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How to Back-up your PC *VisiCalc disk
_____________________________________
How to Back-up your PC *VisiCalc disk
Dual drive disk copy procedure:
The following technique will convert your Visicalc disk to a normal,
copyable disk. But don't try to add other files to the disk as there are
copyable
four programs on the disk which do not appear in the directory. Use of
this procedure does not relieve you of your responsibilities under copy-
right laws or licensing agreements. Using a PCDOS disk on drive A:,
Format a new disk on B:, then type what is underlined:
_____
A>DEBUG
As soon as DEBUG is loaded, remove the PCDOS disk from A:. Insert your
write-protected, "copy-protected" VisiCalc Disk in A: If you have at
least 96kb of memory, type what is underlined:
____________
-L 100 0 0 80 (reads first 16 tracks from A:)
_____________
-L 100 0 80 80 (reads next 16 tracks from A:)
_____________
-W 100 1 80 80 (writes same on B:)
______________
-L 100 0 100 3E (copies the last 8 tracks except
______________
-W 100 1 100 3E for the "uncopyable" sector 13F)
If you have less than 96KB, you must take smaller bites. Type the
following instead:
____________
-L 100 0 0 40 (read a 32KB "gulp", 8 tracks)
____________
-W 100 1 0 40
_____________
-L 100 0 40 40
_____________
-W 100 1 40 40
_____________
-L 100 0 80 40
_____________
-W 100 1 80 40
_____________
-L 100 0 C0 40
_____________
-W 100 1 C0 40
______________
-L 100 0 100 3E
______________
-W 100 1 100 3E
Remove your old VisiCalc disk from A:. You have now copied the disk, but
it won't run yet. First you must patch the 80-column VisiCalc program
loader/decrypter so that it will run correctly with sector 13F formatted
normally. type:
_____________
-L 100 1 138 3 (load the invisible loader-decrypter)
___________
-E 150 90 90 (first patch for 80-col.)
________
-E 156 B0
___________
-E 158 90 90
____________________
-E 168 90 04 40 90 90
___________
-E 16E C6 06
___________
-E 173 90 90
____________________
-E 179 90 04 20 90 90
___________
-E 17F C6 06
___________
-E 184 90 90
____________________
-E 18A 90 04 00 90 90
___________
-E 190 C6 06
________
-E 195 EB
____________________
-E 1B0 90 05 00 00 90 (last patch disables timer check)
_____________
-W 100 1 138 3 (save it back on new disk)
VisiCalc Backup 8-1-82 JEH Page 1
VisiCalc Backup 8-1-82 JEH Page 2
Next, you must apply the following patches if you wish to be able to run
VCONFIG to select the 40 column display, type:
_____________
-L 100 1 13B 3 (load 40-col loader-decrypter)
__________________________
-E 14D 90 90 B4 10 90 90 90 (first patch)
___________
-E 169 C6 06
___________
-E 16E 90 90
____________________
-E 174 90 2C 20 90 90
___________
-E 17A C6 06
___________
-E 17F 90 90
____________________
-E 185 90 2C 00 90 90
___________
-E 18B C6 06
________
-E 190 EB
____________________
-E 1AB 90 04 00 90 90 (disable timer check here too)
_____________
-W 100 1 13B 3 (save on new disk)
_
-Q (exit debug)
Remove your new copyable VisiCalc disk from B:. Write-protect the new
copy, place it in A: and boot it. After you have verified that the copy
works correctly, you may copy it using "DISKCOPY". All copies of the new
disk should function exactly as the original "copy-protected" disk. The
serial number is unchanged. You may not legally sell, give or loan either
the original disks, copies, or documentation!
Single drive note:
_
All DEBUG accesses to drive A: (L 100 0 x x) refer to the original
_
VisiCalc disk. References to drive B: (W 100 1 x x) refer to the new disk
being prepared. Make sure that you swap disks at the right time and that
your original disk has the write-protect tab installed.
Conversion to .COM file - single drive, 48KB minimum:
_____________________________________________________
Conversion to .COM file - single drive, 48KB minimum:
The following procedure will read the 80-column VisiCalc program from your
Visicalc disk (original or copy) and write a standard .COM file which may
be loaded on a non-standard disk drive (Winchester, double-sided, 8",
etc.). You will need another formatted disk. This disk should contain
the DOS system files (format /s) and any .BAT file (required to exit
VisiCalc sometimes). With a DOS disk in A:, type:
_____
A>DEBUG
Remove the DOS disk, insert your VisiCalc disk, then type:
_____________
-L 100 0 138 3 (load the VC80 loader/decrypter)
____________
-M 0 3FF 7000 (duplicate it in higher memory)
____
-R CS (inspect command segment register)
DEBUG will respond with the contents of the CS register (049F for DOS 1.0,
4B5 FOR DOS 1.1) and prompt with a colon :. Type the old contents + 700
(hex). That is, 0B9F or BB5. Do the same with RS. The screen should
appear as on the next page.
VisiCalc Backup 8-1-82 JEH Page 2
VisiCalc Backup 8-1-82 JEH Page 3
A>DEBUG
_____________
-L 100 0 138 3
____________
-M 0 3FF 7000
____
-R CS
CS 049F or CS 04B5 for DOS 1.1
____ ____
:0B9F or :0BB5
____
-R DS
DS 049F or DS 04B5
____ ____
:0B9F or :0BB5
Next, apply the following patches, type:
___________
-E 107 9F 04 (byte-flipped 049f from CS if DOS 1.0)
or
___________
-E 107 B5 04 (if DOS 1.1, byte-flipped 04b5)
_________________
-E 24D BB A8 00 90 (hard-wire the decryption key)
Now, to run the loader/decrypter, type:
__________
-G =1B8 26B (execute from 1b8 to 26b)
The entire program will now be loaded and decrypted and a register dump
should appear on the screen. Next restore CS and DS to their previous
values and set the file length in CX. The screen image should appear as:
(register dump)
____
-R CS
CS 0B9F or CS 0BB5 for DOS 1.1
____ ____
:049F or :04B5
____
-R DS
DS 0B9F or DS 0BB5
____ ____
:049F or :04B5
____
-R CX
CX 0000
____ ____
:6B64 (length = 6B64 FOR VisiCalc 1.1, 6802 for VC 1.0)
All that is left is to name the file, write it and exit. Remove the
VisiCalc disk, insert the new, formatted, empty disk in the same drive and
type:
________
-N VC.COM (or whatever you wish to name it)
_
-W (write the .COM file)
_
-Q (exit DEBUG)
THAT'S IT!
This document was placed in the public domain by me on August 1, 1982. I
do not know how many different "copy-protection" methods might be in use,
but this worked on my disk and should work on yours until VisiCorp changes
their recipe. Please feel free to distribute this information without
charge to any interested person.
John Hart
Houston, Texas