A tale of two discs

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Home / Publications / Rainbow / Rainbow 1981 / Rainbow 1981-12 - A tale of two discs

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A couple of months ago there were no disc systems available for the Color Computer. Now there are two. One, as was mentioned in the RAINBOW's November issue in a brief overview, is from Tandy and the other, also fairly recent in plans and announcement, is from Exatron -- the makes of the "Stringy-Floppy" system they advertise as the "poor man's disc."

We have yet to physically see an actual copy of the Exatron system (we've asked), although we have a pretty good understanding of its operation from a number who have. Frankly. we tried to get a review copy from them, but they were close-to-the-vest about it.

That doesn't color this review, however, and we provide that information only so you can judge the comments we make. Although the RAINBOW's policy is pretty strict about not reviewing unseen software or hardware (for your protection), we felt our information to be excellent on the Exatron -- we basically trust our source. — and we do have the Tandy system in hand. In view of the interest in discs, we present this information here.

We hope it will guide you if you are in the market for a disc system, now or in the future.

As previously reported, the Tandy disc system is based in ROM, except for about 2K for system RAM, file buffer allocation and file control blocks for the file buffers. This makes the "bottom of user RAM" start at about Hex DD4 rather than the familiar Hex 0600 (decimal 3540 instead of decimal 2441). The memory locations are allocated dynamically, depending on the number of file buffers you specify, so the available user memory could be less

By contrast, Exatron uses that 16K above the user area (so does Tandy for is Disc Operating System (DOS). Apparently, the buffers for Exetron are up there, too. However, Exatron allows the use of only 11 file buffers rather than Tandy's 15. While file buffers may seem to be something very "extra," we can certainly anticipate a number of applications when the extra ones Tandy provides would be extremely helpful.

Again, as to file buffers, Tandy automatically defaults to three — Exatron require. you to set then. It seems just another thin, to worry about.

To us, however, the biggest concern is the Exatron system supports single-density discs only. That's something like 87,000 bytes per disc. The Tandy system holds more than 157,000 bytes. A most significant difference! Perhaps Exatron -- which has a feature that allows conversion of Model I discs to Color Computer -- did it for this reason. However, it is, to our mind, a great waste of storage space.

We must say the DOS for both seems about the same There are the "SAVE", "RUN," "FORMAT," "BACKUP," "DIR (or) CAT," "COPY," "RENAME", "KILL" and other similar commands. As we reported last month, the DOS for Tandy is pretty much the same as for Model I-III. So is Exatron. You can "VERIFY" saves, load in either machine language or ASCII formats. Exatron does allow for

downloading ROM Carts. Tandy doesn't (but, since they sell them, you wouldn't expect them to). Tandy does allow you to set the record length while record lengths for Exatron are set at 255. Thus, you can "pack" more records in the Tandy system - and this is treated rather extensively in the excellent (as always) Tandy documentation.

In conversations with Exatron, I have been told they feel their RAM-based system superior, because it makes for easier updates. But the Tandy system can be upgraded by a new ROM chip. Given Tandy's support for its systems, we would expect there will be upgrades available as (and if) necessary.

Both directory listings leave a bit to be desired, without the full information you get with Model III or II. Also, neither system has password protection, disc names, invisible/no invisible files nor search through all drives (in a multi-drive system) for a specific file name. You have to specify the drive. However, you can designate the drive out of which you wish to operate.

Both systems are basically transparent to the user, which means you can pretty much run BASIC and not worry about the DOS until you want it. I think this is an advantage. If you have been saving data on tape, it's a fairly simple edit to change tape I/O to the disc I/O. Needless to say, the file transfer beats tape hands down!

As to price, the Tandy system is really less expensive -- and you can get the whole package in one box. Exatron sells the DOS system, but you need to order your drives elsewhere.

Documentation. We've only seen the preliminary Exatron version, and it seems to be good. As to Tandy, it is in the usual attractive Color Computer format. There are some gaps, particularly in the examples which have heavy emphasis on embedded data. The sample programs in the back work -- but. to get to something more sophisticated, you need to do a little programming on your own.

we're thoroughly satisfied with the Tandy disc. The Exatron - from what we been told and seen --appears a little more difficult to operate. Exatron does offer a couple of added features at added cost, but we don't really have good information on them, yet. If we get it, we'll pass it along.

Obviously, Exatron is a different system than Tandy. Our sources tell us most disc-based software will probably use the Tandy system, so there may be problems down the line if you go with something else.

There are a couple of things we do wish Tandy had included -- like an AUTO function, a few more utilities (perhaps using that upper 16K of RAM?) and we wish the controller itself was physically a little smaller. However, the system works flawlessly Use of the 2K of low RAM for some of the Tandy DOS does create some problems using their Machine Language programs, but, given Tandy's excellent support, we feel those will soon be solved, one way or the other.

From our extensive discussions, the Exatron system seems to work well, too. Single density discs and incompatibility may be a problem in the future, but time will tell.

As we receive more information on these systems -- and others -- RAINBOW readers will be kept up to date.

Y AN ALIEN·

6140 PRINT@301,"YOU LOSE"
6145 PRINT@361,"1,000  POINTS"
6150 PRINT@395,"EACH TIME!"
6155 PRINT:PRINT
6160 INPUT"TO CONTINUE PRESS <ENTER>";C$
6165 RETURN
7010 FORC=1TO13
7005 CIRCLE(G,175),C,4
7007 CIRCLE(G,175),C,2:NEXTC
7010 FORD=1TO13
7015 CIRCLE(G,175),D,3:NEXTD
7020 RETURN

Links

See this article as it appeared in the Rainbow Magazine 1981-12 Pag 3, in archive.org