Power R Video Adapter

[Mac128]

I just picked up this Power R Inc. Macintosh SE video adapter, which I know Bunsen posted about earlier (but I can't seem to find it now):

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=270235874553

More on the Powerr archived webpage:

http://web.archive.org/web/19990819155946/www.powerr.com/prices.html

The question is, there's a DE-9 connector, but I was expecting a VGA

compatible connector. Does anyone know what kind of monitor can be

connected to this device? Do I need an additional adapter to further

convert to VGA? Given it was designed for the SE and presumably Apple monitors of the era, I was a little surprised that it didn't use the standard Apple DB-15 monitor connector, though it seems geared toward LCD presentation panels, so that might explain it.

These are the specs:

Power R Model 2703 Video Adapter for Macintosh SE and SE/30

Allows you to view your Macintosh display on LCD panels, LCD

projectors, external monitors and scan converters. Installs in minutes

with no cutting, drilling or soldering.

Specifications:

Resolution........................................ 512 x 342

Horizontal scan rate.......................... 22.3KHZ, (4µs on, 40µs off)

Vertical scan rate ............................. 60HZ (180µs on, 16.4ms off)

Output level (all lines) ......................TTL Positive

Video Connector Pins (pin out)........1-2 gnd; 3-4-5 RGB; 8 Horz; 9 Vert.

Power Consumption ........................0.25 watts from Mac power supply

 

[Charlieman]

The problem with the Power R is that it doesn't deliver a standard signal. Both the horizontal scan rate and the resolution are nothing like CGA or EGA, but may have overlapped with some monitors for other computers. But I suspect that many were modified displays for the Mac.

As I wrote several years ago at http://www.vintagemacworld.com/build_own.html, we need more information about old TTL monitors and adapters. I don't have a lot more concrete information today than when I wrote this:

"Chapter 8: Video display

This chapter is disappointingly short of detail -- the third party Mac display/video card market was thriving by this time but few options are mentioned. A kit for building a TTL adapter for 128 and 512 Macs (made by a company called ATS and presumably the same as the adapter mentioned in Larry Pina's book) and the Power R cable/adapter for compacts are discussed briefly. There is a reference to a series of "Hackintosh" articles in Computer Shopper, a US magazine, on homebrew TTL video adapter and monitor options -- does anyone have copies?."

Perhaps a few old magazine reviews will throw up information about displays that work with the Power R?

 

[Mac128]

The problem with the Power R is that it doesn't deliver a standard signal. Both the horizontal scan rate and the resolution are nothing like CGA or EGA, but may have overlapped with some monitors for other computers. But I suspect that many were modified displays for the Mac.

It sure looks like EGA, not that Wikipedia is infallible (God knows!). With 640x350 capable of accommodating 512x342 (whereas CGA doesn't) and a Horiz. freq. of 15.7/21.8 kHz (which is pretty close to 22.3). All that would be required of the Power R adapter would be accounting for the additional blank lines to drive a standard EGA monitor. Perhaps that's what it does.

I find it difficult to believe that Power R would use a standard so foreign all the way until 1994 with the Classic II without updating it by 1998 (note the date of the product list on the Powerr.com site and the specs on the Classic II adapter which are identical to the SE & Plus). VGA quickly became the standard following its introduction in 1987, with EGA having been around since 1984. I can certainly see even by the 1990 release of the Classic adapter, maintaining the EGA standard which would have accounted for most of the available displays on the market since 1984.

If that's the case, I need to find an EGA monitor to try it out on. Ebay? What am I looking for? If it is EGA, then shouldn't I be able to easily convert from EGA to VGA? Update: a quick Google search suggests there would be nothing easy about it as the sync rate and resolution would have to be compensated for. Assumed that with all the EGA video cards, a cheap adapter would have been available in order to upgrade monitors, something likethis custom item.

 

[Unknown_K]

Go find an old NEC 2D monitor, it should do EGA and VGA with the correct cable.

 

[Bunsen]

this Power R Inc. Macintosh SE video adapter, which I know Bunsen posted about earlier

Are you thinking of this thread?

I'll be happy to help in any way I can towards clonage. I'll go back and read the rest of this thread now.

 

[Bunsen]

Does anyone know what kind of monitor can be connected to this device? Do I need an additional adapter to further convert to VGA?

Adapter ... mmyeah ... something like that

This thread and the project linked from it will give you some idea of what's involved. Granted, it's going the other way, but the complexity would IMHO be of a proximate order of magnitude.

Luckily, you're now three clicks away from a supplier of monitors that might be usable as is.

These are the specs:

Which at first glance are all identical to the Mac itself.

Except wait WTF??

Video Connector Pins (pin out)........1-2 gnd; 3-4-5 RGB; 8 Horz; 9 Vert.

/edit/ I'm going to assume for the moment that the output is greyscale, and it is just necessary to have all pins connected.

Your mission should you choose to accept it is to post some better photos, scans preferably, of both sides of that device. See the Nubus Mafia pages at Applefritter.com for examples. Also, a trace of which pins on the connectors go to which points on the PCB would be handy.

 

[Bunsen]

it doesn't deliver a standard signal. / nothing like CGA or EGA

^-- What he said. Nothing like VGA either.

You need a monitor that can sync to the stated sync rates. And it needs TTL (Transistor to Transistor Level - basically binary +V or 0V) inputs, or you need to make a TTL to whatever converter.

Best bet is likely to be an -old- NEC Multisync (aka the video hacker's best friend) or a Commodore monitor (aka the video hacker's secret mistress). If you can get something capable of the stated sync rates, I think the conversion is fairly simple. I'll have a look for that site full of video conversion schematics /edit/ which would be:

http://www.epanorama.net/links/videocircuits.html

 

[Bunsen]

It is beginning to dawn on me that the simplest thing to attach this to would be another compact Mac CRT ...

At least for testing porpoises.

 

[Mac128]

Yes, Bunsen, that was the thread to which I was referring, thanks!

I think the adapter takes the Compact Mac video signal and converts it to TTL, which it then adapts to EGA. You both say it is not an EGA standard, but if the purpose of the adapter circuitry is to generate the extra scan lines to blank the top and bottom of the image to match EGA 640x350, wouldn't that then match the standard? Can the miniscule .4 difference between 21.8 and 22.3 kHz really make them entirely incompatible?

Not that it would be impossible, but why make an adapter that could only drive custom Mac displays, designed for just this adapter? Look at the old Power R site and you'll notice the Color Classic adapter manages to offer a VGA signal at 512x384 and 25.5 kHz, which also does not match VGA specs, so it must do something similar.

Thanks for the other link, I think reducing the VGA signal to lower scan rate is far easier than going the other-way, as evidenced by the numerous and inexpensive VGA to EGA cables to convert a VGA signal for use on an EGA monitor. The hard part is making it compatible with the compact Mac CRT. I found numerous LCD panels that are designed for legacy equipment and accommodate CGA, EGA & VGA, etc. input, but they are quite expensive. I also found a less expensive but still costly CGA to VGA converter and wondered why not an EGA version. Weren't CGA & EGA compatible?

UPDATE: Looking at the actual adapter, of which I shall post some pics, there are only 4 wires coming out of it and into the DE-9 cable. So what is that? H, V, G & monochrome signal split to the RGB pins?

 

[Bunsen]

A bunch of semi-random links of debatable utility

http://members.shaw.ca/novotill/RgbToMonochrome/index.htm

http://www.tkk.fi/Misc/Electronics/circuits/vga2rgbs.html

^- Tomi Engdahl seems to be the guru of this stuff

http://www.radiolocman.com/shem/search.html?rz=0226

http://www.inlineinc.com/tech/notes/technot3.htm

^- Scroll down some

http://www.repairfaq.org/sam/vidconv.htm

http://www.monitorworld.com/faq.html

 

[Mac128]

Here's the rear of the adapter. The identical set of pins in two rows at each end are the SE power connectors. The row of five pins alongside one edge is the DE-9 connector. The rest of the pins belong to a single black block, per the eBay pic, which seems to plug into the circuit board as a single unit. The only way to get more detail about the upper traces would be to disassemble it. Based on the pin configuration, it appears to contain the equivalent of two ICs and several other items between them. Whatever this actually does it is significantly more involved than a simple TTL adapter.

http://farm4.static.flickr.com/3259/2768848563_e5d2ecdfdb_o.jpg

 

[Bunsen]

I think the adapter takes the Compact Mac video signal and converts it to TTL, which it then adapts to EGA.

Why do you think this, when the manufacturer has told you specifically that it doesn't?

You both say it is not an EGA standard,

No we don't. The manufacturer's page that you linked says it isn't.

but if the purpose of the adapter circuitry is to generate the extra scan lines

Again, why would you think this, as opposed to wishing it?

Can the miniscule .4 difference between 21.8 and 22.3 kHz really make them entirely incompatible?

Who knows? First, find and catch your EGA monitor, then suck it and see.

why make an adapter that could only drive custom Mac displays, designed for just this adapter?

Because that was what the market was like at the time. Or at least Power R thought it was. You'll note that they're no longer in business.

Not everything that seems obvious to us looking back was obvious at the time. Even then, businesses and people can cling stubbornly to their own standards, while the rest of the industry standardises elsewhere. Look at Apple themselves, for example.

you'll notice the Color Classic adapter

is a completely different adapter from the one you have in your hand.

VGA to EGA cables

only connect a VGA card that can run in EGA emulation mode to an EGA monitor. They don't do any conversion themselves. They're just cables.
Sorry, wishing just isn't going to make it so. Ye canna change the laws o' physics, cap'n. They call these old beasts fixed frequency monitors for a reason.

That said, if you dig up an EGA monitor, give it a go. Don't forget though, you have two sync rates to consider, not just one.

 

[tomlee59]

I have one of these adapters, and they're very simple things. They don't have the smarts to "add extra scanlines" or do any format conversion of any kind. They just take the raw signals for the internal CRT, and do simple buffering and a couple of inversions. That's it. IIRC, the resulting signals are of the right polarities to interface to a TTL monitor, but the sweep rates are sufficiently off so that many TTL monitors will fail to sync.

 

[Mac128]

You both say it is not an EGA standard,

No we don't. The manufacturer's page that you linked says it isn't.

Actually I don't wish it to be so, I'm just trying to figure it out and speculating based on my understanding. And frankly I don't understand why you guys consider these two specs to be so vastly different.

Here's what I read about EGA on Wikipedia:

1 GND Ground

2 SR Secondary Red (Intensity)

3 PR Primary Red

4 PG Primary Green

5 PB Primary Blue

6 SG Secondary Green (Intensity)

7 SB Secondary Blue (Intensity)

8 H Horizontal Sync

9 V Vertical Sync

 

Signal

Type Digital, TTL

Resolution 640h x 350v x 16c, other modes available

H-freq 15.7/21.8 kHz

V-freq 60 Hz

Colors 16/64

And here's what the manufacturer says:

Specifications:

Resolution........................................ 512 x 342

Horizontal scan rate.......................... 22.3KHZ, (4µs on, 40µs off)

Vertical scan rate ............................. 60HZ (180µs on, 16.4ms off)

Output level (all lines) ......................TTL Positive

Video Connector Pins (pin out)........1-2 gnd; 3-4-5 RGB; 8 Horz; 9 Vert.

Power Consumption ........................0.25 watts from Mac power supply

When I compare the two, I see all of the pin signals line up, except for the intensity, one of which is a ground, the other two unassigned. Without any knowledge to the contrary, I would guess that a monochrome signal does not need intensity, that it applies only to color – why else would a monochrome TTL output supply RGB if not to be compatible with EGA? Then I look at the resolution and have to question whether the specs are visible area or actual area. I simply do not know, yet I know EGA will accommodate it. Finally, I see a mere .4kHz difference between the horizontal scan rate and wonder if that is tolerable.

Bunsen, since I do not know, I am asking in the form of speculation because I have not yet gotten a clear answer as to why the specs are totally incompatible when they seem so similar. You are the expert here, not me. So I apologize if it sounds like I am challenging you, in actuality I am encouraging further details. It's times like these when I wish I had an engineering background, but I don't. So I appeal to the collective membership for their good natured indulgence.

Your point is well taken that events of the past do not always make sense with what we now know, yet were perfectly sound at the time. Nevertheless, PowerR managed to make it into the 21st century, so all of their decisions weren't bad.

It would seem, based on your emphatic assertions that in any event this adapter is truly only compatible with specific LCD & CRT displays which used a unique standard to this adapter only. Which means the mission now is to try to locate them, or discover a way to adapt it further.

Finding a spare CGA or EGA monitor lying around is a bit more difficult to test it with, so I was simply trying to assess if it was even worth the effort. In any event, Bunsen, I bought the thing because it was in my hemisphere and would not have had to pay the colossal shipping you would have incurred and because you expressed an interest in finding out more about it. Now I'm wondering if I should have bothered.

 

[redrouteone]

Interestingly enough TTL monitors are still manufactured.

http://www.miraclebusiness.com/mt117.htm

Though they don't support the correct sync rates.

Thinking about it I think an EGA monitor will be you best bet. Though I don't think it will work out of the box. The built in controls might get you close enough to work at .4KHz out.

I would suggest taking a look at the service manual for some EGA monitors. They should mention the tolerance for the input signal and maybe some clue as how to change the input timing.

Another thought. A quick google shows there are a few VGA monitors that can sync that low. You might be able to cobble together a Digital Analog Converter out of a hand full of resistors. Then you could use a VGA monitor. http://www.play-hookey.com/analog/d2a_converter.html

 

[Bunsen]

So I apologize if it sounds like I am challenging you

I apologise if it seems like I'm challenging you. That's not my intention. God knows I've posted some far, far crazier speculative hack thoughts here. And the good folks of the MLA have helped me to sort out what is possible and what is not, and/or offered better ways of approaching the possibly possible to find out if it can work.

I'm just trying to do the same.

That and I have a vested interest - as I have the LCD panel section without the Mac adapter. So the more gets found out about these devices, the better for me

You are the expert here

:lol: :lol: :lol: :lol: :lol:

Nooooo, I'm just an interested amateur, like you. My background is in audio engineering.

why you guys consider these two specs to be so vastly different. / a clear answer as to why the specs are totally incompatible when they seem so similar.

It doesn't have to be vastly different to not work.

Put it this way: would you attempt to load and fire a .38 cal bullet in a .33? I mean, it's close enough, right?

My amateur, non-expert opinion is that EGA *might* be possible, but it won't be plug and play. You may have to modify the monitor. You may have to build an adapter circuit. Even if it can be got working, it may place strain on some of the monitor circuits (or not: remember, not an expert). And that you really, really need to go read the links I provided you.

There are different types of TTL signal. There are different types of sync. There are different polarities of sync. Just plugging one pin into another doesn't guarantee anything, and I encourage further research.

Here's what I read about EGA on Wikipedia: / And here's what the manufacturer says:

When I come back to this, I'll try and make up a table of these values so we can compare them side by side.

I was simply trying to assess if it was even worth the effort.

Good good, always a good first step.

In any event, Bunsen, I bought the thing because / you expressed an interest in finding out more about it. Now I'm wondering if I should have bothered.

Gosh, really? I apologise if my tone has put you off. I am trying to help here. I absolutely think this is the kind of mad, hare-brained, crazy hacking there should be more of around here. Whether it works or not, it's still worth the time to experiment and investigate.

The point that perhaps clumsily I was trying to make is that these things are not like software standards - they're hard wired into the equipment, and thus physical constraints. And that if you try to butt heads with physics, physics will win every time. And I don't want to see you getting into an asplodey magic smoke escaping situation.

That's not to say that with the right research, and a tweak here and there, it can't happen. I get that you're trying to see if CGA or EGA is worth the effort. My guess is "Maybe - it's certainly worth the effort of a bit of fact checking."

And it reminds me that I have a 22" monochrome EGA monitor I've been wondering what the hell to do with }

God speed, brave soldier!

 

[Charlieman]

It would seem, based on your emphatic assertions that in any event this adapter is truly only compatible with specific LCD & CRT displays which used a unique standard to this adapter only. Which means the mission now is to try to locate them, or discover a way to adapt it further.

Alas, Bunsen is correct about the monitor requirements. Back in the 1980s, it was very common for a secondary supplier to modify an OEM monitor. Many of the big Mac and Unix workstation analogue monitors were modified Sony SDM Trinitrons. Video standards barely existed, and it was easier to modify the monitor than to modify the display adapter. If you check the old adverts, you'll see how "standard video support" was so much of a big issue.

Power R created an adapter that converted a compact Mac video signal into TTL. Even the horizontal rate remained weird Mac-ness. Given that Power R were a big Mac developer at the time, we can assume that others modded monitors for it.

Note that although three RGB pins are connected, the adapter is for the SE and SE/30 which do not have built-in colour support. I presume that the connections are to help the connected display to sync. The SE/30 has Color QuickDraw, but requires a PDS adapter to display even greyscales.

Keep looking, as I do, for weird and wacky compact Mac monitors and video cards. To follow this project further, look out for one of the ancient NEC Multisyncs or similar, as suggested by Bunsen.

Redrouteone suggests that contemporary TTL monitors are available. This is true and Microvitec are one in Europe. Their Desk-Scan 1402 sounds like hacker's heaven all over again, but the input modifiers seem to be additional extras. I mention this monitor for one reason: there is a continuing market for old spec monitors, met by specialists, in order to maintain old medical and industrial control equipment.

Mac128, look for a monitor on eBay in the specialist categories. TTL with wide frequency and line tolerance, but as close as possible to the the Power R adapter. And then ask here.

Abstract question: Connecting a Power R to an NEC Multisync in analogue mode? Unless the TTL voltage is too high, it should display a viewable picture in strange colours?

 

[tomlee59]

TTL monitors of the sort used with the original IBM PCs can be modded to work with the PowerR adapter. The horizontal sweep frequency needs to be pulled a bit to guarantee sync. It's not hard to implement, once you've figured out what controls the sweep frequency. There are general meta-instructions in the ClassicMac pdf article. If you want to go that route, let me know, and I can provide some more specifics.

 

[Mac128]

... I have a vested interest - as I have the LCD panel section without the Mac adapter.

And it reminds me that I have a 22" monochrome EGA monitor I've been wondering what the hell to do with }

All good points. Too bad you are in Australia or we could be far more helpful to each other. So you have one of these oddball TTL LCD screens, or is it something like this which seems to be Multisync:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=280254596847