What Is A Loader? – The Cassette Gazette Page 5

written by Matthew Reed

The Cassette Gazette was a 1983 one issue advertising newsletter that was a joint production of Lemons Tech and KWIK Software. The Gazette described the products sold by the two companies, mixed in with operational advice and interesting facts about using cassettes with your TRS-80. It appears to have been written by Wayne Lemons, the founder of Lemons Tech. The Gazette is reproduced here page by page with permission from Wayne Lemons' family.

What Is A Loader?

What’s a loader? As WE use the term, it means a hardware unit that plugs between the cassette recorder and the computer. Its job is to make tape loading reliable… BASIC, SYSTEM, KWIK or whatever.

Why LemonAid Loaders Work

All our loaders, including our newest PLUM, are technically designed for “friendliness” to the computer input.

For 500 baud and KWIK Model I the loader peaks, shapes, and smoothes the cassette output while removing ringing and noise. For this reason an individual pulse from the tape cannot “spread” (regardless of volume setting) into its neighbors territory, fouling up the timing or causing a pulse to be missed… either of which would bomb the program.

The difference between the regular signal-active LemonAid Loaders and the PLUM as described elsewhere, is in the sensitivity. Because the PLUM is powered it can sniff out weaker signals on the tape, even sometimes “rescuing” an “unloadable” tape. Also, the extra sensitivity lets the PLUM work with unmodified CTR 41 or CCR81 and with other recorders that have less signal output than the CTR80 or 80A. The PLUM is also compatible with the high baud rates of the Model III.

KOS Compatibility

We receive many inquiries about using either KOS3 or KWICOS with a low-RAM ‘system' program, most often referring to SCRIPSIT or the Editor-Assembler. Sorry, but it won’t work.

The KWIK cassette operating systems are primarily enhancements to Level II BASIC, and operate from the ‘immediate mode' (i.e.. from the READY prompt)… they are most helpful for the work-up and development of BASIC programs. This is why the KOSs are located in low RAM, and are made transparent to BASIC by moving the program storage area above the KOS. So if you also load in a low-RAM system program, it will overwrite the KOS and cause a system ‘crash.'

We have high-RAM versions of both KOS3 and KWICOS that would be compatible with low-RAM system programs, mainly for the ‘hybrid' (BASIC combined with machine code) programmer. But very few low-RAM “system” programs let you interact with BASIC. In other words, they won’t allow you go to READY and use BASIC, then return to the ‘system' program. The reason is simply that in almost all cases, the use of BASIC would overwrite part of the low-RAM system program, making it no longer useable. So even if you use Hi-RAM KOS, you can’t access it from the ‘other' program.

If the reason for wanting compatibility is ONLY to allow fast loading of the system program, it would be an over-kill to use the KOS simply as a ‘loader'… most of the KOS power would be unused and memory space needlessly wasted. For just “user” programs, it is much more efficient to use KWINK or KLOAN for making stand-alone copies of system programs, or KLOAD for Model I BASIC programs.

Also, the casual user may not realize that both SCRIPSIT and EDTASM contain their own ‘text' save and load routines, instead of using Level II ROM. So, even if KWICOS/KOS3 could be in memory at the same time, considerable changes would have to be made to the other program, just to link it to the KWIK speed routines and to change to KWIK format.

KWIK Taping For The TRS-80

The LemonAid loader by itself can’t let you transfer data to or from the tape faster than the standard 500 baud… simply because that’s the only speed the ROM routines can handle. To go faster, either the ROMs would have to be changed or new software routines loaded into RAM.

That’s where KWIK Software comes in… by adding new routines to the TRS-80 that give a new high-speed taping capability, plus many other new convenience and reliability features. Using only a standard cassette tape recorder, programs can be saved and loaded up to six times faster than before on the Model I, and 50% faster on the Model Ill. No modifications, chip changes, add-ons, interfaces, or special tapes or wafers are needed. Note: Early Model I’s that have received the XRX modification will not load faster than 1000 baud. KWIK Instructions include a simple alteration to the X2X, allowing taping at 3x to 6x speeds also. (See “XRX Mod.")

You can select the Model I tape transfer rate, from 2x to 6x (1000 to 3000 baud). Why? Quite reasonably, the faster the baud the narrower the allowable volume range for loading. If you don’t use a Loader you may not want to bother with the volume setting at the highest speeds, and so choose to use a lower baud. Also, if you choose not to ‘fix' your XRX mod first off, you can tape at double speed until you do. (Most users, though, fix the XRX and use 6x.)

A LemonAid Loader is not required for KWIK taping, but its use will greatly simplify all Model I loading… from standard 500 baud up the highest KWIK speed.

Which Program For What?

KWIK Programs are unique, and it may be difficult to determine from their descriptions just which program you need. To over-simplify:

KWICOS (Model I) and KOS3 (Model 3) are mainly “programmer’s programs,” most useful for:

  1. convenient and organized high-baud tape storage of BASIC programs, or ‘machine-code utility' programs (RENUM. etc.);
  2. writing, developing, work-up, and debugging of your own BASIC programs;
  3. saving, loading, and running of specialized programs written to take advantage of various KOS features;
  4. high-speed loading of a series of BASIC programs, such as an instruction course.

KWINK (Model I) and KLOAN (Model 3) make copies of standard (unprotected) SYSTEM programs, such as SCRIPSIT, EDTASM, LEVEL III, games, etc.

KLOAD and KNET (Model I) make stand-alone high-baud fast-loading copies of BASIC programs.

What’s On Your Tape?

Would you like to know what’s on a particular tape just by running it a few seconds and have it display the titles on the screen? You can, you know, for all tapes saved in KWIK format… even display the CTR counter reading where the program starts. The instructions tell you how. Or you can run through a whole tape and it will catalog the titles as it comes to the program, tell you whether it’s SYSTEM or BASIC, and if BASIC, tell you how many bytes in it.

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Categories: Cassette Gazette