An IBM XT with 4.77MHz can display color video | Hacker News Reader

An IBM XT with 4.77MHz can display color video

oldskool.org

93 pointssgt40 comments

Those demoscene guys are probably some of the most impressive programmers I've ever seen. It's amazing the kind of visual displays they can produce with just 4kb or 64kb of code.

Yes but this has nothing to do with the video at hand. Most of the time the 4kb and 64kb demos are using procedural algorithms to fit in small amounts of memory, and with modern PCs it's kind of cheating because they use system libraries which are much bigger than 64kb in the first place.

Here, what's impressive is the ability to render video full speed on something AS SLOW as the first 8088. Pretty cool.

I think the OP was talking about the real demo scene like on the c64 or Amiga rather than on the PC.

Which were working in the same as the parent describes for the PC.

I'm pretty sure DirectX and OpenGL provide significantly more function calls and capabilities than 8-bit machines did.

> I'm pretty sure DirectX and OpenGL provide significantly more function calls

You bet! Small demos on PC are seriously no feat anymore, since they have so many dependencies. I don't even bother looking at these kind of competitions anymore, as the size requirement has no meaning anymore. Big, fat demos are more interesting that that aspect: what can you do if you don't have any limits? ASD is one of the key players in that area.

Here's a presentation from Notcon '04 which shows FMV on the ZX Spectrum, arguably even more limited than the original PC/XT:

https://www.youtube.com/watch?v=hhpN0vcHH9c

You can see the video itself around 6:30 in.

I remember seeing the first demos of streaming video off an XT back around '03/'04 iirc.

Friend of mine at the time had collected about four of the machines. Full-size disk drives are real beasts! Needless to say the project that never happened was to write a little program to control all four from a central PC by signalling over the unused serial pin or something... never happened, but would have been lots of fun.

Cool stuff and thanks for the link! :D

People used to write entire operating systems in that amount of code ;)

I sometimes switch my new Win8 machine to BIOS mode and boot FreeDOS from a USB stick and then run 8088flex with the /Q switch. No sound, but you can still see the videos.

If you have never played with libcaca, you might have fun with it: http://caca.zoy.org/wiki/libcaca It's a codec, essentially, and it's possible to connect it to VLC to play any video clip.

My original IBM PC won't boot anymore.

I recently tried my PC AT clone, the first time I applied power to it in probably 25 years. All I got was a loud beeping and a smell of burning electronics.

If you're interested in getting that clone running, most likely it's some elecrolytic capacitors (they're relatively colourful, and look like cans sitting on the circuit board) that degraded and failed. They are two pin devices, almost guaranteed through-hole at that vintage, and cheap to replace.

You may also be able to just replace the power supply, as it's usually the first thing to fail.

There are hundreds of caps on it, it may be a while before I figure out what went wrong :-)

On a related note, I bought a Carver stereo in the early 80's (M-200t amp and C-1 preamp). I run it every day all day. That's 30 years of daily use. And yet it still works like a champ (I replaced the on-off switch as it wore out). I guess they didn't use cheap caps in it!

A capacitor meter would make it quick!

A capacitor meter to test capacitors that are soldered onto an PCB?

https://en.wikipedia.org/wiki/ESR_meter

Or just look for swollen tops and leaks, which is probably all of them.

Electrolytic caps go bad when left unpowered for long intervals. The plates depolarize - but can be usually be restored by slowly raising the applied voltage. Gear that has been left off for years should be slowly powered up over a day or two in small steps with a variac.

Walter Bright! I remember Zortech C, and some micro cross compilers. Thanks.

Yeap. Most gear over 10 years old is likely to have this problem. Power supplies, TV, cheap a/v gear.

As an interesting note, I cracked open /A/D/S car amps and related gear from 1980's. Crazy engineering... No tantalum or electrolytics anywhere in sight. Props to whomever worked on that.

I never thought that that might be necessary. Thanks for the tip! But it's probably too late now anyway :-)

I was going to see what I had on that old AT hard disk.

I had a 486 that hasn't seen power since 1993. I tried powering that up, but the POST beeps suggested the keyboard controller had failed. Oh well. So I pulled out the drives, and my external IDE controller wouldn't recognize them. But my old Windows XP box's controller did, and I was able to read the old drives (200Mb and 500Mb respectively). It was kinda fun to see what detritus I'd left on them, but sadly no gold bullion.

That 486 was the last machine I had that would boot OS/2. Oh well! To the dustbin of history.

The EPROMs which were likely used to store BIOS and ROM BASIC were only rated for around 10 years.

Seeing that big heavy box and screen brings back some memories although ours was monochrome. Very impressive accomplishment.

Can't remember too much modex assembly, but ...

Does the CGA have a vsync non-display blanking interval that could prevent tearing?

In the video when he talks about future possible enhancements he mentions that the system timer could be set to provide an interrupt to use for page flips. So it sounds like the answer is technically no, but practically yes.

It looks like he's using text mode.

IIRC text on VGA (not this) has 4 pages and supports blanking interval stuff by virtue of VGA. 80x25 is 80x9 x 25x16 = 720x400. The character maps are actually 8x16 with the right pixel duplicated into the 9th. And in VGA there are two character planes (512 chars total), which explains Norton weird cursor that could go anywhere later copied by FreeBSD and others.

It maybe possible to change the character planes to be optimized for drawing. That would be cool.

So being horribly pedantic, but: That's a PC, not an XT.

Yes (assuming the author is correct in calling it a 5150), but it seems doubtful that a clip of any length would play on a stock, non-upgraded PC.

The demoscene guys can do a lot of stuff in 64K. It is not doubtful at all after you've seen one of the demos.

The 64k and 4k demos do a lot of pre-calculation to generate impressive imagery and sounds. The modern size-coded demos all take advantage of the massive processing power present in modern machines. This demo does the reverse—almost everything is precomputed and stored in a file format that is easy for the puny processor of the 8088 to play back at a decent frame rate. Without storage space (the demo requires a multi-megabyte hard disc on which to store the "video" file) the aproach would be a non-starter.

You probably don't remember but the demoscene started more than 20 years ago when the hw was very limited. The movies we're talking about last only a few tens of seconds at _very low_ resolution. You certainly don't need multi-megabyte storage for them

I know when and how the demo scene started. I have been involved with the scene most of my life and have several competition-rated productions to my name.

Read the damn article (and maybe my post) before being so condescending. The "8088 Corruption" demo is 9.3 megabytes.

It looks like an XT to me. The PC/XT looked identical to the original PC, except that the XT had one of the two floppy drives replaced with a 10mb hard drive. You can see that in the video at about 0:38: the floppy is on the left, the hard drive is on the right, with a light flashing on it as the data loads. (The next model, the PC/AT, looked different from the original PC.)

The author claims it's a 5150 (ie, a PC), and it's fairly reasonable to believe that it's an after-market hard drive.

To be fair, it seems to me that a lot of what's being displayed was rendered, if you will, on a more powerful machine. It seems to me a video was made on a modern machine and converted to a format for the IBM machine. I'm not saying this is a non-trivial process. But creating all this content on the IBM? I don't think so. Though I could be wrong.

Old hard drives... beep. I'd completely forgotten that part. Why did they make that beeping sound when you accessed them? Some sort of PWMed control of something? Heh, we used to joke that they were signaling our government overlords in morse code. Yeah, that used to be funny.

That was some serious nostalgia right there.

I believe the older hard drives used stepper motors to move the read head. Those can get quite musical when they're working hard.

i had one of them from a garage sale, it came with a joystick and tetris... so cool

Why does that, IBM XT, sound like yesterday? I mean it sounds like just yesterday?

surely not with flash.

Reply on news.ycombinator.com