TI Extended

One of the most popluar of the "Special Cartridges" the Extended Basic cartridge was a vast improvement over the BASIC which came loaded on the console. I won't go into a lot of detail here as the review below goes over all the changes. It pretty much became a standard, and many commercial software products required extended basic.

Extended Basic actually had two releases, the first being version 1.00, a few bugs were found and a second version was released, version 1.1, nothing was added, just fixed.

If you only owned one "Special Cartridge" then this was probably the one.......

For an Extended Basic programming reference go here.

  • More than 40 new or expanded commands, statements, functions, and subprograms.
  • Multiple-statement lines for speed and efficiency.
  • Sprite (moving graphics) capability.
  • Subprogram capability that lets you store commonly used subprograms on diskette for use as needed.
  • The ability to load and run one program from another.
  • Comprehensive program control of errors, warnings, and breakpoints.
  • Direct screen control of input and output.
  • Support for loading and running TMS9900 Assembly Language programs if the optional Memory Expansion unit (sold separately) is attached to the computer.

Extended BASIC Review
TI 99er, June 1981
Gary Kaplan

Nothing has caused as much excitement and anticipation in the Ti-99/4 community as the announcement (what now seems like an eternity ago) that an Extended BASIC would be forthcoming. Well, now that the new programming language is about to be gobbled up by hungry Home Computer users, the question on everyone's mind is, naturally enough, "Was it worth waiting for?"

For the answer to this, and to help put the new software in proper perspective, we first should examine TVs claim (in the introduction to the reference manual): "Texas Instruments Extended BASIC... bas the features expected from a high level language plus additional features not available in many other languages, including those designed for use with large, expensive computers." The key words here are "expected" and "not available." Features such as DISPLAY AT, ACCEPT AT, PRINT... USING, IMAGE, ON ERROR, multiple statement lines, expanded IF-THEN- ELSE statements, PEEK, Boolean operators, and assembly language subroutine calls are indeed "expected." Unfortunately, they were expected in the ordinary TI BASIC, since they're standard features of various Microsoft BASICs found in other machines. But just as plain, old, ordinary TI BASIC has its share of surprises that aren't commonly found in other BASICs (e.g., CALL SAY, RESEQUENCE, complete EDIT, TRACE, and BREAK utilities, plus its marvelously simple character definition and color assignment facilities), TI Extended BASIC too has its own unique bag of tricks not found on other machines. And this bag of tricks includes some mighty impressive feats of computing magic.

But before we get into these extended features,let's examine some of the obvious changes from TI-BASIC. First, there's the matter of a slight reduction in usable RAM. The maximum program size of Extended BASIC is 864 bytes smaller than TI BASIC. Although this represents only about a 6% reduction, any reduction in user memory is significant if it prevents certain applications from being RUN. And, in fact, as little as 500 bytes is frequently the critical amount of extra memory needed. [Witness the several programs in this issue that cannot be loaded or RUN with the disk controller's power turned on even with the CALL FILES(l) command that frees all but about 500 bytes for the disk system.) So programmers without the 32K RAM expansion, should try wherever possible to make up the loss with Extended BASICs built-in memory saving features: multiple statement lines [with more allowable characters per line), expanded IF-THEN-ELSE statements, multiple variable assignments, trailer comments that immediately follow statements (instead of separate REMs), repetition of strings with the RPT$ function, and the use of MIN and MAX functions.

The loss of user-definable characters in the character sets 15 and 16 is another departure from the TI BASIC standard. These custom characters are no longer available to programmers since the memory area is needed to keep track of sprites. Therefore, a TI BASIC program that doesn't use these character sets is supposed to RUN in Extended BASIC [Watch the next issue for an analysis of what is and isn't interchangeable.] in most circumstances-unless, of course, you've done something that will obviously cause trouble such as accidentally using a TI Extended BASIC key word as a variable in your TI BASIC program (e.g., DIG IT, ERASE, ERROR, IMAGE, MERGE, MAX, MIN, SIZE, WARNING, etc.)

Now, let's take a peek (no pun intended) into the "bag of tricks" I mentioned earlier. We'll cover only the highlights in this article; subsequent articles will take an in-depth look at the different features, and show you powerful and unique ways of using them.

A good place to start is with Extended BASIC's exciting new graphics capabilities. Nine new subprograms (plus 2 redesigned ones) provide the ability to create and thoroughly control the shape, color, and motion of smoothly moving, high-resolution graphics. These are the true sprites-graphics that can be displayed and moved at any of 49, 59 positions 192 rowsx 256 columns) rather than the /68 positions 24 rows x 32 columns) CALLed by the VCHAR and HCHAR statements of TI BASIC. But that's only the beginning. Sprites can be set in motion with simple X and Y velocity components, and will continue their motion without further program control; they can grow and shrink at will, be relocated or "hidden", and even pass over and blot out fixed objects and other sprites to give the illusion of depth and 3-D animation. [This is a function of the three-dozen stacked image planes of the Home Computer's video display processor chip-a unique graphics display that will be explained more fully in the next issue.

Although games aficionados and educators have every right to be overjoyed with the new sprites capability, TI-99/4 users who are more interested in business, scientific and professional applications ,' 0e drawn to other Extended BASIC features. First on the list is the impressive subprogram capability. Several options exist for communicating values (and entire arrays) between main and subprograms. There's also built-in protection to prevent a subprogram's Local variables from affecting the main variables. Additionally, commonly used subprograms may be SAVEd on a separate disk, and later MERGEd. This will allow programmers to build up an library of "universal" subprograms that can be called upon to supply the appropriate modules for new programming tasks-without time-consuming re-coding and debugging.

If this new subprogram flexibility is not enough for your most demanding tasks, how about "program chaining" -where one program can load and RUN another program from a disk. This means that multi-part programs of almost un/ira/ted size can now RUN on the T1-99/4 by breaking them into pieces and letting each segment RUN the next. And at any point in this chain, a "menu" may be inserted, allowing the user to choose with a single keystroke the particular program to be RUN. Imagine the possibilities.

Those of you with a speech synthesizer, or thinking of purchasing one, will be happy to learn that Extended BASIC includes a speech editor. You will no longer need the separate Command Module (with a retail price of about $45). What's more, with the combination of CALL SPGET, the capability of subroutine MERGEs, and the data for the code patterns (that TI supplies in the appendix of the reference manual), you can now easily add the suffixes ING, S, and ED to the roots of words in the resident vocabulary. And if TI ever supplies users with their master file of coded speech patterns and rules for combining them, it would be possible to create your own new words. As of now, they only provide the cryptic, "Because making new words is a complex process, it is not discussed in this manual."

Incidentally, this capability of having the computer say what you want it to say rather than being limited to a fixed vocabulary will, in fact, be implemented through a related approach. I'm referring to the "text-to-speech" capability of the forthcoming Terminal Emulator II Command Module which is programmable in TI BASIC. Since only one Command Module at a time can be attached to the T1-99/4, text-to-speech cannot be used with the Extended BASIC Command Module. I think it's safe to say, however, that we can expect to see TI solve this problem in the near future.

The final two features I'm going to cover in this overview provide a fair degree of software protection and open the door to additional language capabilities. Consequently, these are the particular features that may have the most profound impact on the entire T1-99/4 community-ultimately determining the quality and quantity of most of the commercial software produced for this machine.

Extended BASIC programs can be SAVEd in a PROTECTed form to guard against software piracy. This irreversible feature only allows a program to be RUN or loaded into memory with an OLD command. A program thus PROTECTed cannot be LISTed, EDITed, or SAVEd. If the program was originally SAVEd and PROTECTed on a disk, you still must use the protect feature of the Disk Manager Command Module to completely "lock up" the software by preventing it from being copied as well.

Extended BASIC has the capability to CALL and RUN assembly language programs if the 32K RAM expansion peripheral is attached to the computer. Since assembly language has a much faster execution speed than BASIC, many applications programs that are unfeasible to write in either TI BASIC or TI Extended BASIC (and Extended BASIC is not significantly faster than its predecessor) can now be written in TMS9900 assembly language, LOADed into the expansion memory periphe and RUN on a TI-99/4. This paves the way for some fancy sophisticated applications programs that now can be targeted for the TI-99/4 users.

Even though a TI-99/4 with Extended BASIC and the memory expansion can CALL and RUN assembly language programs and subroutines, it presently cannot be used towrite them. [Except for its "P-coded" version equipped with the UCSD Pascal DeveloprnentSystem as explained in this issue's related articles on third-party software development, and UCSD Pascal/Version 4.01 Alternately, it would have been helpful if TI had given Extended BASIC users the capability to POKE values into memory locations, but this feature was not implemented. Nevertheless, the door is now opened for a TMS9900 assembler [which TI will soon be marketing) that can be loaded into the expansion 32K RAM peripheral, and called up through Extended BASIC. Besides the obvious use of an assembler-being able to write programs or subroutines in assembly language--it does, in fact open up other exciting possibilities: "More exotic" languages can be specially written in TMS9900 assembly for T1-99/4 implementations. (FORTH and LISP hackers take note...)

The bottom line is more software tools for developers, and more economic incentive for them to produce valuable programs that can be protected against most piracy. This means that the T1-99/4 user community will be seeing a lot more useful software enter the market. Being able to run this software should more than justify the $100(retail) price for this filled-to-capacity 36Kbyte TI Extended BASIC Command Module with accompanying 224-page reference manual. Therefore, the answer to the title's rhetorical question, "How Extended Is Extended BASIC?" is apparently, "Extended enough..."