Please Note: The information in this document has just been translated over from the printed version (14-Aug-98) and is being reviewed. There are errors! This notice will go away once all the obvious errors are corrected. From there, this document will be upgraded over time.

ALL ABOUT USING TAPE FOR DIGITAL STORAGE

Believe it or not, some Model T users still use cassette tape for file storage. That's okay, though. Properly used, tape is an inexpensive, dependable storage media; given the right tape recorder and proper file-storage techniques.

TANDY TAPE RECORDERS
Using a tape recorder as an auxiliary storage device for a digital computer requires that the tape recorder handle square wave without cutting or rounding out the corners of the "square" electrical signal. Recorders used for voice or music round out the corners and can not be used reliably for the storage and retrieval of digital data.

Tandy, Radio Shack sells a variety of tape recorders but only the CCR-82 was strictly designed for digital storage. The CCR-82 has a "P" position on the volume dial that kicks in the digital circuitry. The "P" stands for "program." Using other tape recorders requires "fiddling" with the volume control, or adding other electrical devices to the line, until a suitably-reliable setting is found.

Note: In all cases, even with digital tape recorders, multiple saves and loads are recommend to assure that saved files are retrievable.

TAPE
The best tape to use for digital storage is bottom to middle of the line tapes. Do not use high fidelity tape, metal tape, or tape designed for great music recordings. Tape designed for digital (computer) storage usually come without a leader; called "leaderless" tape. A "leader" does not contain oxide on 2 to 3 inches of its leading end, and thus will not storage magnetic images.

SAVING AND LOADING .DO FILES
The .DO file is created through the built in TEXT program or via a .BA, .CO, or ROM-based program that output's or append's to an open .DO file. The .DO file is usually comprised of ASCII character codes 1 thru 127 but may include the 8 bit high codes 128 thru 255 as well. Note: Character code 0 (null) is stripped from .DO files by the TEXT editor.

The .DO file takes more space on tape then .BA or .CO files but is the most reliably saved file on tape; due to the many blocks created during the save.

To save a TEXT file, go into the .DO file you wish to save. Tap your function key, respond with the name you wish to save the file you are currently into, as, and hit . To load a TEXT file, start by using TEXT to create a blank file using any name you wish--most tape users use the same name as the name of the file they will be loading. Next, once in the named/blank file, tap you function key, enter the name of the file as saved on tape, and hit .

SAVING AND LOADING .BA FILES
The .BA file includes codes from all 256 possible character code combinations, and thus is not an ASCII file. The .BA file must be saved and loaded through the built-in BASIC interpreter program.

To save a .BA file you must first be "in" the .BA file you wish to save, i.e., the target program file must be the current loaded program file in the BASIC interpreter, and you must be in there with it. This is accomplished in two ways.

Start the .BA file running and immediately the program, thus halting its operations, leaving you at the BASIC OK prompt. Or...

Go into BASIC and issue the commands:

NEW
LOAD"filename.BA

The OK prompt once again appears. At this position, regardless how you got here, you simply issue the command:

CSAVE"filename

To load a .BA file you must first be in the BASIC interpreter. Issue the commands:

NEW
CLOAD"filename

Once the OK prompt appears, thus the file has been loaded into BASIC from tape, you must save it to the menu. Do this by issuing the command:

SAVE"filename

Note: BASIC files previously saved to tape as .DO files may be read directly into the BASIC interpreter. However, BASIC program files previously saved to tape as .BA files may not be loaded directly into an open TEXT (.DO) file.

To save a .BA file as a .DO file, simply be "in" the halted BASIC program and issue the command:

SAVE"filename.DO

Lastly, use the technique addressed above to save the .DO file to tape. (see saving a .DO file)

SAVING AND LOADING .CO FILES
The .CO file is a compiled 8088 machine language file containing character codes 0 thru 255. And, like the .BA file, is not an ASCII file, and must be loaded and saved from within the BASIC interpreter.

The .CO file must be handled carefully. Each .CO file generates three numbers. These are known as the "Top:", "End:", and "Exe:" numbers; expressed as topnumber, endnumber, and exenumber.

To save a .CO file to tape you must first load it into BASIC. It is a wise idea to clean out any other .CO files that may be present. This is done via the BASIC command:

CLEAR0,MAXRAM

The next step is to...

LOADM"filename

...using the name of the .CO file currently in memory. When you issue this command, three numbers will be presented to you, i.e., the top, end, and exe numbers. Write these numbers on the tape jacket or tape reference card.

The last step is to issue the command:

CSAVEM"filename.CO",topnumber,endnumber,exenumber

To load a .CO file from tape you, once again, must be in the BASIC interpreter. And again, it's a good idea to clean out any current .CO files:

CLEAR0,MAXRAM

Next, you must reserve space in memory (RAM) to accept the incoming .CO file, load the .CO file from tape, then save it to the menu for use. Issue the commands as follows:

CLEAR256,topnumber
CLOADM"filename
SAVEM"filename.CO",topnumber,endnumber,exenumber