field-sequential color system? Instead, we had to put up with terrible color for decades. I remember the CBS color system--some CBS-branded sets of the time even had octal (or dodecar) sockets at the back of the chassis for the colorwheel adapter. Compared to the green skin tones of the RCA system, the CBS color rendition was superb. Europe had the right idea--instead of rushing something half-baked to market. Granted, I saw only demonstrations of the CBS color system, but I remember that the local electronics surplus dealer had big wooden crates full of now-useless color wheels. I'm sorry that I didn't pick up a few. --Chuck

Christian Corti wrote: That was the second NTSC, in the early 1950s. The first one, in the 1940s, did the monochrome standard, and probably was involved in every aspect of defining the way television broadcasting worked, including both baseband and modulation. I don't think they did anything afterwards, but I could be wrong. Apparently the two NTSCs published many volumes of reports, but I haven't been able to track down copies of any of them. There is a book published recently that reprints some of the highlights. Eric

On 16 Dec 2011, at 9:50 AM, Fred Cisin wrote: If you say RS-170a most people will know what you're trying to say; if you want to be pedantic it's System M with NTSC color or more simply NTSC-M. -- Dr. Christian Kennedy chris at mainecoon.com AF6AP http://www.mainecoon.com PGP KeyID 108DAB97 PGP fingerprint: 4E99 10B6 7253 B048 6685 6CBC 55E1 20A3 108D AB97 "Mr. McKittrick, after careful consideration..."

I understood from Tony a CRT monitor should just work. I was asking him if I understood him correctly. From your post, it seems I didn't! -----Original Message----- From: David Riley <fraveydank at gmail.com> Sender: cctalk-bounces at classiccmp.org Date: Tue, 13 Dec 2011 09:38:04 To: General Discussion: On-Topic and Off-Topic Posts<cctalk at classiccmp.org> Reply-To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Subject: Re: TV -> D-Sub converter possible? On Dec 13, 2011, at 7:04 AM, vintagecoder at aol.com wrote: Not to resuscitate the thread unnecessarily, but you do still need something to take the composite video (modulated by an RF carrier or not) and turn it into RGB + sync for the monitor (not the simplest of processes, but as mentioned, there are quite a few devices to do so). Not sure if that's what you meant or not. - Dave

Thanks a lot. I can't answer your question on PAL on the COCO II since mine is in storage. Appreciate all the good info, I'll ask again when I have the equipment handy. -----Original Message----- From: David Riley <fraveydank at gmail.com> Sender: cctalk-bounces at classiccmp.org Date: Tue, 13 Dec 2011 11:07:25 To: General Discussion: On-Topic and Off-Topic Posts<cctalk at classiccmp.org> Reply-To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> Subject: Re: TV -> D-Sub converter possible? On Dec 13, 2011, at 9:58 AM, Vintage Coder wrote: I think he probably meant once you'd converted it from RF/composite, it would work. A composite signal is a mashed-up luma/chroma (brightness/color) signal, which is in turn a mashed-up YPbPr (brightness/difference from blue/difference from red) signal. Once you get back to YPbPr, you need to do a transform to turn that into RGB values, which is what a CRT monitor will understand. You also need to separate out the vertical and horizontal sync signals, because a CRT expects to get them separately (well, most do; there are monitors which expect it to be superimposed on the green signal). It's a non-trivial job to turn a composite signal into RGB, which is what a CRT (or a DVI monitor, which expects the same thing but digitally) wants to see. A TV card will do that for you and DMA the RGB data straight into your computer's RAM, or you can get a converter box that does it all and blasts it out to VGA or HDMI (which should convert to HDMI through a very cheap passive adaptor, since HDMI is inter-compatible with DVI). Either way, there's going to need to be something in between. I'm also not familiar with the CoCo line; did they ever make a PAL version? If not, it wouldn't be useful to you to have a TV (well, not a UK TV, anyway) because it wouldn't work. Most TV cards (especially if you're not using the god-awful manufacturer's provided software) will tune to NTSC, PAL and SECAM and successfully decode all three (though SECAM is left out often enough). You'll want to make sure you get a card that can tune to US frequencies, though; the tuners are often a bolt-on thing which can vary by manufacturer. I can highly recommend the ATI Tv Wonder Pro (http://www.amazon.com/ATI-Technologies-Wonder-PCI-NTSC-100-703138/dp/B0000C…; it may be available in your flavor of Amazon for a similar price). This particular one tunes NTSC, so it will pick up an NTSC CoCo just fine. From my recollection, only the tuner is restricted to NTSC (the frequency bands tend to be the issue there), so you should be able to take in PAL/SECAM input sources on the other input connector if you should ever need to do so. - Dave

I thought your original message did vie the option of 'building' the converters Ah, OK... It's up to you. The mod should be reversable, but it wil involve opening the case which would damage the sticekr over one of the screws. You may not wnat to do that. No, the CoCO 2 (and origianl CoCo) do not haev composite outputs. The CoCo 3 does, BTW. I was suggestign modifying the CoCo to extract the compositie signal. No. As I said in another message tonight, the most important thing is the scan rate, If you haev a CRT monitor that can do TV rates (not a workstation monitor or a VGA monitor or..) then you can probably get it to work with the CoCo, but it might involve modifying one or both devices. What 'death rays'??? -tony

Thank you.