© 1983 by Lawrence I. Charters
Basic Computing, November 1983
MicroCompatible Cue
Model I/III, any configuration
MicroCompatible
P.O. Box 7674
Atlanta, GA 30357
(404) 874-8366
Every now and then a gadget comes along which, though simple in concept and operation, defies easy description. The MicroCompatible Cue is such a device: it does something so useful, vital, or extraordinary (depending on your needs) that it requires exceptional attention. Yet, like many great ideas, explaining what it does may cause consternation — why should something so simple require more than a few sentences to describe?
If you have a printer, serial or parallel, you can probably find a use for the Cue. Simply plug the Cue in to the parallel printer port on your TRS-80, plug your printer into the Cue, and start printing at, for all practical purposes, 3,000 c.p.s. (characters per second). If you have a serial printer and get a serial/parallel version of Cue, you can, again, plug the Cue in to your parallel (yes, parallel) port, plug your printer into the Cue, and be printing at 3,000 c.p.s. If you get one of the dual port versions of the Cue, you can share one printer among two computers, or attach a single computer to two printers – without bothering to plug and unplug a tangle of cables. As should be clear, the Cue does a number of things, but its most obvious use is as a print spooler.
If this sounds peculiar (and it may — “print spooler” is one of the more opaque examples of computer jargon), you might think of the Cue as a print buffer or print queue. And if this, too, sounds strange, think of the Cue as a mysterious black box. [Actually, a battleship-gray-bleached-black box?) Filled with 16K of RAM (32K optional) and controlled by a Z-80 microprocessor working with some clever ROM-based software, the Cue will accept data from your TRS-80 as fast as it can be sent, and then patiently send it to a printer at whatever plodding speed your printer requires. Meanwhile, back at the keyboard, you can do whatever you want while your printer bangs away. Unlike software-based spoolers, none of your computer’s resources — memory, time, or disk space — are used.
Now, about the 3,000 c.p.s. speed. Suppose you have a printer rated at 100 c.p.s. that you bought from $Budget Silicon$ during their Millard Fillmore Birthday Sale. After hooking up your printer, you decide to list your masterpiece, a 200 line coin-flip simulator. You soon discover that, even though 100 c.p.s. is probably about 99 c.p.s. faster than you can type, it drastically slows down your computer. While the program is being printed, your TRS-80 can do nothing else — for all practical purposes, you have a 100 c.p.s. computer.
With the Cue hooked up between your computer and printer, such delays are a thing of the past. You can send your coin-flip program off to your printer and be able to use your computer almost immediately. As far as your computer is concerned, everything has been printed, so you are free to run your coin-flip simulator and discover flaws in the laws of probability. Meanwhile, the Cue patiently feeds your listing to your printer. From your point of view, the computer is faster, the printer is faster, and (if you have something better to do than wait for your printout) you are faster.
Exactly how much faster is a good question. Several programs have been published to measure printer speed, and none will work with the Cue. One program indicated that the Cue operated at sixteen million characters per second, which appears a bit high. The figure of 3,000 c.p.s. was arrived at through casual, unscientific observation (it seems to takes about a second to transmit a 3,000 character Scripsit file), but even so is probably more accurate than 16M c.p.s.
For several months, I have tortured a P B16P Cue, MicroCompatible’s lowest priced model. It comes with 16K of RAM, one parallel transmit port, and one parallel receive port. Connecting it to any Radio Shack machine (except the Color Computer) takes all of thirty seconds: plug the Cue into a wall socket, connect the Cue’s receive port to the parallel port on the expansion interface, and connect a printer to the Cue’s transmit port. From that point on, operation is automatic. Up to 16,000 characters of information (Scripsit files, assembler or BASIC listings, VisiCalc worksheets, disk directories — anything you might want printed) can be “printed” in just a few seconds.
If you happen to have more than 16,000 characters of information to print (and in several months, I have run into this problem just a few times), the red pilot light on the Cue will go out, indicating the buffer is full. As soon as there is room for more data, the light will come on, the Cue will fill, the light will go off, and so on. Printing a 32,000 character Scripsit file with a 16K Cue will take only a third as long as without; if you are prone to long files, and this isn’t fast enough, you might consider a 32K model.
The Cue really shines when it is used in combination with programs that print intermittently. For example, using the Cue to “print” to Percom’s Electric Crayon allows you to draw pretty color pictures with the Crayon and, simultaneously, produce appropriate music on your TRS-80. Many accounts payable/accounts receivable, check-writing, and other business packages ask for information, digest it, print it, ask for more information, digest, print, etc. Without a Cue, such programs are often painfully slow: when something needs to be printed, everything grinds to a halt. With the Cue, there is no pause for printing, and jobs can be finished much faster.
To illustrate this point, I once wrote a program to create mazes, printing every line of the maze as it was generated. B.C. (Before Cue), the program took seventeen minutes to generate and print the largest scale maze — seventeen minutes in which the computer could be used for nothing else. Now, using the Cue, the program ties up the computer for just thirty-six seconds —- saving me more than fifteen minutes.
Other versions of the Cue can be used to solve compatibility problems. MicroCompatible’s “SP” series will take information sent from the parallel printer port and re-transmit it to a serial device — be it modem, printer, or whatever. (TRS-80 owners who have wondered how to send Scripsit files to serial printers should find this feature invaluable.) Serial versions of the Cue can also be used to buffer data to and from modems, preventing loss of information. Data can be sent to and received from the Cue at up to 9600 baud, freeing the computer for such functions as saving data to disk, looking at directories, printing files, and other tasks. Depending upon what you are doing, you may be able to save quite a bit of money in connect time and phone charges by using a serial Cue to link up to the Source or CompuServe.
For those among you who were raised on machine language, MicroCompatible states that serial versions of the Cue can be programmed, and they will sell you a guide on how this might be done. Just think: a pet computer for your TRS-80.
I have yet to have a problem with the Cue, though there are a few items which merit attention. Because the Cue operates independently of your TRS-80, it is im practical for use with cut-sheet paper (normal typing paper) unless you have an automatic cut sheet feeder. Printing a Scripsit document with the “P,P” command (print and pause between pages) will take just as much time with a Cue as without, since each sheet will still have to be fed in by hand and the “enter” key pressed for each new page.
Another problem can arise if you are printing a long document on roll paper, continuous forms, or tractor-feed paper, and something goes wrong. Since the Cue runs your printer independently from your TRS-80, there is no way to stop the printing from your keyboard. If you forget to line something up, or notice that your Scripsit file is right justified instead of left justified, or your VisiCalc worksheet is printing nothing but “Error,” you must turn the Cue off, wait ten seconds or so, and turn it back on in order to stop printing. This really isn’t serious, once you figure out what is happening, but the first time you try to stop printing and find the normal commands have no effect, you do wonder what kind of monster you have unleashed.
MicroCompatible also has problems with their documentation. When the PB16P arrived, there were no instructions —- not much of a hindrance, since both hook up and operation are fairly obvious. When I called MicroCompatible about this, they were quite embarrassed and immediately sent me a manual. The manual, though, is not exactly a masterpiece: it does not have any clear method of organization, appears aimed at a technical audience, and includes some rather amateurish hand-drawn diagrams. MicroCompatible states they are working on better documentation.
The fact that the Cue does allow you to do two things at once is, believe it or not, also a bit disconcerting. The first few times I printed something, I could not bring myself to use my computer, even though it was available, until the printer had stopped. I was so conditioned to wait for the printer that it took me a while to learn to take advantage of the Cue. Also, since the printer can be banging away while you are busy typing at the keyboard, you can’t hear the keys click, which might slow you down if you are used to their reassuring sound.
Microcompatible offers five versions of the Cue:
- MC16 P: 1 transmit, 1 receive parallel ports; 16K memory, $299
- MC16S: 1 transmit, 1 receive parallel ports; 16K memory, $349
- MC16SP: 1 transmit, 1 receive parallel ports; 1 transmit, 1 receive serial port; 16K memory, $399
- MC322P: 2 transmit, 2 receive parallel ports; 32K memory, $599
- MC322S: 2 transmit, 2 receive serial ports; 32K memory, $699
Any 16K model can be upgraded to 32K for an additional $150. MicroCompatible will also sell you (for $29-39 each) any cables required for connecting everything together. Considering that switch boxes (for connecting two printers to one computer) usually cost $90-200, and parallel to serial or serial to parallel converters usually cost $100-300, the prices are quite reasonable — especially since switch boxes and signal converters do not come with 16-32K of memory and their own Z-80.
Do your TRS-80 a favor. Buy it a pet computer.
MicroCompatible
P.O. Box 7674
Atlanta, GA 30357
(404) 874-8366