Headland is the chipset. What did you do about the smell of faeces? 😵

133MHz wrote:

Headland is the chipset. What did you do about the smell of faeces? 😵

Savic Refresh'r Cat Accessory And Stain Cleaner. Desinfects and kills odours. I am a cat person (as you might infer from the nickname), so I always have one around. As it turns out, it's pretty good at neutralising various smells of non-feline origin as well. 🤣

Octek made good quality stuff. At least their 286 and 386 boards seem to be winners.

Anonymous Coward wrote:

Octek made good quality stuff. At least their 286 and 386 boards seem to be winners.

Excellent news! I really didn't know that brand, but if you're saying they were good in that time period, happy times.

Also, is it me or does their logo look a bit like Batman sign?...

Headland was a highly integrated chipset, including all the usual logic (8254 timer, 2x 8259 interrupt controller, 2x 8237A DMA controllers and support logic). It has very good performance.

I had bought Hercules graphics card (not an original one, sadly, but beggars can't be choosers) a while back, so I swapped it against Realtek VGA that was inside the Highscreen computer. Both cards side by side:

I have then connected old monitor with 9-pin connector to test the whole thing. And here I've hit the first hurdle: what I thought was EGA/CGA/HGC-compatible monitor started showing distorted starting screen upon powering the Highnote up. Whopsie-daisy!

I thought that maybe it got broken during his last stay in the closet, so I immediately tested it against EGA and CGA output. Fortunately, it works just fine. It just doesn't like the signal from Hercules card. So I am now stuck in a bit of a pickle (Rick!): perhaps the monitor can be tuned to operate with HGC, perhaps not, and if not, then I'll have to track down and buy proper Hercules-compatible device, which will be time- and quite possibly money-consuming as well.

TBC

Hercules is 18.425 kHz, CGA/EGA (lo-res) is 15.75 kHz. Because of that, a CGA/EGA monitor can not display Hercules (or MDA).

I see some text on that garbled picture so it's possible that the monitor might work with MDA if you adjust the horizontal hold control.

derSammler wrote:

Hercules is 18.425 kHz, CGA/EGA (lo-res) is 15.75 kHz. Because of that, a CGA/EGA monitor can not display Hercules (or MDA).

133MHz wrote:

I see some text on that garbled picture so it's possible that the monitor might work with MDA if you adjust the horizontal hold control.

Gentlemen, thank you kindly for your input. The overall consensus over the web is that CGA/EGA monitors can't display Hercules, just like derSammler wrote. That said, this monitor is a bit of an odd beast and has LEDs that show whether input signal is in 15kHz or 21kHz range:

This, coupled with what 133MHz observed, may suggest that there is still hope in making this combination of graphics card and monitor work. Or then again maybe not - 21kHz is not 18kHz either.

Now, when it comes to horizontal hold control, I assume you mean one of these:

But which one? There seems to be two - perhaps different controls for 21kHz and 15kHz? Also, pardon me for being totally green when it comes to monitors, but HOW do I adjust the control? It looks like a hole in the casing. Should I put my screwdriver in there? This sounds like a job for "i am putting my screwdriver everywhere" guy...

EGA uses 21kHz h-sync/60Hz v-sync in its native mode, 640x350.
Hence that mode is also used in text mode, I believe. 😀
Source: http://www.minuszerodegrees.net/mda_cga_ega/m … a_ega.htm#ega12

Hmmmm I wouldn't really touch the 15 and 21khz pots at the back , these are calibrated at the factory and if you mess with one it could affect the other setting and then you'll embark on a journey to fix it...
If you really need MDA then I can see 2 options:
- get a real mono mda monitor
- get the mce2vga converter and use a vga monitor with your hercules card

I think the same. I've got a few old TTL mono monitors. Got them a few years ago.
On eBay, look out for monitors with tems such as "TTL", "Philips", "Sanyo", "Mono", "Green Monitor", "Amber Monitor", etc.

keropi wrote:

get the mce2vga converter and use a vga monitor with your hercules card

This makes me think of my old Atari ST. It uses a digital mono signal that can be processed by analogue RGBHV (VGA) monitors.
A few years ago, I built a VGA cable for its hi-res mode (640x400). I wired syncs and fed the video signal to all three inputs.
If the VGA monitor is an LCD with TV tuner or an old multi-sync CRT, chances aren't bad it should work.
The whole NEC MultiSync series is good for these kinds of experiments, imho.

Schematic:
https://www.chzsoft.de/site/hardware/diverse- … a-nur-monochrom

Edit: Typos fixed.
Edit: Also look for monitor auctions containing the string "DIN" -
that's the round connector that was used for classic MIDI and the IBM keyboard connector, too.

I'd say there's still a glimmer of hope that it could work. I've successfully 'de-tuned' MDA monitors to run at CGA horizontal frequencies just by tweaking the H.HOLD control with no ill effects - at most you won't get a perfectly sized raster but it'll be more than satisfactory. These clone MDA/CGA/EGA monitors seem to be quite tolerant.

keropi wrote:

Hmmmm I wouldn't really touch the 15 and 21khz pots at the back , these are calibrated at the factory and if you mess with one it could affect the other setting and then you'll embark on a journey to fix it...

I disagree. First, it's a user-accessible control. Second, horizontal hold is the free-running frequency of the horizontal oscillator, it's a rather coarse/lenient adjustment since the oscillator is 'pulled in' to the correct frequency by a valid HSYNC signal - the free-running condition is totally normal and safe, and if you input some grossly mismatched HSYNC it simply won't lock on and keep free-running at a safe frequency, causing the familiar garbled picture (but no damage). Now there are some MDA monitors (like the IBM 5151) which lack a horizontal oscillator and they can indeed be damaged by a wrong HSYNC signal, but those by design lack a horizontal hold control, so if your monitor has an H.HOLD pot it's definitely not one of these. Last but not least after 25+ years of capacitor aging the oscillators have surely drifted, yet things still work (mostly) to spec.

TL;DR it's not a critical adjustment, it's safe to tweak and hard to mess up, and after 2+ decades it's probably drifted somewhat anyway.
Worst case scenario our little experiment won't work and the control can be reset to a working position.

OldCat wrote:

Now, when it comes to horizontal hold control, I assume you mean one of these: <snip> But which one? There seems to be two - perhaps different controls for 21kHz and 15kHz? Also, pardon me for being totally green when it comes to monitors, but HOW do I adjust the control? It looks like a hole in the casing. Should I put my screwdriver in there? This sounds like a job for "i am putting my screwdriver everywhere" guy...

You are indeed correct in your assumptions that one control adjusts the horizontal frequency for the 15kHz mode and the other is for the 21kHz mode, and you do stick a small screwdriver in there to adjust them. You can test which one is which by slightly tweaking one of them while displaying a picture - if the image shifts to either side you're on the one corresponding to that display mode. I'd tackle the issue like this:

• Identify which H.HOLD is which with a CGA/EGA picture (might be something logical like 1 for 15kHz and 2 for 21kHz but it never hurts to check).
• Input MDA video and check which mode LED is lit (I'd bet the 15kHz one since the 18k of MDA is closer to that).
• Tweak the corresponding H.HOLD control while watching the picture. If you get sync, congratulations! If you don't, return to CGA and re-adjust the picture.

If you're lucky and you get sync lock on MDA you could even try tweaking it back and forth between MDA and CGA so that you find a middle point where it syncs to both! (been there, done that) 😉

Oh! and you might also need to adjust V.HOLD too since MDA runs at 50Hz vertical instead of 60Hz (and you can also find the point where it locks to both 50 and 60 by itself).

Impressive, I've never thought that could work so well (I've only got a single CGA monitor). 😮
Say, is it also possible to connect an MDA/MGA card to a 15kHz PAL video monitor (without the intensity signal) ?
I'm asking, because resolution wise, both are quite similar (720x348 vs 720x576, both 50Hz vertical),

Jo22 wrote:

I'm asking, because resolution wise, both are quite similar (720x348 vs 720x576, both 50Hz vertical),

No, that's not possible, because MDA/Hercules are 720x348 non-interlaced, effective screen resolution. The full resolution is larger, because it includes borders (something like 882x420 if I recall correctly).
For PAL, 720x576 is 'maximum overscan', so including all borders. A 'normal' computer screen would have a resolution of about 640x512 on that, with borders.
Note also that this is an interlaced resolution, so the effective maximum resolutions are 720x288 and 640x256 respectively.
This difference in resolution explains why one has a pixel clock of 15 kHz, and the other of 18 kHz.

Thanks, Scali! I was previously looking for information about MDA beeing interlaced or not, but couldn't find any information regarding this.
I also made a mistake when I said PAL, I believe. I should have been more precise (PAL thinks in lines, so 720x576i rather is PAL "digital").
Also some of the older b/w video monitors can display 800 TV lines or more. I think I read this once when I saw some hi-res b/w security cameras sold on eBay. Anyway, that's not my subject, that's why I asked after all. 😅

Edit: Edited.

Gentlemen, thank you for your input. I will try to follow excellent instructions from 133MHz, but I am on a business trip, so the nearest possible opportunity is in one week. I will update the thread as soon as I have the chance.

You're welcome, good luck! 😀

PS: There's another way. too.
You can just do things the other way round.. 😉

shame your not local, ive got an amber hercules display sitting in my closet doing nothing