Re: 8-bit Computer TV Channel Use
I just noticed that the Si2137 and Si2177 tuners are now marked as factory special order and Mouser, where they were previously just marked New at Mouser. So my guess that those parts are a leftover tray with questionable future availability might be unpleasantly accurate. I'm still interested in pursuing a cheap tuner design to see if it goes anywhere. Even if it turns out that some existing composite to HDMI converter satisfies everybody, I think there would be interest in a small, inexpensive standalone RF demod to get composite video out of vintage home machines without internal mods, and Crazy Cat Lady could morph into that. Maybe it would involve custom hardware, maybe it would be a TV tuner dongle operated in SDR mode plugged into a Beaglebone with custom software, maybe it would be a general purpose SDR design that happens to be well-suited for video demod... figuring that out is the fun part for me. -- Mark J. Blair, NF6X n...@nf6x.net http://www.nf6x.net/
Re: 8-bit Computer TV Channel Use
On 2015-06-02 11:47, Mark J. Blair wrote: After that, you will need something fairly hefty at the start to find the characteristics of the signal and align the sampling. Then you just need to track clock drift and adjust a VCXO. I was wondering whether I could get away with tracking the clock drift digitally rather than closing an analog PLL. What do you think? For the general ADC route, I would put a PLL/clock synth on the board in-case you have gross alignment errors on the incoming signal. The input should be a multiple of 13.5 but you never know with clock short-cuts on early systems. It's been a while since I've looked at the Zynq PLLs, but usually they aren't designed for large bit depth M and Ns. You will need one anyway to generate a 12.288 for audio and the different output dot clocks. I've used TI CDCE906 and IDT's VersaClock IIIs for this in other projects. A VCXO is probably the simplest choice for clock recovery. Simple PWM and RC filter to the tracking pin will allow you to slew the clock 150ppm or so. As far as ZynQ, I would throw up a few warnings about the 300 MHz DLL drop-out point on DDR3 and difficulty of routing. However I'm reminded of the Zed board and their placement of by-pass caps in a pattern that looked 'pretty'. Certainly not a beginner project, but you don't sound like one. If you wanted to start with Parallella boards instead, I have a couple trays of the SamTech mating connectors. I can send some your way. For SoC, it depends on the power you need to look at the signal. If I were faced with the requirements you have created, I would start looking at the Atmel SAMV7x line. The EVMs are starting to ship publicly and it's the first to market for the ARM M7/Pelican core. It's has more DSP performance in a small micro than most DSPs a generation ago. With OTG and integrated highspeed USB PHYs, you could also ship the frame buffer updates to a PC and support USB stick firmware update. Might be a nice alternate solution to HDMI scaling. And it's super cheap. A number of smaller FPGAs might do the trick depending on how complex your RTL pipe-line is. The usual suspects, Spartan 6, MachXO2, and the new MAX10 from Altera. -Alan
Re: 8-bit Computer TV Channel Use
On Jun 1, 2015, at 17:43, Chris Osborn fozzt...@fozztexx.com wrote: The color on the hi-res screens looks pretty good, but the vertical lines through the blocks on the lo-res screens isn’t quite right. The bottom 4 lines of text having color bleeding is normal, even on an Apple color composite monitor. The monochrome 80 column screen looks pretty good too. Well, you're right! The text looks like crap on an analog CRT, too. I updated my blog post with a few more pictures. Now I'm even more curious about the reports I've heard about having trouble with video conversion, since the first cheap converter I tried seemed to work OK with an Apple //c. Of course, it still lacks a tuner for the TV-connected computers, but I got the impression that the Apple II series was especially picky about its video converters. Maybe there's a different program I should try running that does weird stuff with video modes, like some game with particularly interesting graphics? I'm also interested in seeing what the converter will do with composite video tapped out from a Color Computer's innards. I seem to recall that it had some screwy video modes that required the user to keep hitting the reset button until the colors weren't swapped. -- Mark J. Blair, NF6X n...@nf6x.net http://www.nf6x.net/
Re: 8-bit Computer TV Channel Use
On Jun 1, 2015, at 17:43, Chris Osborn fozzt...@fozztexx.com wrote: Do you happen to have an old CRT TV around with composite input that you can hook up and compare to, just for yourself? I’ve got an Amdek Color I and Apple IIc Color Composite here that I’ll try to take some sample pictures of. Hmm, I should be able to try it out with a Commodore 1080 monitor. -- Mark J. Blair, NF6X n...@nf6x.net http://www.nf6x.net/
Re: 8-bit Computer TV Channel Use
On Jun 1, 2015, at 5:24 PM, Mark J. Blair n...@nf6x.net wrote: I received the $19 composite video to HDMI converter that I ordered from Amazon, tested it a bit with my Apple //c, and posted pictures of the results here: http://www.nf6x.net/2015/06/cheap-hdmi-converter-with-apple-c/ Text modes worked pretty well, but graphic modes had a lot of colored fringes and distortion. I've only ever used Apple II series machines with monochrome displays, so I don't know how much better or worse the original analog CRT displays of the day might have performed. Do the Apple II experts have any feedback to share? The color on the hi-res screens looks pretty good, but the vertical lines through the blocks on the lo-res screens isn’t quite right. The bottom 4 lines of text having color bleeding is normal, even on an Apple color composite monitor. The monochrome 80 column screen looks pretty good too. Do you happen to have an old CRT TV around with composite input that you can hook up and compare to, just for yourself? I’ve got an Amdek Color I and Apple IIc Color Composite here that I’ll try to take some sample pictures of. -- Follow me on twitter: @FozzTexx Check out my blog: http://insentricity.com
Re: 8-bit Computer TV Channel Use
On Jun 1, 2015, at 19:31, Chris Osborn fozzt...@fozztexx.com wrote: This one looks exactly like yours, but it’s even cheaper! I wonder if it’s the same? http://www.amazon.com/dp/B009A6PJKQ When you get it, we can compare pictures of their innards. Mine has a PCB with blue soldermask. Most of the functionality appears to be in a single QFP, probably with a central ground/heat slug based on the vias on the bottom side of the board. The top of the chip appears to have been sanded to remove the markings. -- Mark J. Blair, NF6X n...@nf6x.net http://www.nf6x.net/
Re: 8-bit Computer TV Channel Use
On Jun 1, 2015, at 7:03 PM, Mark J. Blair n...@nf6x.net wrote: Now I'm even more curious about the reports I've heard about having trouble with video conversion, since the first cheap converter I tried seemed to work OK with an Apple //c. Color is always the problem with converters. The cheap composite to VGA converter I have will show all the color as monochrome stripes. It has problems with the Apple II and the Atari 800, but works perfectly fine with the Commodore 64, since the C64 doesn’t use the same weird tricks to get color. I’ve read that sometimes they can handle the Apple II color fine, but there’s no way to distinguish which actual model you’re getting since the cases are all identical and they are sold by Chinese sellers. Most likely early ones worked and later ones don’t. A couple of times I’ve also been tempted to drag my NTSC Apple IIc ZX Spectrum with composite PAL mod down to a Best Buy and try out some small LCD TVs to see if there’s a model that can handle both. This one looks exactly like yours, but it’s even cheaper! I wonder if it’s the same? http://www.amazon.com/dp/B009A6PJKQ Heh, found another one for 3 bucks more with Prime, so I ordered it. I wonder if I have anything I can use to split the video signal out of one of my computers so I can do a side-by-side comparison. -- Follow me on twitter: @FozzTexx Check out my blog: http://insentricity.com
Re: 8-bit Computer TV Channel Use
If you do end up building a custom solution, I have a feature request :-) It would nice if the device was also a frame grabber that could, under command, snap one or more frames of the legacy video and export it over USB perhaps. This would allow us to document operation of legacy software with high quality frame grabs since persumably you'd have access to the image in a relatively good quality domain before you turned it into DVI/HDMI or whatever. Chris -- Chris Elmquist NØJCF
Re: 8-bit Computer TV Channel Use
On May 26, 2015, at 14:07 , Chris Elmquist chr...@pobox.com wrote: If you do end up building a custom solution, I have a feature request :-) It would nice if the device was also a frame grabber that could, under command, snap one or more frames of the legacy video and export it over USB perhaps. That was already on my possible-feature list! ;) If I do end up using a Zynq FPGA, then hanging things like Ethernet and/or USB OTG would be cheap to add. Those wouldn't be my first priorities to implement in firmware, but I should at least include stuff options for the connectors and PHYs on the PCB. I'm not sure yet whether I'd start with a dev board or go straight to a custom board. The Zybo board is cheap and has the cheaper Zynq chip that I'd like to target, but it lacks good physical connections for a couple of relatively high-speed DACs, and it only supports 720p HDMI output because it lacks a dedicated HDMI PHY. I could get 1080p and an FMC connector out of the much more expensive Zed Board, but it uses a larger Zynq chip that would be prohibitively expensive for this project, and if I had to build a board with an FMC connector for my analog front end then I'd already be making a board that's too advanced for me to solder up at home, so I might as well thrown down the FPGA, too, rather than spending $500 on a not-quite-right dev board. Sigh... This would allow us to document operation of legacy software with high quality frame grabs since persumably you'd have access to the image in a relatively good quality domain before you turned it into DVI/HDMI or whatever. Agreed! Grabbing some live video might also be an option, but I think that would be a smaller incremental value add than getting high quality single frame grabs. BTW, every good project deserves a good project name. I'm tentatively calling this one Crazy Cat Lady. It has a nice ring to it. -- Mark J. Blair, NF6X n...@nf6x.net http://www.nf6x.net/
Re: Monitor wanted (was Re: 8-bit Computer TV Channel Use)
a lot of monitors have been and are being junked Back when we were getting a lot in we would set xtras in the alley I hope someone got them that will treasure them. Ed# -Original Message- From: Eric Smith space...@gmail.com To: General Discussion: On-Topic and Off-Topic Posts cctalk@classiccmp.org Sent: Sat, May 23, 2015 9:15 pm Subject: Re: Monitor wanted (was Re: 8-bit Computer TV Channel Use) On 05/23/2015 04:24 PM, Eric Smith wrote: I'd like some of the REAL monitors, such as an NEC Multisync 3, that can do VGA *and* NTSC-rate analog RGB. At some point the monitor companies stopped bothering to make them handle horizontal scan rates below 30 kHz. On Sat, May 23, 2015 at 6:56 PM, Chuck Guzis ccl...@sydex.com wrote: Find an old Mitsubishi Diamondscan, say the AUM-1381A and you can pretty much do anything up to 800x600 VGA. I was given a few Mitsubishi Diamondscan CRT monitors last year, but unfortunately they're too new to support 15kHz horizontal.
Re: 8-bit Computer TV Channel Use
There are probably a fair number of TV cards in both ISA and PCI wandering about, since they're not terribly useful with the advent of digital TV (and the web). Has anyone hooked up an ordinary NTSC modulator with one of those and an 8 bit PC that relies on the peculiarities of NTSC chroma encoding? If so, how's the reception quality? --Chuck
Monitor wanted (was Re: 8-bit Computer TV Channel Use)
On Sat, May 23, 2015 at 9:36 AM, Fred Cisin ci...@xenosoft.com wrote: Would you like some of the REAL monitors? They will do all sorts of bizarre I'd like some of the REAL monitors, such as an NEC Multisync 3, that can do VGA *and* NTSC-rate analog RGB. At some point the monitor companies stopped bothering to make them handle horizontal scan rates below 30 kHz.
Re: 8-bit Computer TV Channel Use
On May 23, 2015, at 8:24 AM, Mark J. Blair n...@nf6x.net wrote: In the middle will be some FPGA to perform any necessary magic. I've been looking at a prohibitively expensive ($115) one that has enough dual-port RAM blocks to support a frame buffer. Are you on the CoCo mailing list? Have you seen the RGB2VGA by Luis Antoniosi (CoCoDemus)? I know at one point he had been tinkering with making it support composite from the Apple II. It’s semi open-source, I think there are 2 versions and the latest version is currently all closed source. https://sites.google.com/site/tandycocoloco/rgb2vga -- Follow me on twitter: @FozzTexx Check out my blog: http://insentricity.com
Re: 8-bit Computer TV Channel Use
On 2015-05-23 09:59, Jochen Kunz wrote: Advantage: - No obscure FPGA magic needed. Disadvantage: - No obscure FPGA magic needed. ? ;-)
RE: 8-bit Computer TV Channel Use
The output of a single-chip tuner might also be at IF. The Maxim part (which I will not use) outputs at 36 MHz, I think. Can't tell the output of the SiLabs part without more info. Hopefully it's either baseband or a lower IF 36MHz does sound like the standard TV IF frequency. frequency that I could sample with a cheaper ADCs for digital down-conversion. Needing to support a 36 MHz IF would probably increase ADC cost vs. using ones that just need to sample baseband or a low IF. SAW filters are also black magic, and nowadays they are TINY! Problem with TINY parts is soldering them :-). The SAW filters I used (with a conventional tuner module) were round metal cans about 0.5 in diameter with 8 pins on IIRC a 0.1 spacing. Very easy to handle. If you are designing something for others to build (even in principle, i.e. you are making it an open design) then using impossible to handle parts is a bad thing if there are alternatives. Oh yes, in the UK the sound carrier was 6MHz offset from the video carrier, in the rest of Europe the spacing was 5.5MHz. So if you want to handle sound (some computers sent their sound output over the RF output) you may need to cover both. And US NTSC puts the sound carrier at 4.5 MHz, so there's another thing in favor of using SDR techniques for some portion of the demodulation if I can't find a Magic Chip that does the work more cheaply. The chroma subcarriers are also at different frequencies in the various standards. And IIRC US NTSC uses AM sound (Europe uses FM). I think you can forget about stereo sound, since I doubt any home computer had a stereo RF modulator. Be warned that there are many versions of PAL. PAL B/G and PAL I are the ones used in Europe and the UK, and are basically compatible apart from the sound carrier offset (there are other differences, but they are unlikely to matter here). But there is also PAL M and PAL N. at least. I forget which way round they are, but both have a colour carrier around 3.58MHz. One is 625 line the other is 525 line. I think one was used for TV in South America, did any home computers there use it? I doubt you would have to support system A (405 line) or system E (819 line), both AFAIK were only ever used for monochrome signals. I can't think of a computer that would use them. At the output of this section you had composite video and line-level audio. What you do with those is up to you And that's where the fun begins! The plan is to infer what color the vintage computer was trying to display at any given pixel, with knowledge of the dirty tricks it used to get that color cheaply. Then cram that inferred pixel into the frame buffer, and convert the video format on the other side of the frame buffer. Sure. I think that is the interesting (and complex) part of the project. If you can get that right, you could even just tell users to either tap the video off at the input to the RF modulator, or use an old VCR for the tuner/IF section. Evil thought (and I have not worked this out yet). You are going to be connecting the RF signal straight from the computer to this unit. Do you really need a _tuner_? You have essentially one strongish signal. What about an untuned receiver and demodulator? At VHF totally possible, UHF might be a lot harder... -tony -- Mark J. Blair, NF6X n...@nf6x.net http://www.nf6x.net/
Re: 8-bit Computer TV Channel Use
On Sat, 23 May 2015, Mark J. Blair wrote: On May 23, 2015, at 10:28, Steven Hirsch snhir...@gmail.com wrote: On Sat, 23 May 2015, Chris Osborn wrote: I own one of just about every commercially available (and hobby) converters and precisely none of them provides a universal solution. Some give great displays from an Amiga and suck for anything else. Of my two (pricey) CVP CM-345S converters, only one provides useable display from an Apple IIGS. My GBBS-8220 can occasionally be coaxed into giving a solid display from a Color Computer 3. The list goes on... Aha! I've heard Nth-hand accounts of trouble getting vintage computers to play with video converters, but you sound like one of the folks with firsthand experience. Yes, with all the scars and credit-card activity to prove it. --
Re: 8-bit Computer TV Channel Use
On May 23, 2015, at 12:05 PM, Steven Hirsch snhir...@gmail.com wrote: That really surprises me. Mine was utterly unusable with the IIGS. The desktop (and all icons, folders, etc.) had distinct vertical bands through them. Also, lots of dot-crawl at sharp edges from what I recall. I believe mine is a knock-off clone, and not a “genuine” GBS-8200. -- Follow me on twitter: @FozzTexx Check out my blog: http://insentricity.com
Re: 8-bit Computer TV Channel Use
On May 23, 2015, at 10:28, Steven Hirsch snhir...@gmail.com wrote: On Sat, 23 May 2015, Chris Osborn wrote: On May 23, 2015, at 8:24 AM, Mark J. Blair n...@nf6x.net wrote: In the middle will be some FPGA to perform any necessary magic. I've been looking at a prohibitively expensive ($115) one that has enough dual-port RAM blocks to support a frame buffer. Getting an acceptable combination of crisp 80-column text and proper color aliasing from a converter is decidedly non-trivial. Even back in the day, I believe it involved swapping the cable between a monochrome monitor and a color one. I expect that this universal converter idea will require a way for the user to tell it whether they want color or monochrome video at the moment (and might as well let them choose what color phosphor to emulate). That way, an Apple II user who wishes to use modern displays could switch between 80 column mono mode for text or color mode for graphics, without swapping cables or displays. I own one of just about every commercially available (and hobby) converters and precisely none of them provides a universal solution. Some give great displays from an Amiga and suck for anything else. Of my two (pricey) CVP CM-345S converters, only one provides useable display from an Apple IIGS. My GBBS-8220 can occasionally be coaxed into giving a solid display from a Color Computer 3. The list goes on... Aha! I've heard Nth-hand accounts of trouble getting vintage computers to play with video converters, but you sound like one of the folks with firsthand experience. If transparent, tweak-free emulation of a classic CRT display were easily doable, it would have been done by now. Agreed! I envision that the converter should have some sort of smarts to help it figure out what sort of input it sees, but even in the ideal case it'll probably need some capability for user tweaking or mode switching for corner cases. On May 23, 2015, at 10:41, tony duell a...@p850ug1.demon.co.uk wrote: Problem with TINY parts is soldering them :-). The SAW filters I used (with a conventional tuner module) were round metal cans about 0.5 in diameter with 8 pins on IIRC a 0.1 spacing. Very easy to handle. If you are designing something for others to build (even in principle, i.e. you are making it an open design) then using impossible to handle parts is a bad thing if there are alternatives. The SAW filters I used are small enough that my 46-year-old eyes have trouble seeing them without a magnifying glass. :) I do almost all of my soldering under a stereo microscope any more. But I can solder down to 0201 discretes that way, although I don't like going smaller than 0402. I don't have a lot of experience with hot air soldering yet, but it has become quite available to hobbyists, with hot air systems now available for around $100. The Maker movement has done a lot of good in the area of making surface mount soldering more approachable by Joe Random Hobbyist. Now, one of the engineering problems I'd need to solve would be how FEW PCB layers I could get away with using that FPGA. 16+ layers is not uncommon for full die escape, but layer counts like that are far too expensive at the volumes this thing might sell in. Cell phones have high layer counts, but only because they sell in huge volumes. I favor Xilinx FPGAs since they're what I use in my day job, and those are all BGAs. I would not offer this device as a kit in any case; I've helped Ian out doing rework for US FreHD customers, and even good old through-hole soldering can be hard for folks without a lot of experience. I'd rather design for automated assembly than spend a lot of time on tech support for kit builders who had trouble. With a BGA on it, the board's going through a reflow oven anyway. And IIRC US NTSC uses AM sound (Europe uses FM). I think you can forget about stereo sound, since I doubt any home computer had a stereo RF modulator. No, I think it's FM. I recall listening to TV audio on my US FM tactical mil radios whose frequency coverage extended over the bottom 2-3 VHF TV channels, back before they turned off the analog broadcasts. I agree that stereo support isn't needed, as stereo TV post-dates the computers in question if I'm not mistaken. But if I do the final demod digitally in an FPGA, then adding AM support wouldn't be a big deal if needed. Be warned that there are many versions of PAL. That sounds like a deep rabbit hole to fall down! It might result in a case of if you want me to add support for the computers from your country, send me one so I can develop with it. But this is also a point in favor of using an FPGA: Fairly major architectural changes just look like firmware upgrades to the end user, who can remain blissfully ignorant of my development pain. :) If I use one of the Zynq chips (which I'm currently favoring), then upgrades can probably be as simple as swapping an
Re: 8-bit Computer TV Channel Use
On Sat, 23 May 2015, Chris Osborn wrote: The GBS-8200/8220 doesn’t support composite input, only RGB. I’ve used the board on quite a few of my computers that output RGB and it works fine. I’ve even got a couple of blog posts: ZX Spectrum 128:http://www.insentricity.com/a.cl/233 Commodore 128 CGA: http://www.insentricity.com/a.cl/219 BBC Micro: http://www.insentricity.com/a.cl/211 I still need to hook it up to the CoCo 3 RGB, but I can’t imagine any reason it wouldn’t work. It also works fine with my Apple IIgs. That really surprises me. Mine was utterly unusable with the IIGS. The desktop (and all icons, folders, etc.) had distinct vertical bands through them. Also, lots of dot-crawl at sharp edges from what I recall. I rather strongly suspect that there isn't any such thing as a single GBBS-8200. Rather, the manufacturer is constantly changing the firmware (if not hardware) and it's a crap shoot as to what particular ideosyncrasies will be encountered with an individual board. Has anyone heard talk of the GBBS boards being field flashable? --
Re: 8-bit Computer TV Channel Use
On May 22, 2015, at 9:26 AM, Mark J. Blair n...@nf6x.net wrote: I've ordered a $15 composite to HDMI converter from Amazon to try out for myself with my Apple IIe and IIc. I'd also like to try out my Color Computers with a modern monitor to see if the color aliasing used by some games can be reproduced. I don't have a modern television, but I might still have a crusty old VCR out in the junk pile whose tuner output could be fed into the $15 converter. I’m anxious to hear reports on it. I’ve tried a lot of different things and so far nothing can handle the NTSC color signal that the Apple II puts out. Same with the Atari 800. I just end up with a monochrome screen with lines instead of colors. -- Follow me on twitter: @FozzTexx Check out my blog: http://insentricity.com
Re: 8-bit Computer TV Channel Use
On Fri, 22 May 2015, Chris Osborn wrote: Heh, I have a few already. :-) I’ve even got one of those funny looking ones that has knobs on it. With VHF UHF dials. And fine tuning. And only screw terminals on the back, none of those fancy RCA/phono jack connectors on it. A little over half a century ago, UHF was an extra price option! My brother and I pooled our money and bought a 19 Philco portable. Our father chipped in the additional to get UHF. I remember watching the Cuban missile crisis on it, with my father muttering, The SOB has gotten us into war!
RE: 8-bit Computer TV Channel Use
Yes, video is tricky. I've just had an experience which emphasizes the topic under discussion. The main problems stem from the fact that these computers output anything but broadcast-standard video. In some cases it was because they were built to a price and it was 'what can we get away with'. In others it was more a case of getting extra features (like colour) almost for free. Just recently I got hold of an Amstrad CPC 464. http://www.classic-computers.org.nz/collection/amstradcpc464.htm Incidentally, one of the better things (for me) about Amstrad machines is that service manuals existed for them. Said manuals are essentially a schematic and a parts list, but that is all that is normally needed. Certainly for the older machines (all the CPCs and PCWs and the earlier PCs) they are not just boardswapper guides. It didn't come with its screen though (dedicated screens were sold with the machine). However British enthusiasts had developed an RGB to SCART cable What are you doing for the PSU (the computer ran off the SMPSU in the monitor IIRC)? for this very problem. Problem for me was that although SCART is a common video interface in Europe, it's rare in New Zealand. However I noted there One problem with SCART (and I don't think it's the cause of your problems) is that it is several interfaces on one connector. In particular there is composite video, RGB video (using the composite pin for sync) and later S-video (using the composite pin for Y and IIRC the 'red' pin for C). Not all devices implement all parts of the interface. In particular UK TVs almost always have the RGB inputs, VCRs did not. The CPC output is RGB video, and AFAIK the CPC-SCART cable is a simple cable with perhaps level-shifting resistors inside. So it will use the RGB pins on the SCART connector. -tony
Re: 8-bit Computer TV Channel Use
On May 22, 2015, at 1:31 PM, Chuck Guzis ccl...@sydex.com wrote: Do you have anything like Freecycle in your area? Usually, if you say you're looking for an old-style TV, people will jump at the chance to give away the old sets. Heh, I have a few already. :-) I’ve even got one of those funny looking ones that has knobs on it. With VHF UHF dials. And fine tuning. And only screw terminals on the back, none of those fancy RCA/phono jack connectors on it. I really need to do a cap kit on it though, it takes forever to warm up, and the tuning drifts while it’s on and I have to change the channel and then back to get it to lock on again. -- Follow me on twitter: @FozzTexx Check out my blog: http://insentricity.com
