On 1 Nov 2006 at 20:53, Richard A. Cini wrote: There were several of these types of monitors. Mitsubishi had a few DiamondScan models that had RGB BNC connectors, as well as TTL and analogue connections--and there were a few switches on the rear of the unit to select what was what, along with different adapter cables. I still have one that I use with a PAL VHS VCR and a decoder to watch my old tapes of the Edinburgh Tattoo... Cheers, Chuck

--- Jim Leonard <trixter at oldskool.org> wrote: I seem to remember something about RS-170 style video being 1 volt peak to peak or .7 volts peak. "P2P" seems to indicate a signal that is half negative going? Would have to do more research, but if not, maybe a resistor would do the job (i.e "convert" 5 volts to a correspodingly "high" analog voltage, as mentioned). The older broadcast monitors were designated RS-170 (those with seperate color inputs) I do believe. Maybe modern VGA signals and whatnot are also compatible. One problem...what do you do with the Intensity input (older TTL monitors are not RGB, they're RGBI). Indeed it might. Why don't you give it a try and let us know Jim LOL LOL. Keep the ol' fire extinguisher nearby though. http://www.highway.net.au/parts/converters/1488.html) That thing seems to do it all (for CGA freqs anyway). But double scanning and voltage conversion are 2 separate issues. I ain't spending $141 for such a thing anytime soon. If you can use the divide and conquer method, figuring out how to double all the 2000's outputs (yielding 800 line, in terms of frequency, video), then do the voltage conversion. Then pump it all into yer 19" KDS you bought for 80 bucks at Walmart. All of the 2000 outputs are TTL level signals (hmm sync too? But at least they're "digital", or maybe close to square waves anyway). So it's doubled sync signals would be compatible with a new monitor, then there's the voltage conversion. Then there's the Intensity issue. Oi ____________________________________________________________________________________ Cheap Talk? Check out Yahoo! Messenger's low PC-to-Phone call rates (http://voice.yahoo.com)

--- Patrick Finnegan <pat at computer-refuge.org> wrote: Well that's encouraging. I was thinking in terms of sine waves and such, which have a peak to peak voltage, and in that case, half of the cycle is below ground. I was under the impression that measuring such a signals "peak" voltage was an rms value, but I guess I botched that up too :) So RS-170 has nothing to do with the amplitude of the signals? Or should I ask to specify something as RS-170 compatible/compliant. ____________________________________________________________________________________ Access over 1 million songs - Yahoo! Music Unlimited (http://music.yahoo.com/unlimited)

--- Patrick Finnegan <pat at computer-refuge.org> wrote: I left out the most important part, are new monitors RS-170 compliant? But never mind, I'll look it up. So many choices. And you do realize you'r implying that perhaps I should be working for Google, given I'm such an effective researcher... ____________________________________________________________________________________ Want to start your own business? Learn how on Yahoo! Small Business (http://smallbusiness.yahoo.com)

At 03:04 PM 11/2/2006, Chris M wrote: Wasn't there a lot of slop in the supposedly RS-170 that many 70s-80s computers were generating? There's the spec, and then there's the just-good-enough signal they'd generate by any hack that looked good on the expected type and quality of output monitor. - John

What slop factor are we talking about? ____________________________________________________________________________________ Cheap Talk? Check out Yahoo! Messenger's low PC-to-Phone call rates (http://voice.yahoo.com)

On 11/2/06, Jim Leonard <trixter at oldskool.org> wrote: It depends on the level of precision you require and if the target VGA monitor handles RGBI scan frequencies. So... start with a multisync that can handle the requisite sync frequency from your RBGI-equipped CPU. Something like an old NEC-3D can sync down to the NTSC range (~15KHz horizontal). You might or might not need to invert hsync and vsync (I did to attach an Amiga to an RGBI monitor). Now that you have sync taken care of, you can worry about R, G, and B. In essence, an older VGA monitor is expecting an analog signal on each of 3 color pins, but RGBI is a 4-bit digital interface. It shouldn't be hard to use sets of resistors to make a simple, if imprecise, DAC to turn 4 digital bits into 16 analog levels on the 3 color pins (the "I" bit controls intensity of all three channels simultaneously, such that if your RGBI pattern is 1111 vs 1110, it's white vs gray (I can't remember if "I asserted" means full intensity or half, but worst case, if you have it backwards, it's not hard to invert a TTL signal to flip the sense of the "I" bit before it goes into your "DAC"). Worst case, you could start by ignoring "I" and have an 8-color output TTL levels down to the high end of what the VGA monitor is expecting (0.7VDC == max intensity?) If you want to be able to tweak the color balance, one could just use 3 variable resistors that can span the range near the value you would have used for each fixed resistor. I haven't tried to do this myself, so I can't supply specific values, but an oscilloscope would be a handy tool if you wanted to build a simple 8-color (no "I") resistor-based TTL->VGA analog "DAC" - get your sync issues solved first, then put a variable resistor on, say, Green first, then get the computer to display a green screen, then set the resistor so you have approximately 0.7V showing as the peak voltage on the green line. Repeat for Red and Blue. Voila... digital RGB on an analog VGA monitor. -ethan

On 11/3/06, Chris M <chrism3667 at yahoo.com> wrote: I did miss the part about a "modern monitor". Sorry about that. You _would_ need some sort of scan doubler to get around that issue. Internal scan doublers were common with Amigas since the custom chipset was very NTSC or PAL-centric, not VGA-centric. The A3000 had one built-in, and there were several options for the video slot on an A2000. ISTR the price in the day for a scan doubler card was at least $150 - they entirely buffered a frame in local RAM and squirted it out at 31.5KHz on a VGA connector. Effective, but complicated. Ah... didn't know the T2K was only 8 colors. Naturally. I was simply thinking that the OP needed _some_ color monitor and might have access to a multisync that could scan to lower rates than VGA. I did just remember there is one "exception" to the simple case I outlined... brown. We had a discussion here some months ago about how one of the IBM color monitors "knew" brown was funny and had some compensation circuit. I'll just restate that my suggestion is an approximation, and you might or might not be satisfied with the results - presuming you can locate an older multisync monitor in the first place. The general solution (using a 2006-era monitor) is likely to be an expensive route. -ethan

--- Ethan Dicks <ethan.dicks at gmail.com> wrote: I also remember a product called a "flicke fixer", which in essence I guess was more of a field doubler then a scan-line doubler. Would still preclude the use of a stock 'Miga monitor I guess too, since the interlaced modes were the highest res (hmm but this would mean a single monitor could do both non- and interlaced video). Uy Nah, the 2K never did brown (nor did the bulk of non IBM monitors IIUC). But if that big brown donkey game was written in BASIC, it could be ported to the 2K easily. hmmmm Shouldn't be very expensive at all if the methods mentioned here are applicable. Of course there's the scan doubling. That also doesn't sound too daunting, and if I could ever get a hold of a Princeton Scan Doubler, it's likely to become a whole lot easier. ____________________________________________________________________________________ Everyone is raving about the all-new Yahoo! Mail (http://advision.webevents.yahoo.com/mailbeta/)

THe 'few resisotrs' will turn a CGA digital signal into an analogue RGB signal at the same scan rates. For example, you could feed it into the RGB intputs on a TV SCART socket. What the 'few resistors' don't do is convert the 15.7kHz CGA signal into a 31.2kHz VGA signal. If your display can handle the lower scan rates, then fine. If not, it's not going to work. -tony

On 2 Nov 2006 at 12:47, Chris M wrote: If that's the 1302, I've got the service manual and schematics. It'll do VGA, but not anything beyond 800x600. I bought mine at WCCF sometime in the 80's and paid about $600 for it and thought I was getting a real bargain. The thing had an unbelieveably thick IEC power cord. I mostly used it with the Everex Micro Enhancer EGA cards and briefly with a Paradise VGA until I went to surplus fixed-frequency workstation monitors. Still have the EGA cards, but heaven only knows why. Times have changed... Cheers, Chuck

On Thu, 2 Nov 2006 13:19:50 -0800 (PST), Chris M wrote: ....... I used mine to evaluate autocad drivers and video cards. Any EGA card with a second clock or an external clock board added could go 640x480 and many could do 800x600 with a good Multiscan montor. Just my 2 cents Bob

On 2 Nov 2006 at 13:19, Chris M wrote: This was very pre-VGA. However, the monitor could take either analogue RGB or TTL RGBI levels. The fact that it worked with VGA when it came out was pretty much happy coincidence. This was not unusual on multisync monitors of that era. There was (maybe "is") an outfit that offered ISA and PCI cards with modified firmware to handle the sync issues. You just took a 15- pin to 5-BNC cable, set a jumper on the board and you were in business. I just gave away a 20" Sony with a Mirage card recently. I think it used a Tsenglabs ET6000 chipset. Earlier Mirage cards used one of the S3 chipsets. The cards would also work with RGB+HV separate sync monitors as well as SOG. I've still got a 17" HP/Sony monitor stashed away. Cheers, Chuck

This thread summarizes the issue... http://www.vintage-computer.com/vcforum/showthread.php?t=4554 Indeed, a series of DACs would be needed to convert the T2K TTL to analog for modern monitors but it doesn't solve the scanning frequency. I get there's an app note on Analog Devices or National's Web sites... Rich Rich Cini Collector of classic computers Lead engineer, Altair32 Emulator Web site: http://highgate.comm.sfu.ca/~rcini/classiccmp/ Web site: http://www.altair32.com/ /***************************************************/ -----Original Message----- From: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Chris M Sent: Wednesday, November 01, 2006 8:31 PM To: General Discussion: On-Topic and Off-Topic Posts Subject: Re: New monitors on old machines --- "Richard A. Cini" <rcini at optonline.net> wrote: Sorry dude. The T2K and most things from that era output ttl (digital) color information. Modern multisyncs require analog input. Ain't happening. Besides, modern multisyncs will probably only sync down to original "low-res" VGA hsync frequencies (31.5khz). The 2K outputs 24-26khz, I don't remember exactly. There are a number of hurdles to overcome to get something like that working with a modern monitor. As a side note, I've requested info on the scan doubler made by Princeton. It allowed you to use a CGA card with one of their monitors that took ~400 lines of res like a 2K. I guess it was a good idea for people who had a CGA card, intended to upgrade it at some point, but avoid obsolescence w/the monitor. The reason I decided on buying a multisync right off. I guess I could contact Princeton... And the other thing that would be nice is a way to convert a ttl signal to analog. Doesn't sound too hard to me... ____________________________________________________________________________ ________ We have the perfect Group for you. Check out the handy changes to Yahoo! Groups (http://groups.yahoo.com)