On a PC it is different, because you need to render the polygons in software. On an Amiga you basically draw lines into each bitplane, and then do a single area fill at the end, all with the blitter. The area fill won't…
That is an interesting difference with the 8088+CGA platform by the way. The Amiga has no problem displaying entire screens of uncompressed data. CGA however is so bandwidth-limited that you simply can't update an…
Well, I would argue that a 'conventional' video codec would not work nearly as well on a stock Amiga 500 as this polygon approach does. The closest thing to full-motion video on the platform was probably what they used…
The Amiga had a hardware blitter that was very good at drawing lines and doing area fills, so it made perfect sense to encode video to polygons on that particular hardware.
It was actually patented by Access Software, under the name of RealSound. https://en.wikipedia.org/wiki/RealSound
Having said that, the CGA card does not actually have its own clock. It takes the NTSC base frequency of 14.31818 MHz from the OSC-pin of the ISA bus. On early PCs, such as the IBM 5150/5160, the CPU frequency is also…
Yes, thanks! Fixed the original text.
Yes, combined with streaming the data from disk in realtime, and playing the audio over the PC speaker in this case, bit-banged. Given the limited performance of both the HDD system and the CGA adapter, the most…
The video clock (I assume you mean pixel clock) isn't relevant. The synchronization of video and audio happens on a per-frame basis. And since the frames are clocked out on the audio-clock, there cannot be any drift.
Yes, I posted a followup which investigates the issue somewhat further. It appears to be some bug with the message queue handling, specifically when the UI is in Aero mode. In classic mode, the problem is not there. In…
"Justify why people died" Lol, you sound as unhinged and radicalized as Jim. The point I was making was that all these people had a criminal record that showed they had a violent nature, and were likely there to cause…
The ATi Small Wonder is not entirely cycle-accurate. When I studied the CGADEMO by Codeblasters, I found that the scroller didn't look entirely correct, because the Small Wonder was slightly slower:…
I wonder... certain software, such as Flight Simulator and Lotus 1-2-3 had a profound effect on the level of compatibility of clones. So perhaps if software was released that demanded EVEN MORE compatibility, we would…
What may also have had an impact was that clones were generally XT-clones (using the newer, smaller ISA card layout, and no cassette port), not PC-clones. And indeed, they were specifically advertised as 'XT-clone',…
Yes, especially somewhat later in the life of the 8088, most applications would demand quite a bit of memory, and the 640k configuration became standard for the later 5160s and most clones. So I wouldn't be surprised if…
I wouldn't know if 'most of them' don't work, but I know for a fact that I have one (made by Vivanco, using a Prolific chip) that works fine in combination with my IBM 5160. I use it in combination with FastLynx, which…
In short, textmode gives you 80x25 characters of 8x8 pixel resolution each, making 640x200 resolution, with 16-colours, where each character can be assigned a foreground and background colour. The 'Macrocom Method'…
Correct, as "XT" stands for eXtended Technology. You can't extend it without having the basic technology first. The 5150, aka the PC, was that basic technology. However, in terms of CPU, graphics, sound and all other…
That was how the predecessor 8088 MPH worked. Area 5150 however is aimed at a TTL RGBI monitor, and as such, does not use NTSC composite artifacting. It can only display 16 colours at once. So in this demo, you get…
Yes, originally CGA and MDA at the same time. Hercules was a non-IBM standard, based on MDA. Hercules has 64k of memory, where 32k is in the area of MDA, and the second 32k overlaps with the CGA area. You could disable…
This was in the context of using the video as a texture. As I tried to explain, the RGB texture formats with 8-bit precision use 32-bit words. There are no 24-bit formats available as a texture format. NV12 is also a…
I would like to nuance that by saying it's nice if you have a good deal of domain knowledge, but my article focuses more on the case where you venture into new territory, and the architect is the person who needs to…
In theory emulators recreate the hardware in software. In practice, emulators approximate the hardware in software. In the case of PCs, there is so much hardware variation, that it was never a requirement to be very…
The artifact colours are quite off as well, so I suspect the card used was not a real IBM CGA card. On my ATi Small Wonder and Paradise PVC4 cards, I get the exact same Kefrens bars, with the top chopped off. Having…
Actually, IBM did not supply a TTL-monitor for CGA until 1983 (the 5153). So in the early days, using the composite output (which is standard on IBM CGA cards) would be the easiest way to get CGA output to a screen in…
On a PC it is different, because you need to render the polygons in software. On an Amiga you basically draw lines into each bitplane, and then do a single area fill at the end, all with the blitter. The area fill won't…
That is an interesting difference with the 8088+CGA platform by the way. The Amiga has no problem displaying entire screens of uncompressed data. CGA however is so bandwidth-limited that you simply can't update an…
Well, I would argue that a 'conventional' video codec would not work nearly as well on a stock Amiga 500 as this polygon approach does. The closest thing to full-motion video on the platform was probably what they used…
The Amiga had a hardware blitter that was very good at drawing lines and doing area fills, so it made perfect sense to encode video to polygons on that particular hardware.
It was actually patented by Access Software, under the name of RealSound. https://en.wikipedia.org/wiki/RealSound
Having said that, the CGA card does not actually have its own clock. It takes the NTSC base frequency of 14.31818 MHz from the OSC-pin of the ISA bus. On early PCs, such as the IBM 5150/5160, the CPU frequency is also…
Yes, thanks! Fixed the original text.
Yes, combined with streaming the data from disk in realtime, and playing the audio over the PC speaker in this case, bit-banged. Given the limited performance of both the HDD system and the CGA adapter, the most…
The video clock (I assume you mean pixel clock) isn't relevant. The synchronization of video and audio happens on a per-frame basis. And since the frames are clocked out on the audio-clock, there cannot be any drift.
Yes, I posted a followup which investigates the issue somewhat further. It appears to be some bug with the message queue handling, specifically when the UI is in Aero mode. In classic mode, the problem is not there. In…
"Justify why people died" Lol, you sound as unhinged and radicalized as Jim. The point I was making was that all these people had a criminal record that showed they had a violent nature, and were likely there to cause…
The ATi Small Wonder is not entirely cycle-accurate. When I studied the CGADEMO by Codeblasters, I found that the scroller didn't look entirely correct, because the Small Wonder was slightly slower:…
I wonder... certain software, such as Flight Simulator and Lotus 1-2-3 had a profound effect on the level of compatibility of clones. So perhaps if software was released that demanded EVEN MORE compatibility, we would…
What may also have had an impact was that clones were generally XT-clones (using the newer, smaller ISA card layout, and no cassette port), not PC-clones. And indeed, they were specifically advertised as 'XT-clone',…
Yes, especially somewhat later in the life of the 8088, most applications would demand quite a bit of memory, and the 640k configuration became standard for the later 5160s and most clones. So I wouldn't be surprised if…
I wouldn't know if 'most of them' don't work, but I know for a fact that I have one (made by Vivanco, using a Prolific chip) that works fine in combination with my IBM 5160. I use it in combination with FastLynx, which…
In short, textmode gives you 80x25 characters of 8x8 pixel resolution each, making 640x200 resolution, with 16-colours, where each character can be assigned a foreground and background colour. The 'Macrocom Method'…
Correct, as "XT" stands for eXtended Technology. You can't extend it without having the basic technology first. The 5150, aka the PC, was that basic technology. However, in terms of CPU, graphics, sound and all other…
That was how the predecessor 8088 MPH worked. Area 5150 however is aimed at a TTL RGBI monitor, and as such, does not use NTSC composite artifacting. It can only display 16 colours at once. So in this demo, you get…
Yes, originally CGA and MDA at the same time. Hercules was a non-IBM standard, based on MDA. Hercules has 64k of memory, where 32k is in the area of MDA, and the second 32k overlaps with the CGA area. You could disable…
This was in the context of using the video as a texture. As I tried to explain, the RGB texture formats with 8-bit precision use 32-bit words. There are no 24-bit formats available as a texture format. NV12 is also a…
I would like to nuance that by saying it's nice if you have a good deal of domain knowledge, but my article focuses more on the case where you venture into new territory, and the architect is the person who needs to…
In theory emulators recreate the hardware in software. In practice, emulators approximate the hardware in software. In the case of PCs, there is so much hardware variation, that it was never a requirement to be very…
The artifact colours are quite off as well, so I suspect the card used was not a real IBM CGA card. On my ATi Small Wonder and Paradise PVC4 cards, I get the exact same Kefrens bars, with the top chopped off. Having…
Actually, IBM did not supply a TTL-monitor for CGA until 1983 (the 5153). So in the early days, using the composite output (which is standard on IBM CGA cards) would be the easiest way to get CGA output to a screen in…