A MUlTiSCAN
MONiTOR FOR
ThE ClASSiC
ATARi
by LARRy P. WhiTE, AC CONTRibUTiNG AUThOR
80-Column Blues
First off, I have to warn you: his is not a "how-to-do-it" article. This is an article about my use of my Atari 8-bit and XEP80 with my particular monitor. You could damage both your XEP80 and your video equipment if you connect things improperly. Don't try this stuff unless you fully understand this article and have also read the related articles in this issue of AC.
When Atari announced the XEP80 back in 1987, I was overjoyed to hear that Sunnyvale at long last was providing 80-column capability for the 8-bit. I purchased the XEP80, then waited for something to use with it. When Atariwriter80 was finally released in 1989, I connected my XEP80 to my color composite monitor only to discover that it couldn't display 80 columns of text due to overscanning (see Bob Woolley's discussion of this problem in his "TTL Video for the Classic Atari" elsewhere in this issue). In addition, the text was illegible, which I guess was to be expected on a color monitor. Over the years I have seen a few composite color monitors that could produce reasonably legible text in 80 columns. Unfortunately, mine wasn't one of them! I also tried another (allegedly) 80-column composite monitor which produced legible text, but again overscanned the screen. I put the XEP80 in the closet. I waited all these years for this? Rats!
The Woolley Connection
Some time later, I came across an intriguing file titled "XEPIBM" by Bob Woolley in the SYSTEM UTILITIES section of CompuServe. After downloading, this looked like just the ticket for the XEP80! [Editor's Note: this file is an earlier version of Bob's TTL conversion article presented in this issue of AC. The version presented in this magazine is improved. - BP] By that time I had acquired a Mitsubishi Diamond Scan AUM-1381A multiscanning monitor. This is a true multiscanning monitor that has the ability to synchronize itself to a variety of incoming horizontal signal frequencies from the standard 15.75KHz of color TV all the way up to the 36KHz required by VGA. Figure 1 (from the Mitsubishi manual) shows all the inputs available on the rear of the unit.
| CRT |
13" Viewable 90 degree deflection 0.31 mm trio dot pitch Tinted glass, Non-glare P22, Medium-short persistence |
| Input Signal Comp. video
RGB video Sync. |
NTSC TTL Positive 8/16/64 Colors Analog 0.6 Vp-p positive Separate sync. TTL ±HD, ±VD Comp. syc. TTL ±HD/VD Comp. sync. on green video |
| Connector |
BNC Jack D-Sub 9-pin D-Sub 25-pin |
| Synchronization Horizontal
Verticle |
15.6 KHz to 36Khz (Automatically) 45Hz to 90 Hz(Automatically) |
| Resolution Horizontal
Vertical |
RGB TTL/Analog
Comp.Video 800 dots 500 TV lines 560 lines 350 TV lines |
| Display Area Horizontal
Vertical |
245 mm it is possible to 184 mm size control |
| Video Band Width |
30 MHz |
| Misconvergence |
Less than 0,4 mm (Centre) |
| Power Supply |
120 V, 60 Hz |
| Power Consumption |
85 W |
| Dimensions |
362(W) x 328(H) x 383(D) mm |
Weight |
14.5 kg |
Controls
Front
Back |
Contrast Brightness Power Switch Input signal switch Scan mode switch V-scanmode switch TTL color select switch Color saturation Tint Horizontal position Vertical position Horizontal size Vertical size |
AUM-1381A (from the Mitsubishi operator's manual).
I had already tried hooking the XEP80 to the composite (color) input, but this had produced unacceptable results. Would Bob's clever adaptation work?
Looking at the "Operation Manual" for my monitor, I noticed the digital (TTL) input would handle either CGA (16 colors), EGA (Enhanced Graphics Adapter, 64 colors), or MDA (TTL monochrome). The manual also had detailed pinouts for all the input connectors as well as a thorough description of the unit's performance specifications (shown in Fig. 2).
XEP80 To Multiscan
Adapting the XEP80 to my monitor posed minimal problems. However, Bob Woolley's modification instructions had to be translated for the input on the multiscanning monitor, which requires knowing what the pin descriptions actually mean. Also, there weren't any specifications available to me detailing the output signals and characteristic of the XEP80. Since the inputs on various multiscanning monitors are quite likely to be different, it's not possible to provide detailed information. Some interpretation is required, which is definitely more complicated than simply following a set of mod instructions. Still, the only real problem I encountered was minor difficulty making the solder connections to the bottom of the circuit board in the XEP80, as there was very little of the pins protruding through the board.
After completing the XEP80 TTL mods and connection to the TTL input on the AUM-1381A, I booted up AtariWriter-80. The full 80 columns was visible, but it completely filled the screen, border-to-border with the monitor display size turned as low as possible! I only hooked up the green input on the monitor, so essentially it is an 80 column "green-screen" display. The characters are very clear and crFip. They are tall and thin, typically 5 pixels wide by 8 pixels high in a 7x10 cell. The text looks very much like composite monochrome.
Having 80 columns definitely provides additional value for the 8-bit, but the difficulty in finding a suitable monitor shouldn't be discounted. In my setup, the size control is turned as low as possible in order to get all 80 columns on the screen (barely)! In the documentation for my XEP80, it lists the firmware as "Rev. 41.1" and the XE Handler as "Rev. 70.0". Those numbers suggest that a chronicle on the development of the XEP80 would make an interesting. Anybody?
To the best of my knowledge, AtariWriter-80 was the only software Atari ever released for the unit, and it came two years after the hardware. Having an 80-column wordprocessor is a decided advantage. Although AtariWriter80 does have its quirks (which have been pretty well catalogued in the pages of AC), it works reasonably well.
One Size Fits All
I originally bought a multiscanning monitor so I could connect my 1040ST and 130XE to a single monitor, since monitors consume lots of desk space. With its wide variety of inputs, the AUM-1381A is extremely versatile. Unfortunately, like nearly all PC-type monitors, it doesn't support sound, so the audio output of my Atari is connected to a small Radio Shack amplifier/speaker. With the popularity of sound boards for PC's, small amplified speakers are abundant. Many of these produce very good sound quality.
The AUM-1381A's composite input is a "BNC" connector, so an RCA-to-BNC adaptor (from Radio Shack) is required for the typical video connectors. The analog VGA (Video Graphics Array) input is a DB-25 connector, and the TTL input is the industry-standard DB-9 type. The unit has a full complement of user-adjustable controls to properly size and center the picture. The only drawback is that only the power switch, brightness, and contrast controls are front-mounted. All other controls and switches are on the rear panel.
The Mitsubishi's analog input worked perfectly with my ST's color (medium resolution) output. I had intended to install a switchbox and use the high resolution output of the ST but never got around to actually hooking it up.
Currently, my 130XE's 40-column output connects to the AUM-1381A's composite input, the XEP80 to the digital, and my home-assembled 386 clone goes to the Diamond Scan's VGA connector. As can be seen in the accompanying photograph (Fig. 3), the system still takes up a lot of desk space, but far less than if two monitors were used! I am and always will be an Atarian, but I just can't ignore the raw power of the PC both in terms of hardware and software. The range and sophistication of software is truly impressive! The only game I play on the PC is Golf, and you have to see 640x480 resolution, 256-color Golf to believe it: it's that good!
Still, for most games, hacking, and just plain fun, you just can't beat the classic Atari 8-bit! If you've seen any of the machine-language games from Europe recently, you'll agree they're generally more impressive than most anything released in the USA during the 80's. Programmers have continued to "push the envelope" on the 8-bit. So my trusty Atari still sees plenty of action. I frequently have both machines running and switch back and forth between them. And the Diamond Scan, it's absolutely great! A beautiful display and excellent flexibility!
Big Bucks Beastie
The Mitsubishi AUM-1381A multiscanning I purchased several years ago has been replaced by a newer model, the AUM-1391A. I haven't seen the newer model, but I'm told it's very similar to the 1381A and has an improved CRT using a smaller dot pitch for better color resolution (dot pitch on the AUM-1381A is .31mm). According to a Mitsubishi sales representative, the new AUM-1391A still accepts the same variety of VGA, digital, and composite inputs.
The Diamond Scan monitors are now distributed through Mitsubishi's Professional Electronics Group, which you can contact by calling toll-free 1-800-733-8439 for info on dealers in your area. Checking local vendor prices, I found the cost ranged from $515 to $620 excluding shipping. The $515 price is pretty consistent with the $469 I paid several years ago.
You're probably gasping at these prices. No doubt about it, multi-sync monitors are the most expensive type of monitor on the market. Is it the only option? I didn't make an investigation of monitors capable of this type of hookup, but I'm aware of at least one that accepts multiple inputs (see Ben Poehland's article "Super Video 2.1XL" for info on the Magnavox 1CM135). The most important thing to watch for when you're monitor-shopping is to ensure the unit you're considering will work properly with the signals from the source units you intend to use it with. And of course, you the user must be satisfied with the quality of resulting display!
