VOGONS


Art of CGA

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Reply 60 of 106, by Jo22

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reenigne wrote:
Our first family PC was an Amstrad PC1512 which had a clone CGA onboard. It didn't have a real CRTC so a lot of tricks were not […]
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Jo22 wrote:

For example, back in time. clone cards and Mono/Color combo cards were seemingly more common in Germany than IBM CGA cards, I believe.
Not sure about the UK, though or why it was that way at all (if it was, my memories are a bit sketchy).

Our first family PC was an Amstrad PC1512 which had a clone CGA onboard. It didn't have a real CRTC so a lot of tricks
were not possible, and it didn't have any improper modes either (I know, I tried all possible mode register values in an
attempt to find new modes). It used NTSC-compatible timings if I remember correctly, but didn't have any kind of omposite output.

Cool, the PC1512 was also popular over here! 😀 It was sold under the Schneider brand but was otherwise identical.
It wasn't until the Euro series (Euro PC, Euro AT, Tower AT, etc.) that they went their own ways. Luckily, the Amstrad PCW was also still sold here.
It was called Joyce and was an interesting "typewriter" running on CP/M. It was also occasionally seen in the Doctor Who series, I read.
My father had a PC1512, too. I believe it was his first IBM compatible machine that he got.
If memory serves, he upgraded it with a V30 processor (it was 8086 based) and used it to run his older
Z80 stuff he wrote for university via Z80MU, a popular CP/M emulator of the time. If he only knew about 22nice,
he could have used the 8080 emulation mode (minus the Z80 opcodes).
I also recall he liked 1512's graphics abilities and the GEM system that came with it.
In some way or another the PC1512 was like an "European Tandy", I think.
I read a bit about its CGA derivative at seasip. I'm not 100% sure, but I think I've heard
that the succesor of it, the PC1640 with EGA, still had that custom CGA circuit left intact on the PCB.
It was simply disabled somehow.. Anyway, I can't check, because I don't own such a system.

reenigne wrote:
Jo22 wrote:

The best we got in terms of CGA was CGA in 4 colours via RGB. On the bright side, this allowed many SCART-equipped TVs to be used as CGA monitors.

I never saw this but I have heard that it was done (at least sometimes the intensity bit was not wired up at all so you just got 8 colours). I seem to remember that the school BBC Micros in the late 80s (possibly also mid 80s) used SCART leads to connect to their monitors too.

I admit that XT hardware was a bit before my time, so I'm not 100 percent sure and have to speak under correction,
since I haven't seen that much of actual period-correct hardware from the original PC generations.
(Thankfully, I was allowed to still grew up with some CGA games, at least. 😁 )
My information was mainly based from what I heard from my father and his amateur radio friends.
Apparently, these custom SCART leads were popular to some degree here (also for other platforms, Commodore 128, etc).
I remember I've seen different schematics of that type a few times in these old radio magazines, too.
The CGA-SCART lead I remember of was printed in Elektor magazine. It was very simple.
And, as you mentioned, didn't take care of the intensity bit, so it was really just "RGB" (no RGBI).
If I had to guess, these SCART mods were probably kind of popular because people here had no proper CGA equipment,
but lots of clone cards from Taiwan. So people were happy with any picture output that was sharp and in colour.
Maybe the Commodore Amiga monitors also contributed to that, since they had RGB right from the start.
But that's pure speculation. As I said, it was a bit before my time. 😅

reenigne wrote:
Jo22 wrote:

Edit: I apologize for the long post. Just realized how long it really is. 😅
I hope you don't mind. I didn't mean to overrun your thread.
I'm too chatty sometimes (a bad habit of mine, my sister says).

No worries - if a thread drifts too far off-topic it can always be split off. I think this is all relevant though.

Whew!, glad to hear! 😀 More than often, I'm worried to overdo things because I like to share as much information as possible.
Partly it is also because, in my family, it's often my turn to entertain people (friends, relatives, acquaintances) that visit us,
because else the living room would become a quite place rather quickly (these people rarely bring in topics on their own sadly).
I guess that's why I developed that habit over time. That's why I'm often worried that people not knowing me personally,
especially folks over the internet, could mistaken me for having a bad personality or something like that, hah. 😅

emosun wrote:

[..] i have no idea if these will work on an older machine but they're fun to make [..]

Hi, yes, I believe so. That last picture seemed to work out nicely, IMHO.

Simply converted it to a CGA Binary without any further changes and then
displayed it with a BLOAD utility on an XT class machine with on-board CGA.

A short clip can be watched here (I zoomed in a bit) : https://youtu.be/ReaG6FmSlns

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"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 61 of 106, by emosun

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Jo22 wrote:

Hi, yes, I believe so. That last picture seemed to work out nicely, IMHO.

Simply converted it to a CGA Binary without any further changes and then
displayed it with a BLOAD utility on an XT class machine with on-board CGA.

hah thats sooo cool!. I made it in adobe and ms paint. it inspiring to see it actually work , makes me want to make more of them!

Reply 62 of 106, by reenigne

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Jo22 wrote:

I read a bit about its CGA derivative at seasip. I'm not 100% sure, but I think I've heard
that the succesor of it, the PC1640 with EGA, still had that custom CGA circuit left intact on the PCB.
It was simply disabled somehow.. Anyway, I can't check, because I don't own such a system.

I had thought it was just a different ASIC in the 1640, but I might be wrong.

I had a lot of fun with the 640x200x16 mode on the PC1512 - I even made a tile-based game engine that did 4-way scrolling using the start address register. Unfortunately because the mode is the same as the CGA's graphics mode from a CRTC perspective, the horizontal scrolling granularity is quite high (1/40 of the active screen width) so it was kind of fast and/or jerky. Also the machine didn't have the ability to have an extended virtual screen and I didn't know how to properly synchronize drawing new edge tiles with vsync so it was also kind of glitchy.

Reply 63 of 106, by emosun

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saw someone earlier looking for a miami vice in cga so i made this

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Reply 64 of 106, by Jo22

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reenigne wrote:

I had thought it was just a different ASIC in the 1640, but I might be wrong.

Or it's me who's wrong. 😀 I *think* I've read about this on one of these "old computers" databases.
You know, these which display pretty pictures of old machines and are sorted by model or manufacturer.
It was in the comment's section below where someone mentioned that, I think.
That's no reliable source, of course, but sometimes ex-users know more than Wikipedia..

For example, one user just told in the comments that the Sharp MZ-800 and MZ1500 were not the same.
If you search the net, most results will say that their only differences are colouring, PSU voltage, character set and place of release.
However, that person revealed that there's more. The whole graphics's sub system is/was different.
The MZ800 was sold in Europe and included an extra 640x200 mono colour mode (like CGA in Hi-Res mode) and only one PSG,
whereas the japanese MZ1500 had a colouful 320x200 mode and two PSGs (in addition both have retained the PC speaker from the MZ700/80K series).

reenigne wrote:
I had a lot of fun with the 640x200x16 mode on the PC1512 - I even made a tile-based game engine that did 4-way scrolling using […]
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I had a lot of fun with the 640x200x16 mode on the PC1512 - I even made a tile-based game engine that did 4-way scrolling using the start address register.
Unfortunately because the mode is the same as the CGA's graphics mode from a CRTC perspective, the horizontal scrolling granularity is
quite high (1/40 of the active screen width) so it was kind of fast and/or jerky. Also the machine didn't have the ability to have an
extended virtual screen and I didn't know how to properly synchronize drawing new edge tiles with vsync so it was also kind of glitchy.

That's very interesting! I was always curious about these modes. PC1512 and Plantronics were about the second popular modes after Tandy, I guess.
The Olivetti mode was also interesting, but rarely used by software (I opened a thread about it a few weeks ago).
I still wonder if that was a real gfx mode where all extra pixels were addressable, or just a line-doubled 640x200 mode..
Speaking of the 640x200x16 mode, by coincidence I had taken a releated video a few weeks ago, too.
It's about the french release of Maupiti Island, an interesting, not so popular adventure game.
Sadly, the screen recording didn't come out as intended. I used PCem on a CRT monitor, to make things more authentic.
In real life, it also worked very well. For some reason, however, the camera's focus had it's problems with it.
I reality, the picture looks lined/striped, not so blurred as seen on the video.
In my opinion, it looks very EGA-ish already. Comparable to Zeliard in EGA mode.

emosun wrote:

saw someone earlier looking for a miami vice in cga so i made this

Looks pretty! I'll take a picture of it with some real hardware and PCem. Maybe in 1-2 days.
- The little CGA monitor is boxed again, because I have little space in my room. 😅

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 65 of 106, by reenigne

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Jo22 wrote:
reenigne wrote:

I had thought it was just a different ASIC in the 1640, but I might be wrong.

Or it's me who's wrong. 😀 I *think* I've read about this on one of these "old computers" databases.

I've just been looking at the schematics, and indeed the PC1640 does seem to have an AMS40041 VDU IC just like the PC1512 does. I'm not sure what purpose it serves in that machine though. Mysterious!

Reply 67 of 106, by reenigne

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reenigne wrote:

I just sent an email to John Elliott - I think if anyone is likely to know, it'd be him.

John sent me this link to a newsgroup post by Roland Perry which confirms that, yes, indeed the 40041 in the PC1640 is vestigial - apparently it was just cheaper to build them that way!

Reply 69 of 106, by MobyGamer

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Okay, fine, here's my three interpretations of Dragon Strike's title screen: https://twitter.com/MobyGamer/status/989574722219315201

These were not done with CGAART although they very easily could have been. They were a response to the conversion the game did, which I felt could be improved on.

By "we need more CGA art" you might want to poke around old .PCX files you see on 1980s BBS archives. A lot of PC Paint and PC Paintbrush art was distributed that way for CGA before GIF was invented in 1987.

Reply 72 of 106, by dr.zeissler

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@jo22
The amstrads are nice indeed. In 1990 I knew someone who had the 1640 with ega.
But having the powersupply in the Monitor was not a good idea

Retro-Gamer 😀 ...on different machines

Reply 73 of 106, by JohnElliott

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reenigne wrote:
reenigne wrote:

I just sent an email to John Elliott - I think if anyone is likely to know, it'd be him.

John sent me this link to a newsgroup post by Roland Perry which confirms that, yes, indeed the 40041 in the PC1640 is vestigial - apparently it was just cheaper to build them that way!

In this thread you suggest that the 40041 is used to decode addresses for the RTC - maybe that's why it was simplest to leave it in for the PC1640.

Reply 74 of 106, by reenigne

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JohnElliott wrote:

In this thread you suggest that the 40041 is used to decode addresses for the RTC - maybe that's why it was simplest to leave it in for the PC1640.

Oh, well found/remembered! I had forgotten all about that. Yes, that makes a lot of sense. It's a sledgehammer to crack a nut but if you've got lots of the parts in stock and it saves having to rework part of the board I could see it being a money-saver just for that one function.

Reply 75 of 106, by Jinxter

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I would love to download all these pictures and display them on my Original IBM 5150 with the CGA Colour Monitor.
Is there a package to download?
Are there any dos/8088 viewers that can display these images?

Check out my YouTube channel: Retro Erik https://www.youtube.com/c/RetroErik
My collection: https://retro.hageseter.com

Reply 76 of 106, by reenigne

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Jinxter wrote on 2020-08-13, 12:04:

I would love to download all these pictures and display them on my Original IBM 5150 with the CGA Colour Monitor.
Is there a package to download?
Are there any dos/8088 viewers that can display these images?

I have a program ( https://www.reenigne.org/misc/cgadview.zip ) which can display most .cgad files generated by CGAArt on a 5150. A couple of my original images from the start of the thread (Sonic and Chameleon) require some more sophisticated code and CRTC trickery to display them because they aren't standard modes. I will have a go at putting together a slideshow package.

Reply 77 of 106, by ninjapig1212

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My apologies for resurrecting a old thread.

GYmuY71.png

Wanting to try viewing this 320x200 4 color image on actual vintage hardware, but I don't even have a TTL CRT monitor or CGA card yet.
Feeling very jealous of you gentlemen right now.

I think I will post more CGA images later.

Reply 79 of 106, by ninjapig1212

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MobyGamer wrote on 2021-08-01, 01:51:

That's excellent work. What program(s) did you use to create it?

Sorry about the late reply, I just saw your message.
I use photoshop, but there is a lot of manual editing and pasting going on so it's not exactly a automated process.

Here is another 320x200 4 color image.

HwdGrzB.png