The Diablo 630. (evaluation) David H. Ahl.

We recently had the opportunity to conduct an extended use test of two Diablo printers, the Models 630 API and 630 ECS/IBM. The acronyms stand for, respectively, All Purpose Interface, Extended Character Set, and, of course, Big Blue.

Diablo Systems Inc. is the pioneering manufacturer of letter quality daisy wheel printers. For many years, most of their business was producing printers on an OEM basis for other manufacturers and system integrators. Indeed, as recently as two years ago, over 90% of Diablo's sales were to OEMs. Today, however, end users account for nearly 45% of Diablo's business. Still, you may well find yourself looking at a Diablo printer with someone else's name on it.

Over the years, the numbering system on Diablo printers has been somewhat confusing. The most popular models have been the 1620, 1640, 1650, Hytypte I and Hytype II. Frequently, software is advertised as being able to run on one or another of these printers. Unlike many computers we could name, Diablo has continued to use the same control codes in all their printers, hence, software written for earlier models will probably work on the currnt 630 models. Setting Up

The Diablo 630 comes in a box the size of a small house. Fortunately, most of the box is filled with a dense foam cushioning material; the printer is about the size of a wide carriage electric typewriter (23" x 19" x 10"). Still, this is big. Alongside a modern 80-column dot matrix printer, the Diablo 630 looks like a Peterbilt next to a Chevy Luv. The comparison is apt: four dot matrix pinters would fit in the same volume as the 630; the 630 is very solid and heavy; it is slow and fairly noisy, but is designed to produce high quality print day in and day out for years.

For your $2340, you get the printer itself, and a 30-page manual--that's it. To connect the API printer to a computer, you need a cable for another $89. Six cables are available to go between the 50-pin connector on the 630 and the following connectors: RS-232C; IEEE-488; IBM PC; Apple II or III; TRS-80 Model I, III, or 4; and Centronics 703.

The design is very clever as both the parallel and serial interfaces are contained in the Model 630 and API and it simply selects the active signal entering the 50-pin connector. Thus you could make up your own cable with both serial and parallel connectors (or even two different parallel connectors) for more than one computer. To do this, you would probably need to buy either the ECS API Interface Manual for $8 (describes pin assignments and signal definitions in detail) or the Interface Reference Manual (shows RS-232 cable diagrams for over 75 different computers).

The model 630 ECS/IBM is specially designed to work with the IBM PC and includes the connecting cable. The main difference between this printer and the 630 API is that it supports a special 192-character printwheel. there are two characters on each of the 96 plastic petals, and, in addition to rotating, the wheel jogs slightly to print the inner character. Carrying this process one step further, several printed characters require two stokes, accented letters, for example. In all, 241 separate characters can be printed (see Figure 1).

In addition to the cable, you must also purchase separately a print wheel and ribbon cartridge. The printer can handle either a plastic or metal daisy wheel. A metal wheel costs about $69 compared to $8 for a plastic one. Hoever, a metal wheel will last virtually forever whereas in heavy duty use of a plastic wheel will not last for more than two or three months.

Two flavors or ribbon are available, a 400' carbon film multi strike and a 60' nylon one. Both cost about $7 or $8.

Setting up the printer is very simple. First, you remove a few shipping restraint screws and tie wraps, install the black plastic paper rack on top, snap in a clear plastic sound panel, and plug in the cable to the 630 and your computer. A series of photos in the manual shows how to perform these steps as well as how to install the print wheel and ribbon carriage.

Following this physical setup, you must contend with two rotary switches and 16 DIP switches. All are conveniently exposed when the front cover is removed. Setting the switches is not as complicated as it might seem from looking at the manual. One rotary switch selects the type of print wheel while the other selects the pitch (10, 12, or 15 characters per inch, porportional spacing, or self-test).

The DIP switches select language (English, german, Etc.), baud rate, parity, auto linefeed, and printer ready protocol. You may have to try both positions of this last switch since most computer manuals are not clear as to whether the printer ready or DC1/DC3 protocol is used. The 630 manual describes this in some detail, but it was of little help we didn't know what any of our computers was expecting.

IEEE interface users will have to set another four DIP switches to specify the primary address. Again, this is described in much detail in the 630 manual.

It is probably a good idea to perform the self-test next. On page 13 in the API manual it states. "The Model 630 includes a provision for self-test." In page 14 is simple output from the self-test but in no place does the manual explicitly describe how to activate the test. Fortunately, the ECS/IB, manual corrects this oversight with a complete description of the self-test on page 28.

For normal operation, the setup is now finished and the printer is ready to go. However, it is also possible to teach the 630 some additional facts such as top, bottom, right, and left margins; tab stops; age length; and spacing. To do this involves manually spacing the printer to the code from the computer. This feature is probably of more use to the designer of a word processing package than to most end users, but if you want to get exotic with your output formating, the 630 has the capability. Powering Up and Printing

When the printer is buttoned up, the outside front panel has six indicator lights (power on, cover open, etc.) and seven touch sensitive switches (reset, linefeed, pause, etc.). In addition to lighting up the appropriate LED, error conditions also cause a brief warning beeper to sound.

Okay, so you have put in paper, rotated the platen to the top of a sheet, and are ready to go. What to print? Here is an idea suggested to me by Richard Vogler, senior product manager of Diablo. Print five or six full rows (132 characters) of capital H's.

This is a tough test of printer quality. The print density should be perfectly uniform from the beginnning to the end of the line, the line should be absolutely straight, and the vertical elements of each H should be of uniform density.

Here is a short program to do this: 10 FOR N=1 TO 5 20 FOR I=1 TO 132 30 LPRINT "H"; 40 NEXT I:LPRINT 50 NEXT N

How did the 630 stack up on this test? Pretty well, although it was not absolutely perfect. Density was uniform, the lines were straight, but occasional vertical elements were not quite uniform (see Figure 2){

Dick Vogler told me that the 630 could easily run faster than 40 characters per second, but Diablo quality control people demand absolutely perfect registration of characters on a line, thus they elected to limit the speed. Incidentally, the speed is quoted as being "up to 40 cps." The minimum speed is 32 cps with 10-pitch metal printwheel or extended character set plastic printwheel with no shifting. Naturally, printing characters that require two strikes of the ECS/IBM wheel slows print speed considerably.

In addition to a reich character set on the ECS printwheels, Diablo offers a wide assortment of standard wheels. EDP supply catalogs may lead you to believe there are about 12 choices of printwheels for the Diablo. Not so. The Diablo Type Boook lists over 200 printwheels. A sample of several common fonts is shown in Figure 3.

Depending upon the word processing package on your computer, the 630 is able to perform several special printing and formatting functions such as underlining bold face, strike over, subscripts, superscripts, and justification (see Figure 4).

Diablo is working closely with most of the major suppliers of word processing programs for the IBM PC to ensure that they will all support the 630 extended character set. to the user this would mean that when a character above ASCII 128 is used it will be displayed correctly on the screen even thoughit is typed with the control or alt mode key in combination with a letter. So far, the packages that will support this approach include Word Star, Peachtext, Easy Writer II, Volkswriter, and Word Plus-PC.

We tried several different word processing packages with the 630 ECS/IBM printer and had no trouble achieving the desired output. We also tried the 630 API with several different computer systems and word processing packages, including a home brew text formatting package that I wrote for the TRS-80 Model 100. Again, no problems.

The only computer with which the 630 did not function perfectly was the Olivetti M20 (it refused to execute a carriage return--ever). We suspect the problem is with the computer and not the 630.

On the other hand, the furnished RS-232 cable did not work with any of the computers we first tried. The reason for this was immediately apparent when we got the Interface Reference Manual; most computers require switching the connections to one or two pins or require two pins to be tied together. The computers with which the cable will work without modification are the Xerox 820, Heath/Xenith 89, Osborne 1, Northstar Advantage, and Apple with the Super Serial card.

Unlike the 1600 series Diablo printers, the 630 has a 1344-character buffer. This is about 190 words of 80% of a double-spaced page. This all but eliminates handshaking during printing since the computer can transmit bursts of text at the full baud rate. The baud rate can be set to 110, 300, 1200, or 2400; we settled on 1200 as a happy middle ground. Of course, an external buffer such as the Micro Fazer can be used between the computer and the printer.

The built-in buffer just doesn't forget anything. If the 630 halts during printing, say because the end of a ribbon has been reached, you can change, the ribbon, press reset, and the 630 will resume printing without missing a single character. In fact, there is no way of interrupting the print once the buffer is filled. If you find your program has produced a load of garbage that you don't want printed, your only recourse is to turn off the printer power. The functioning of the buffer, incidentally, is not described in the manual.

In addition to the standard text printing mode, two other print modes are available: graphics and vector plotting. While the operating codes for these features are listed in the manual, their use is not described, nor are there any programming examples (Diablo could take a lesson in manual writing from Epson). As a result, the user will have to turn to magazine articles to learn how to make full use of these graphics features. We tried the plotting program for the Diablo 1610 from the June 1979 issue of Creative Computing and, with a few minor changes, it worked like a champ.

Under normal circumstances, we would expect the 630 to be used with single sheets of paper; after all, it is a letter quality printer and letters are normally typed on lettehead. For high volume use, a single sheet feeder is available. This monstrosity clamps on the top of the printer and plugs into the back. We didn't try it, but we saw it demonstrated at NCC and it worked reliably.

However, we did try the tractor feeder. This also clamps on the top of the printer and has adjustable width tractors which can handle anything from 2-1/2" wide labels to 15" EDP paper.

The 630 has a two-position forms thickness switch which allows printing of up to six-part carbon forms. We tried printing a four-part form with excellent results. Reliability and Maintenance

The Diable 630 carries a 90-day unconditional warranty. If required, service during this period would be performed by the dealer which sold the printer. After that, you have a choice of service from the local dealer, four regional Diablo service centers, 200 Xerox service centers, or an independent service such as Sorbus. One year on-site service contracts from Sorbus cost about $300 and may be a good investment if the printer is to be put into continuous duty operation.

On the other hand, Diablo printers have a well-deserved reputation for reliable operation Our oldest Diablo printer is a 1641 which we have been using more or less continuously for nearly three years. Aside from periodic dusting and changing the printwheel and ribbon, it has never had a moment of downtime or required any service.

Compared to other daisy wheel printers, the initial cost of the Diable 630 is relatively high. However, amortized over the life of the unit, it begins to look like a bargain. The Bottom Line

The Diablo 630 is an evolutionary continuation of the high quality line of Diablo daisy wheel printers. It is rugged and designed for heavy-duty use. The clever use of different cables on the API model for interfacing to either parallel or serial computer ports means that it can be used with virtually any computer and will be ready for use when you upgrade your current computer. The ECS/IBM version is the only letter quality printer that produces the entire IBM PC character set.

Print quality is outstanding and printwheels are available for virtually any character set. The built-in buffer ensures that nothing will ever get lost, even if an error condition occurs.

The printer has excellent graphics capabilities (for a daisy wheel unit), however, the manual does not adequately describe the use of these features.

the excellent reliability of previous Diablo printers suggests that the 630 will have a long service life. However, service, if needed, is widely available. At around $2500 for printer, cable, printwheel, and ribbons, the 630 is not cheap, but given its expected long life, it may well be a best buy.

Products: Diablo 630 (computer apparatus)