Really cool project, I'm really thinking of buying it. But I think it would be much better if the output video connector is an HDMI with audio passthrough added (or DisplayPort if you want to avoid the fee)
Oetker wrote on 2023-02-09, 12:19:Just to be clear, though, if I understand the website correctly the hardware can't upscale to 1600x1200@70Hz, right? So when running at 70Hz the upscaling needs to be done by the monitor.
That is right. The board we use guarantees a maximum rated support for 118.8MHz video pixel clock, which provides 1440x1080@70Hz and 1600x1200@57.4Hz at CVT-RBv2 standard timings. Unfortunately the 1600x1200@70hz resolution is a bit beyond that, at 145.8MHz.
Our core is actually developed to be stable at timings even higher, up to 170MHz pixel clock speed, so we know that the board logic itself will work at that resolution and even higher - the tricky part is that the video serializer subsystem on the board is not rated by the manufacturer to go that high.
So this why we can only advertise the above resolutions, those are guaranteed to work by the spec.
At the same time, we observe that rated specifications can sometimes be a bit cautious. So we give enthusiasts the possibility to tinker by providing an overclocking option (which is maybe a slight misnomer, there is no overvolting or observed danger of breaking the board by using that option) to try driving the board at faster clock speeds.
ViTi95 wrote on 2023-02-09, 12:58:Really cool project, I'm really thinking of buying it. But I think it would be much better if the output video connector is an HDMI with audio passthrough added (or DisplayPort if you want to avoid the fee)
Thanks!
Regarding audio, many displays have a 3.5mm input jack, so that will amount to running a second cable from the sound card to the display. Adding audio processing was considered, but rejected actually due to space constraints - the video scalers take up the majority of the current board size, and we would have to go with a part that is of the next order of magnitude higher in the portfolio. Presumably most existing DOS PC setups already have dedicated speakers, so it was easier to exclude that from the design for now. That might be a future feature for later generation, if the project gets that far!
Way to hack the feature connector!
What FPGA is used and will the RTL be available (perhaps under a separate license?)
Not that I have any time to hack on this myself, but it seems like something that could use a wide net of developers based on variations of the feature connector implementations.
tfinn - VLA / DC5 / K
poofygoof wrote on 2023-02-10, 05:54:What FPGA is used and will the RTL be available (perhaps under a separate license?)
Not that I have any time to hack on this myself, but it seems like something that could use a wide net of developers based on variations of the feature connector implementations.
The exact FPGA is not just yet locked down. That is the current work item that we are chasing to lock down so we can proceed to finalize the board design.
The goal we are targeting now is to develop a fully tested product to the market. Future gen 2 development or other licensing options will be a thing to ponder for later, once we prove to ourselves we can reach this first milestone.
poofygoof wrote on 2023-02-10, 05:54:Way to hack the feature connector!
😎
clb wrote on 2023-02-07, 09:36:While we are visiting this topic, there is also a third demo, Kukoo 2, which was consciously rejected from being supported. It does palette color changes at each scanline to get more than 256 colors in a single frame. Supporting that demo would require actively delaying the video signal in order to sync up palette writes and the Feature Connector video signal with each other at hsync. Supporting this demo would add more processing delays to CRTT, which many people would not prefer, so we chose to be practical and optimize to keep the processing latency down. The Kukoo2 demo will show on CRTT, but the palette will be off.
Note that there are some games that also change palette entries mid-frame, Lemmings being a notable example.
That is true. Both Lemmings level intro and Pinball Fantasies table select screens have operation where they change palettes in the middle of a frame. Both of those are included in our test harness and do work properly.
Hi,
The CRT Terminator Digital VGA Feature Card ISA DV1000 is a really great project.
Thank you very, very, very, much for realizing this awesome idea.
Many years ago I also was interested in the feature connectors of VGA cards and its in-deep details (pinouts, diagrams, signals, timings etc.).
I also was interested in converting them to DVI anyhow.
So, I did write an email to frame grabber companies, like:
startech.com , Stemmer imaging, unigraf.fi , The imaging source , datapath.co.uk ,
euresys.com(picolo HD3G) , epiphan (true RGB [not YUV 4:2:2] DVI and true RGB HDMI Frame Grabbers)
...and asked them if they could realize a capture device / frame grabber device with support for:
Video Feature Connector and/or Vesa Advanced Feature Connector.
But finally nothing was developed/realized.
Your news changes everything!!!
And with your CRT Terminator it will be possible (hopefully soon 😉 ) to grab pixel perfect snapshots and video captures from any x86 computer with a feature connector enabled CGA/EGA/(S)VGA card.
(I know there are already similar possibilities for the:
screen_capture_method_before_the_operatings_system_starts--job, like: PCem, x86box, DosBox, VMware, Bochs and VirtualPC.
But these are just for a small number of certain emulated/virtualized x86 systems.)
It could be that the CRT Terminator will also be famous like other xxx-to-HDMI projects:
gcvideo - GameCube Digital AV converter (to HDMI)
https://github.com/ikorb/gcvideo
clb wrote on 2023-02-06, 08:12:If someone can dig up any official web archive sources to confirm or deny, that would be interesting.
Well, reagarding clarify all the different technical terms...:
1) ...it seems to be that many constellations / compilations / compositions are possible:
"IBM VGA feature connector", "VGA feature connector",
"IBM video feature connector", "video feature connector",
"IBM feature connector"
"8-bit feature connector", "8bit feature connector"
(http://notes-application.abcelectronique.com/004/4-7933.pdf , https://www.vision-systems.com/cameras-access … /frame-grabbers)
"VESA feature connector", "VESA video feature connector", "VESA standard Feature Connector"
"IBM-type feature connector", "EGA feature connection", "EGA feature connector"
"LBP extension" -- "Vesa connector", "LBP VESA feature connector", "VESA compliant VGA feature connector"
(....and the "new": "VESA Advanced Feature Connector")
You can simply use one of the "xxx feature connector" keyword +plus+ pdf (or: doc / ps / txt / rtf / wpf))in google (e.g.: "IBM video feature connector" pdf)
to find many different and old/classic (graphics card related) documents and user/service manuals regarding the feature connector.
It seems to be that the original IBM feature connector is/was realized as an edge connector.
And it seems to be that the "mixture" of
a) a kind of a VESA standardization("Y..." and "Z...") (I do not mean VAFC) and
b) the IBM standardized feature connector
...was realized as a pin header
Here is an example of the "mixture" of both standards (IBM/VESA) or a "mixture" of both company names (IBM/VESA) in one document regarding the feature connector:
MiniModule/SVG-II Technical Manual
https://www.lanl.gov/orgs/n/n1/FMTTD/elec_cab/comp_block/ampro/video_controller/mmsvg_tech_man.pdf
-->
"The MiniModule/SVG-II provides a feature connector which presents all the standard IBM signals in the VESA standard pinout"
"The signals are in the same order as a standard VESA feature connector found on some desktop PC expansion card"
J3 Pin____Standard Connector Pin____Signal Description
2____Y1____Data Bit 0
4____Y2____Data Bit 1
6____Y3____Data Bit 2
8____Y4____Data Bit 3
10____Y5____Data Bit 4
12____Y6____Data Bit 5
14____Y7____Data Bit 6
16____Y8____Data Bit 7
18____Y9____DAC Clock
20____Y10____Blank
22____Y11____H Sync
24____Y12____V Sync
26____Y13____Ground
1____Z1____Ground
3____Z2____Ground
5____Z3____Ground
7____Z4____EVIDEO
9____Z5____ESYNC
11____Z6____EDCLK
13____Z7____n/c
15____Z8____Ground
17____Z9____Ground
19____Z10____Ground
21____Z11____Ground
23____Z12____n/c
25____Z13____n/c (key)
Here is an example for: "VESA standard Feature Connector"
https://dosdays.co.uk/media/orchid/kel64&ez.pdf
"VESA Feature Connector Pin-outs"
"The VESA standard Feature Connector (or Auxiliary Video Connector as it is sometimes called) is located at the top of the Kelvin[...]"
Pin____Function____Pin____Function____Pin____Function____Pin____Function
Y1____Pixel Data 0____Y8____Pixel Data 7____Z2____Ground____Z9____Ground
Y2____Pixel Data 1____Y9____Pixel Clock____Z3____Ground____Z10____Ground
Y3____Pixel Data 2____Y10____Blanking Z4 (See Note 1)____Z11____Ground
Y4____Pixel Data 3____Y11____Hor. Sync Z5 (See Note 2)____Z12____No Connect
Y5____Pixel Data 4____Y12____Vert. Sync Z6 (See Note 3)____Z13____No Pin (Key)
Y6____Pixel Data 5____Y13____Ground____Z7____No Connect
Y7____Pixel Data 6____Z1____Ground____Z8____Ground
An interesting point are the: "NOTES:"
(1) Low Enable External Pixel Data Input to the motherboard DAC.
(2) Low Enable External Sync and Blanking Inputs to the motherboard DAC.
(3) Low Enable External Pixel Clock Input to the motherboard DAC.
Here is an example for: "IBM-type feature connector":
https://minuszerodegrees.net/manuals/NSI%20Lo … vertisement.pdf
Here is an example of timings and a timing diagram / timing parameters of a VESA FEATURE CONNECTOR PORT :
https://0x04.net/~mwk/stg-17xx.pdf
Here are some further information which could be helpfully maybe to understand the IBM standard and the IBM/VESA mixtured standard:
https://www.datasheetarchive.com/pdf/download … e%2520connector
https://datasheet.datasheetarchive.com/origin … DSAE0072905.pdf
TE430VX
Motherboard
Technical Product Specification
Order Number 281817-003
May 1996
-->
"The motherboard supports the 26-pin VESA feature connector for synchronizing graphics output with an external NTSC or PAL signal and a shared frame buffer interface to maximize multi-media performance."
"Boards configured with the Trio64 V+ will have a 34 pin feature connector that supports the VESA requirements as well as the LPB (Local Peripheral Bus) that provides a glueless bi-directional interface to a video companion device such as an MPEG/live video decoder."
https://www.datasheetarchive.com/pdf/download … e%2520connector
https://datasheet.datasheetarchive.com/origin … DSAE0072903.pdf
RU430HX
Motherboard
Technical Product Specification
Order Number 281810-002
May 1996
Here is another kind of a video related feature connector (an external one) - maybe also VESA standardized anyhow?
https://www.artisantg.com/info/ziatech_zt_6631_manual.pdf
-->
"The Feature connector. 26-pin (dual 13-pin), female right angle connector with 0.050" lead spacing."
Here...:
"http://web.archive.org/web/20001214171500/http://www.hut.fi/Misc/Electronics/docs/pc/vga_feature.html"
"http://web.archive.org/web/20010417153715/http://www.epanorama.net/documents/pc/vga_feature.html"
https://www.epanorama.net/documents/pc/vga_feature.html
"http://web.archive.org/web/20001215005800/http://www.hut.fi/Misc/Electronics/docs/pc/vgainfo.html"
"http://web.archive.org/web/20010423130604/http://www.epanorama.net/documents/pc/vgainfo.html"
http://www.epanorama.net/documents/pc/vgainfo.html
...you can read about the (default original IBM video) feature connector in context with VESA:
"VGA feature connector is a 8-bit expansion bus for VGA card standardized by VESA."
Further links:
https://www.epanorama.net/documents/pc/
https://www.epanorama.net/documents/pc/vga_fe … e_problems.html
https://www.epanorama.net/documents/pc/vafc.html
2) ...there are some web archive sources:
https://web.archive.org/web/*/vesa.org/* --> use filter: VAFC
-->
http://www.vesa.org/dload/summary/sum_vafc_sw.pdf.html
http://www.vesa.org/dload/summary/sumvafc_hw.htm
http://www.vesa.org/dload/summary/sumvafc_sw.htm
http://www.vesa.org/public/VAFC/
http://www.vesa.org/Public/VAFC/VAFCv1r11hw.pdf
http://www.vesa.org/Public/VAFC/VAFCv1sw.pdf
http://www.vesa.org/summary/sumvafc_hw.htm
http://www.vesa.org/summary/sumvafc_sw.htm
(further standards are here: https://archive.org/download/VESAPublicStandards)
It would be great if some original IBM links (.pdf / .doc / .txt / .ps / .wpf / .rtf) regarding the feature connector could be found at web.archive.org
I was not succussful in finding original IBM documents regarding the VGA / video feature connector in the web.archive.org - until now.
(I will try a new search in the next days).
Well, here are some further (maybe) interesting links and youtube videos referring the Video / VGA / VESA feature connector:
Google: "feature connector"
Google: (video)"feature connector" "Evaluation Board"(s)
Google: "VGA feature connector compatible"
Google: "feature connector" "ttl"
Google: "feature connector" "tmds"
Google: "feature connector" "lvds"
https://www.google.com/search?q="What+is+the+feature+connector+on+my+video+card+for"
-->
comp.sys.ibm.pc.hardware.video FAQ, Part 4/4 -- http://www.faqs.org/faqs/pc-hardware-faq/video/part4/
https://www.ineltro.ch/media/downloads/SAAIte … 20f7b444406.pdf
(another kind of a feature connector in context with "SDVO": "SDVO feature connector" , "SDVO to DVI")
http://www.faqs.org/faqs/pc-hardware-faq/video/part1/
https://forum.vcfed.org/index.php?threads/vga … onnector.42898/
-->
"https://books.google.de/books?id=vcqI6sY2e-kC&pg=PA298&lpg=PA298&dq=ega+feature+connection&source=bl&ots=5ZcdzQAqEh&sig=DzN59h98XDAH5xaqXRIKieMWojg&hl=en&sa=X&redir_esc=y#v=onepage&q=ega%20feature%20connection&f=false"
"http://www.afiata.com/circuit-diagram-laptop-lcd-display-to-vga-interface-project/#.Uqw6ysQW3us"
--> "TTL level clock and 8 data lines interface that has signals that match with 26 pin “VGA feature connector”"
http://www.interfacebus.com/Design_Connector_Monitor_Buses.html:
"VAFC; VESA Advanced Feature Connector. A point-to-point interface between a display adaptor and video board. 32-bits at 150MBps over an 80-pin cable.
VFC; VGA Feature Connector. A point-to-point interface between two video boards. 8-bits at 40MBps over an 26-pin cable via a card edge connector."
Youtube: vga feature connector
https://www.youtube.com/results?search_query=vga+feature+connector:
Maybe, all the information above could help you anyhow for the great CRT terminator project.
Now, here are some questions / feature requests:
Could you develop/improve the CRT Terminator in a way that it supports all kind of feature connectors ?
...maybe via auto detection feature or with the help of a DIP switch / with the help of onboard jumpers, like: "Auto","VFC", "VAFC", "AMC" , "VMC"(VMChannel / Vesa Media Channel).
Could you publish any kind of a feature connector table / matrix where you can see:
the standard (its name, its known name variations/constellations), the speed, the signal type (TTL, LVDS, TDMS, etc...), voltage levels, timings, and further properties?
Thank you very much.
Borg Number One wrote on 2023-02-20, 22:38:Hi,
The CRT Terminator Digital VGA Feature Card ISA DV1000 is a really great project.
Thank you very, very, very, much for realizing this awesome idea.
Thanks! We have since heard from several people that they have thought about this kind of project. It certainly feels like the VGA cards are begging for this to become a thing!
Borg Number One wrote on 2023-02-20, 22:38:And with your CRT Terminator it will be possible (hopefully soon 😉 ) to grab pixel perfect snapshots and video captures from any x86 computer with a feature connector enabled CGA/EGA/(S)VGA card.
I still haven't been able to find that perfect video capture USB box or PCI-E card that would allow doing pixel perfect captures, and not cost 500 euros. That hardware space looks pretty tricky as well. Like mentioned before, 4:2:0 is possible with StarTech USB3HDCAP.
However with CRT Terminator one can capture e.g. 320x200 modes using the passthrough mode, which will get doubled up to 640x400, so the 4:2:0 is not observable there. When recording to OBS, one can then scale the data back up to e.g. 1600x1200 or similar.
Borg Number One wrote on 2023-02-20, 22:38:1) ...it seems to be that many constellations / compilations / compositions are possible: […]
1) ...it seems to be that many constellations / compilations / compositions are possible:
It seems to be that the original IBM feature connector is/was realized as an edge connector.
And it seems to be that the "mixture" of
a) a kind of a VESA standardization("Y..." and "Z...") (I do not mean VAFC) and
b) the IBM standardized feature connector
...was realized as a pin header
I agree now with this characterisation, it does seem that VESA did pick up the connector in their standards, and IBM/VGA Feature Connector wording was used to refer to the edge connector, and VESA Feature Connector was used to refer to a pin header connector.
Borg Number One wrote on 2023-02-20, 22:38:Here is another kind of a video related feature connector (an external one) - maybe also VESA standardized anyhow? https://www.a […]
Here is another kind of a video related feature connector (an external one) - maybe also VESA standardized anyhow?
https://www.artisantg.com/info/ziatech_zt_6631_manual.pdf
-->
"The Feature connector. 26-pin (dual 13-pin), female right angle connector with 0.050" lead spacing."
This is an interesting PDF, since for the first time, I find an explicit mention from a manufacturer about max rated pixel clock support via the Feature Connector for signal integrity:
"The Feature connector signals come directly from the VGA controller and consist of the same signals that are fed to the RAMDAC for producing the analog display. This data is fed at the pixel clock rate of the VGA controller. Depending on the graphics mode used, this can range from 12 to 28 MHz for standard VGA modes and up to 108 MHz for higher resolution SVGA modes. The Feature connector's useable upper limit is approximately 40 MHz, which corresponds to a maximum resolution of 800 x 600.
Because the Feature data can be at such a high clock rate, you must be careful when cabling to the connector. As with any high speed data cable, pay careful attention to noise reduction. Standard 28 gauge unshielded flat cable will work fine for short distances but at longer lengths noise will begin to degrade the system and cause pixel streaking. Shielded cable can be used for applications that require longer distances."
Thanks also for digging up all the other links. We've been visiting many of the same sites.
This article is however something worth highlighting about VAFC: https://web.archive.org/web/20050515200139/ht … VAFCv1r11hw.pdf
That is the authoritative reference on that standard.
Borg Number One wrote on 2023-02-20, 22:38:Could you develop/improve the CRT Terminator in a way that it supports all kind of feature connectors ? ...maybe via auto detect […]
Could you develop/improve the CRT Terminator in a way that it supports all kind of feature connectors ?
...maybe via auto detection feature or with the help of a DIP switch / with the help of onboard jumpers, like: "Auto","VFC", "VAFC", "AMC" , "VMC"(VMChannel / Vesa Media Channel).Could you publish any kind of a feature connector table / matrix where you can see:
the standard (its name, its known name variations/constellations), the speed, the signal type (TTL, LVDS, TDMS, etc...), voltage levels, timings, and further properties?
There actually aren't that many that would be interesting. I posted my knowledge so far into this thread: Does anyone know of other than S3 manufactured PCI video cards with "16-bit VESA LPB" connector?
The Ati Multimedia Channel (AMC) and VESA 8-bit Local Peripheral Bus are for controlling MPEG player cards (e.g. play, stop, seek, status), and AMC passes MPEG audio through. So they don't carry any pixel data itself, so there is no benefit from them for this project.
The first of the two buses that do contain video data is the 16-bit Vesa LPB bus, which expands the VGA Feature Connector from 8 bits over to 16-bit wide data. It looks like only S3 ever implemented this bus on their cards, I have not found other manufacturers to do so.
The second one is the VAFC bus, which expanded the pixel data bus to 32-bit width. However I think even fewer manufacturers implemented that one. It is really hard to come up with any boards to buy on eBay, for example.
With CRT Terminator we are now focusing on the 8-bit Feature Connector. What future will bring, will then be a chapter two after that.
If I remember well, the Compaq QVision 1280 and the Compaq QVision 2000 had the VESA Advanced Feature Connector. Very strange port, similar to a SCSI 50-pin connector.
Looking at those cards, they indeed do seem to have a VAFC connector. The Compaq QVision 2000 card ( https://wiki.preterhuman.net/Compaq_QVision_2000 ) has a MGA chip on it, so looks like it is a rebranded Matrox Impression card: http://retronn.de/imports/hwgal/hw_matrox_imp … ssion_lite.html .
This video card connector used for? finds a picture of a S3 ISA VLB card and then a Truevision Targa manufactured card with VAFC as well. And a Olivetti motherboard with a Trident manufactured graphics chip on it. That one is interesting, haven't seen a standalone Trident card with VAFC in it.
Very exciting project IMO. The CRTs will all be dead one day, and these are the projects we'll need. Thanks to RGBtoHDMI, I already know my CGA & EGA needs are future-proofed. The VGA situation is a lot muddier, and it's great to see a solution like this being developed.
Since it works with ISA video cards, will it also work with VLB cards? Or do you run into similar issues to PCI?
World's foremost 486 enjoyer.
Pierre32 wrote on 2023-03-04, 08:20:Very exciting project IMO. The CRTs will all be dead one day, and these are the projects we'll need. Thanks to RGBtoHDMI, I already know my CGA & EGA needs are future-proofed. The VGA situation is a lot muddier, and it's great to see a solution like this being developed.
Thanks, yeah, many people do find uses for CRTs, people will take care of them for a long time, but those are not for every use case and not to every retro hobbyist. E.g. for YouTube video recording and Twitch streaming, I doubt that many people prefer to get analog VGA->digital conversion artifacts in those.
It has been about two months since the announcement, time does fly by fast. A short and quick status update is that the first release candidate PCB is nearing completion. Paralleling that, I have been expanding our test database of different ISA VGA cards to validate compatible behavior. There will be some jumper switches on board to configure to adapt to quirks, ATI 28800 family, Tseng ET4000, Trident TVGA8816 and Paradise PVGA1 are so far on the naughty list, fortunately they still work well with configuration.
There are a few interesting observations with this test database:
- some VGA cards have an absolutely unusably smooth/blurry VGA output that make them undesirable.. but Feature Connector is not affected since it bypasses the RAMDAC, so with CRT Terminator these VGA cards produce as pixel precise image as any other card will, sweet!
- some VGA cards (Oak OTI037C and ATI 28800-5 so far) do not implement correct clock 1:2 halving for Feature Connector, resulting in e.g. mode 13h having twice the pixel clock that it should have. This is mostly not a problem, but cascades to be an issue for anyone who wants that absolute pixel perfect scaling, and also provides some challenges in games with nonstandard video modes.
- the clock oscillators on many old cards are quite jittery, so some cards are not able to output a stable 800x600 signal through feature connector due to this. It will be an interesting mod to try to replace a poor oscillator on a card with a more precise modern alternative, to see if the clock noise could be successfully remedied. Cirrus Logic cards (CL-GD5422, CL-GD5429 "Eval board") so far have had the best/most stable Feature Connector quality I have seen.
Work is continuing, the main focus we have is currently on the DVI-D output side, and I have started to accumulate a number of different flat displays in corners of my lab. We have been in contact with ASUS and StarTech to figure out details about how their displays/capture cards expect to synchronize to digital video in the hopes of being able to produce the most compatible video signal.
If the board RC does well in tests, it will be all systems go for the first (small) production batch, and once we have an ETA of when the parts would arrive, we'll be able to actually start taking orders in (we will only take actual orders when we can provide a shipping date estimate). I would estimate this still to be something near the end of the year right now.
keenmaster486 wrote on 2023-03-30, 00:30:Since it works with ISA video cards, will it also work with VLB cards? Or do you run into similar issues to PCI?
This an interesting point that was the focus of a recent investigation. When I wrote the first announcement page website https://oummg.com/ , I had optimistically marked VLB ISA cards to be compatible, but had not yet had a chance to test. Now I have, and unfortunately it does look like this will be something that will need to be crossed out from the initial support list 🙁
To be more precise with ISA, ISA VLB and PCI: the way that CRT Terminator works with palettized 256-color VGA video modes is that it snoops the ISA bus to find writes to the palette IO ports. This is like how MPEG add-on cards would also work.
The ISA bus however is distinct from the PCI bus, and also it looks like it is distinct from the VLB bus. The result is that if the VGA card is located on the PCI or VLB bus, palette IO writes will not be broadcast to the slow ISA bus at all, hence the VGA palette will be all wrong.
That is, CRT Terminator does work also with ISA VLB and PCI cards to output a video image, but it won't be able to show it with the correct palette.
Now, there is that option "VGA Palette Snoop" on some motherboard BIOSes that provides an interesting question, whether enabling that would be the remedy this issue. The option *was* created specifically for this purpose to enable MPEG capture cards to see the palette. However, there are important details here that I don't currently know the answer for:
1. will the VGA Palette Snoop option always allow writes to the snooped specifically from the ISA bus; or is the VGA Palette Snoop option there to enable other PCI cards to snoop palette writes from a VGA adapter also on the PCI bus? That is, does the option enable snooping to take place from the ISA bus, or from PCI bus, or from both? (or might this behavior even be motherboard dependent?)
2. are there any ISA VLB motherboards that would have the VGA Palette Snoop BIOS option, that would enable ISA cards to observe VGA palette writes to an ISA VLB video card?
So far, I unfortunately do not have any motherboards that would have the VGA Palette Snoop option to test out. But I have tested that CRT Terminator will not produce the correct palette when used with a PCI or ISA VLB video card, at least on the sample size of one motherboard that I have tested.
Cautiously, one might imagine that it could work with a PCI or ISA VLB video card, if the motherboard has that VGA Palette Snoop option to enable, but this will require further testing.
clb wrote on 2023-04-02, 08:13:2. are there any ISA VLB motherboards that would have the VGA Palette Snoop BIOS option, that would enable ISA cards to observe VGA palette writes to an ISA VLB video card?
at least some cards had workaround build in https://www.vgamuseum.info/index.php/cpu/item … logic-cl-gd5424 Technical Reference Manual :
"Shadow DAC Writes on Local Bus: If this bit is programmed to ‘0’, writes to
the internal DAC return LBA# and RDY# normally. If this bit is programmed to
‘1’, writes to the DAC addresses accept data, but do not return LBA# or RDY#,
causing the write to be passed on to an external DAC on the ISA bus. The
reset state of this bit is ‘1’. Reads to the DAC addresses always operate normally"
I'm trying to work out if I can pass video from the Sigma Designs X-Card PCI DVD/DIVX board through the VESA feature connector on video cards, and it seems like there was some change to the standard in 1997. I can't find any pdf of this standard online though.
"November 1997 VESA Video Interface Port (VIP) ™ Standard, Version 1.1: This standard that defines the method for connecting digital video devices to graphics display adapters. VESA VIP is a dedicated physical connection between a graphics adapter and one or more 3rd party hardware devices, such as MPEG-2 decoders, video digitizers, etc. With a dedicated connection, devices supplying video data do not have to compete with other data movement on the current industry standard PCI bus."
The VESA VIP connector is the same 26 pin connector as the VESA feature connector - but cards predating this clearly couldn't be compliant with the 1997 standard. Capture cards like the PDI Sweetspot and Holo3dgraph allowed pass through of the X-Card via the 26 pin connector, but it wouldn't make much sense to pass through DVD video if it were limited to 256 colours?
clb wrote on 2023-04-02, 08:13:So far, I unfortunately do not have any motherboards that would have the VGA Palette Snoop option to test out. But I have tested that CRT Terminator will not produce the correct palette when used with a PCI or ISA VLB video card, at least on the sample size of one motherboard that I have tested.
Cautiously, one might imagine that it could work with a PCI or ISA VLB video card, if the motherboard has that VGA Palette Snoop option to enable, but this will require further testing.
My main Socket 7 machine has the VGA Palette Snoop option. I'd be happy to pay for shipping to help test prototypes if that's something you're interested in.
World's foremost 486 enjoyer.
Any updates on this?
World's foremost 486 enjoyer.
Hey! Sorry for the delayed reply, I missed an email ping about your question, until had a friend tell me that there was an unanswered comment posted.
Indeed there are updates. Summer in Finland means summer vacations, and that means that we have had time from our day jobs to focus on the project on a higher gear. I have been fixing various issues on the video and memory subsystem. The Kukoo 2 demo I mentioned previously to not work, now works beautifully \o/ and a particularly malformed video signal generated by a game "Jump & Bump" also works now.
I have also been recording a video to introduce the card in action, and that will be out very soon. It won't be any super YouTuber quality and makes me slightly cringe hearing my own voice 😀 , but at least I hope will be informative to get a good first touch on how it will work in practice.
Functionally the card is in a great shape, and we got enough interest from our web site comments box that we have dared the risk to make an order for parts for the first production batch run. The PCB design is still going through one more iteration though, which hopefully will be the final. (like we hoped that the previous design would be, and the one before that.. you get the idea)
With respect to the PCI bus, we have been able to confirm that hybrid ISA+PCI motherboards that have the "VGA Palette Snoop" option available in the BIOS, will be able to support CRT Terminator, and the 8-bit video mode palette comes through correctly. Although there are some surprises with PCI as well:
- unlike with ISA VGA cards which all have had the Feature Connector enabled at boot that we have seen, e.g. the S3 Trio 64 PCI card needs the use of a separate config program (which S3 shipped) to enable the Feature Connector bus, so it will need an autoexec.bat launcher to enable video. This means it won't get video right from the boot (or from BIOS), maybe people will want to stay away from that card. Although curiously, I have a second copy of a S3 Trio 64 PCI which did not need this config program but it has an always-on FC bus, so go figure..
- e.g. Voodoo 3 PCI card offers Feature Connector apparently as a video input only, and not as video output, so is not compatible with CRT Terminator.
However all that said, PCI and ISA VLB will still be beyond the immediate scope, but the above means that interested people will be able to experiment.
Right now I am battling some issues with the web host to prove I will not be a spam emailer, to be able to send email updates to people who registered for updates (so I can actually send them the info I wrote in above), and working on writing documentation and a DOS config program for the card.
As for the "when can we get it" schedule, we are still a little bit time away, since the lead time for our order is stated to be about four months. 😒 We are still shooting that the first production boards will be able to go out before the end of the year.
I'll ping back here when the video goes live, so you can glimpse the first live debut of the card in action. 😀
