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+P2

This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.

Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.

Tape/disk: Home » Personal collection » Acorn ADFS disks » Electron_User_Group » EUG_38.ADF
Filename: +P2
Read OK: ✔
File size: 0EF5 bytes
Load address: 2B204556
Exec address: D3250
Duplicates

There is 1 duplicate copy of this file in the archive:

File contents
Examples:

Suppose you are in mode 2, and want to store the screen to a floppy. From
the table above, nnnn is 3000 and mmmm is 7FFF for mode 2. Therefore, to
save the screen under the filename "Screen", you would type:

*SAVE Screen 3000 7FFF

Now, if you want to restore the screen again, and put your graphics back
on the screen again, you would use *LOAD. Notice that this time only a
value for nnnn is required, and not for mmmm:

*LOAD Screen 3000

You can try this out now, if you switch on your Electron, and insert a work
disc into your floppy drive. If you use ADFS, you may need to use *MOUNT
to select the floppy disc, and be able to write to it. Now enter mode 2
by typing:

MODE 2

Now type some text on the screen which will represent the graphics which
you want to save. When you have finished, save the contents of screen memory
to floppy disk as shown above, by typing:

*SAVE Screen 3000 7FFF

When the disk drive has finished, clear the text off the screen by typing:

CLS

The text which you typed onto the screen has now been wiped from the
computer's memory, but should still be stored on the floppy disc. We can
show that this is so by typing:

*LOAD Screen 3000

Your text should now reappear on the screen. You can repeat this with any
kind of complex graphics on screen, and it will still work. The same can
be done in any other graphics mode, simply by changing the values of nnnn
and mmmm to those given in the table above. For example in mode 5 you
would use:

*SAVE Screen 5800 7FFF

followed by:

*LOAD Screen 5800 7FFF

There are, however, a few precautionary points which should be mentioned
about this technique of saving screen memory:

- As you probably realise, in four colour modes, the four colours you
can use can be changed from the default black, red, yellow and white by
using VDU 19 to change the palette. The colours in the palette are not
saved when this technique is used, and must be restored by repeating the
VDU 19 commands again. If you define the palette to, for example, black,
blue, cyan and white, and create a picture which looks good in this colour
scheme, you must remember that unless you define the palette to these four
colours before performing *LOAD to restore the picture, it may appear
rather odd when reloaded, as it will appear in black, red, yellow and
white - the default colour scheme.

- The exact reason why this happens is rather complicated, but if you
allow the cursor to go down off the bottom line of the screen, and allow
the screen to scroll up one line, this technique stops working until you
perform a MODE command, or clear the screen using CLS. Basically what
happens is that the computer does not physically move every line of text
on the screen up one line, but instead makes a note that every line in
screen memory is stored one line lower than it should be. When you reload
from disk, this note is lost, and the computer draws every line lower than
it should be. Each time that CLS or MODE is executed, screen memory is
cleared and reinitiated, so that every line is stored in memory where you
would expect it to be. Simply remember not to allow the screen to scroll
between clearing it, and saving the contents of screen memory to disc.

- The files created when you save the contents of screen memory to disk
are fairly large - so large, in fact, that you can often only fit around
15 such files onto each disk that you use (the exact number depends upon
what modes the images are in). Therefore this technique is not feasable
for a large number of images. Each screen in a game like Shipwrecked cannot
be stored in this way - if I had stored every screen of the game like this,
it would have required six floppy disks to store the data for the game!
This means that saved screens must be reserved for the purposes of title
screens only.


00000000  0d 45 78 61 6d 70 6c 65  73 3a 0d 0d 53 75 70 70  |.Examples:..Supp|
00000010  6f 73 65 20 79 6f 75 20  61 72 65 20 69 6e 20 6d  |ose you are in m|
00000020  6f 64 65 20 32 2c 20 61  6e 64 20 77 61 6e 74 20  |ode 2, and want |
00000030  74 6f 20 73 74 6f 72 65  20 74 68 65 20 73 63 72  |to store the scr|
00000040  65 65 6e 20 74 6f 20 61  20 66 6c 6f 70 70 79 2e  |een to a floppy.|
00000050  20 46 72 6f 6d 0d 74 68  65 20 74 61 62 6c 65 20  | From.the table |
00000060  61 62 6f 76 65 2c 20 6e  6e 6e 6e 20 69 73 20 33  |above, nnnn is 3|
00000070  30 30 30 20 61 6e 64 20  6d 6d 6d 6d 20 69 73 20  |000 and mmmm is |
00000080  37 46 46 46 20 66 6f 72  20 6d 6f 64 65 20 32 2e  |7FFF for mode 2.|
00000090  20 54 68 65 72 65 66 6f  72 65 2c 20 74 6f 0d 73  | Therefore, to.s|
000000a0  61 76 65 20 74 68 65 20  73 63 72 65 65 6e 20 75  |ave the screen u|
000000b0  6e 64 65 72 20 74 68 65  20 66 69 6c 65 6e 61 6d  |nder the filenam|
000000c0  65 20 22 53 63 72 65 65  6e 22 2c 20 79 6f 75 20  |e "Screen", you |
000000d0  77 6f 75 6c 64 20 74 79  70 65 3a 0d 0d 2a 53 41  |would type:..*SA|
000000e0  56 45 20 53 63 72 65 65  6e 20 33 30 30 30 20 37  |VE Screen 3000 7|
000000f0  46 46 46 0d 0d 4e 6f 77  2c 20 69 66 20 79 6f 75  |FFF..Now, if you|
00000100  20 77 61 6e 74 20 74 6f  20 72 65 73 74 6f 72 65  | want to restore|
00000110  20 74 68 65 20 73 63 72  65 65 6e 20 61 67 61 69  | the screen agai|
00000120  6e 2c 20 61 6e 64 20 70  75 74 20 79 6f 75 72 20  |n, and put your |
00000130  67 72 61 70 68 69 63 73  20 62 61 63 6b 0d 6f 6e  |graphics back.on|
00000140  20 74 68 65 20 73 63 72  65 65 6e 20 61 67 61 69  | the screen agai|
00000150  6e 2c 20 79 6f 75 20 77  6f 75 6c 64 20 75 73 65  |n, you would use|
00000160  20 2a 4c 4f 41 44 2e 20  4e 6f 74 69 63 65 20 74  | *LOAD. Notice t|
00000170  68 61 74 20 74 68 69 73  20 74 69 6d 65 20 6f 6e  |hat this time on|
00000180  6c 79 20 61 0d 76 61 6c  75 65 20 66 6f 72 20 6e  |ly a.value for n|
00000190  6e 6e 6e 20 69 73 20 72  65 71 75 69 72 65 64 2c  |nnn is required,|
000001a0  20 61 6e 64 20 6e 6f 74  20 66 6f 72 20 6d 6d 6d  | and not for mmm|
000001b0  6d 3a 0d 0d 2a 4c 4f 41  44 20 53 63 72 65 65 6e  |m:..*LOAD Screen|
000001c0  20 33 30 30 30 0d 0d 59  6f 75 20 63 61 6e 20 74  | 3000..You can t|
000001d0  72 79 20 74 68 69 73 20  6f 75 74 20 6e 6f 77 2c  |ry this out now,|
000001e0  20 69 66 20 79 6f 75 20  73 77 69 74 63 68 20 6f  | if you switch o|
000001f0  6e 20 79 6f 75 72 20 45  6c 65 63 74 72 6f 6e 2c  |n your Electron,|
00000200  20 61 6e 64 20 69 6e 73  65 72 74 20 61 20 77 6f  | and insert a wo|
00000210  72 6b 0d 64 69 73 63 20  69 6e 74 6f 20 79 6f 75  |rk.disc into you|
00000220  72 20 66 6c 6f 70 70 79  20 64 72 69 76 65 2e 20  |r floppy drive. |
00000230  49 66 20 79 6f 75 20 75  73 65 20 41 44 46 53 2c  |If you use ADFS,|
00000240  20 79 6f 75 20 6d 61 79  20 6e 65 65 64 20 74 6f  | you may need to|
00000250  20 75 73 65 20 2a 4d 4f  55 4e 54 0d 74 6f 20 73  | use *MOUNT.to s|
00000260  65 6c 65 63 74 20 74 68  65 20 66 6c 6f 70 70 79  |elect the floppy|
00000270  20 64 69 73 63 2c 20 61  6e 64 20 62 65 20 61 62  | disc, and be ab|
00000280  6c 65 20 74 6f 20 77 72  69 74 65 20 74 6f 20 69  |le to write to i|
00000290  74 2e 20 4e 6f 77 20 65  6e 74 65 72 20 6d 6f 64  |t. Now enter mod|
000002a0  65 20 32 0d 62 79 20 74  79 70 69 6e 67 3a 0d 0d  |e 2.by typing:..|
000002b0  4d 4f 44 45 20 32 0d 0d  4e 6f 77 20 74 79 70 65  |MODE 2..Now type|
000002c0  20 73 6f 6d 65 20 74 65  78 74 20 6f 6e 20 74 68  | some text on th|
000002d0  65 20 73 63 72 65 65 6e  20 77 68 69 63 68 20 77  |e screen which w|
000002e0  69 6c 6c 20 72 65 70 72  65 73 65 6e 74 20 74 68  |ill represent th|
000002f0  65 20 67 72 61 70 68 69  63 73 20 77 68 69 63 68  |e graphics which|
00000300  0d 79 6f 75 20 77 61 6e  74 20 74 6f 20 73 61 76  |.you want to sav|
00000310  65 2e 20 57 68 65 6e 20  79 6f 75 20 68 61 76 65  |e. When you have|
00000320  20 66 69 6e 69 73 68 65  64 2c 20 73 61 76 65 20  | finished, save |
00000330  74 68 65 20 63 6f 6e 74  65 6e 74 73 20 6f 66 20  |the contents of |
00000340  73 63 72 65 65 6e 20 6d  65 6d 6f 72 79 0d 74 6f  |screen memory.to|
00000350  20 66 6c 6f 70 70 79 20  64 69 73 6b 20 61 73 20  | floppy disk as |
00000360  73 68 6f 77 6e 20 61 62  6f 76 65 2c 20 62 79 20  |shown above, by |
00000370  74 79 70 69 6e 67 3a 0d  0d 2a 53 41 56 45 20 53  |typing:..*SAVE S|
00000380  63 72 65 65 6e 20 33 30  30 30 20 37 46 46 46 0d  |creen 3000 7FFF.|
00000390  0d 57 68 65 6e 20 74 68  65 20 64 69 73 6b 20 64  |.When the disk d|
000003a0  72 69 76 65 20 68 61 73  20 66 69 6e 69 73 68 65  |rive has finishe|
000003b0  64 2c 20 63 6c 65 61 72  20 74 68 65 20 74 65 78  |d, clear the tex|
000003c0  74 20 6f 66 66 20 74 68  65 20 73 63 72 65 65 6e  |t off the screen|
000003d0  20 62 79 20 74 79 70 69  6e 67 3a 0d 0d 43 4c 53  | by typing:..CLS|
000003e0  0d 0d 54 68 65 20 74 65  78 74 20 77 68 69 63 68  |..The text which|
000003f0  20 79 6f 75 20 74 79 70  65 64 20 6f 6e 74 6f 20  | you typed onto |
00000400  74 68 65 20 73 63 72 65  65 6e 20 68 61 73 20 6e  |the screen has n|
00000410  6f 77 20 62 65 65 6e 20  77 69 70 65 64 20 66 72  |ow been wiped fr|
00000420  6f 6d 20 74 68 65 0d 63  6f 6d 70 75 74 65 72 27  |om the.computer'|
00000430  73 20 6d 65 6d 6f 72 79  2c 20 62 75 74 20 73 68  |s memory, but sh|
00000440  6f 75 6c 64 20 73 74 69  6c 6c 20 62 65 20 73 74  |ould still be st|
00000450  6f 72 65 64 20 6f 6e 20  74 68 65 20 66 6c 6f 70  |ored on the flop|
00000460  70 79 20 64 69 73 63 2e  20 57 65 20 63 61 6e 0d  |py disc. We can.|
00000470  73 68 6f 77 20 74 68 61  74 20 74 68 69 73 20 69  |show that this i|
00000480  73 20 73 6f 20 62 79 20  74 79 70 69 6e 67 3a 0d  |s so by typing:.|
00000490  0d 2a 4c 4f 41 44 20 53  63 72 65 65 6e 20 33 30  |.*LOAD Screen 30|
000004a0  30 30 0d 0d 59 6f 75 72  20 74 65 78 74 20 73 68  |00..Your text sh|
000004b0  6f 75 6c 64 20 6e 6f 77  20 72 65 61 70 70 65 61  |ould now reappea|
000004c0  72 20 6f 6e 20 74 68 65  20 73 63 72 65 65 6e 2e  |r on the screen.|
000004d0  20 59 6f 75 20 63 61 6e  20 72 65 70 65 61 74 20  | You can repeat |
000004e0  74 68 69 73 20 77 69 74  68 20 61 6e 79 0d 6b 69  |this with any.ki|
000004f0  6e 64 20 6f 66 20 63 6f  6d 70 6c 65 78 20 67 72  |nd of complex gr|
00000500  61 70 68 69 63 73 20 6f  6e 20 73 63 72 65 65 6e  |aphics on screen|
00000510  2c 20 61 6e 64 20 69 74  20 77 69 6c 6c 20 73 74  |, and it will st|
00000520  69 6c 6c 20 77 6f 72 6b  2e 20 54 68 65 20 73 61  |ill work. The sa|
00000530  6d 65 20 63 61 6e 0d 62  65 20 64 6f 6e 65 20 69  |me can.be done i|
00000540  6e 20 61 6e 79 20 6f 74  68 65 72 20 67 72 61 70  |n any other grap|
00000550  68 69 63 73 20 6d 6f 64  65 2c 20 73 69 6d 70 6c  |hics mode, simpl|
00000560  79 20 62 79 20 63 68 61  6e 67 69 6e 67 20 74 68  |y by changing th|
00000570  65 20 76 61 6c 75 65 73  20 6f 66 20 6e 6e 6e 6e  |e values of nnnn|
00000580  0d 61 6e 64 20 6d 6d 6d  6d 20 74 6f 20 74 68 6f  |.and mmmm to tho|
00000590  73 65 20 67 69 76 65 6e  20 69 6e 20 74 68 65 20  |se given in the |
000005a0  74 61 62 6c 65 20 61 62  6f 76 65 2e 20 46 6f 72  |table above. For|
000005b0  20 65 78 61 6d 70 6c 65  20 69 6e 20 6d 6f 64 65  | example in mode|
000005c0  20 35 20 79 6f 75 0d 77  6f 75 6c 64 20 75 73 65  | 5 you.would use|
000005d0  3a 0d 0d 2a 53 41 56 45  20 53 63 72 65 65 6e 20  |:..*SAVE Screen |
000005e0  35 38 30 30 20 37 46 46  46 0d 0d 66 6f 6c 6c 6f  |5800 7FFF..follo|
000005f0  77 65 64 20 62 79 3a 0d  0d 2a 4c 4f 41 44 20 53  |wed by:..*LOAD S|
00000600  63 72 65 65 6e 20 35 38  30 30 20 37 46 46 46 0d  |creen 5800 7FFF.|
00000610  0d 54 68 65 72 65 20 61  72 65 2c 20 68 6f 77 65  |.There are, howe|
00000620  76 65 72 2c 20 61 20 66  65 77 20 70 72 65 63 61  |ver, a few preca|
00000630  75 74 69 6f 6e 61 72 79  20 70 6f 69 6e 74 73 20  |utionary points |
00000640  77 68 69 63 68 20 73 68  6f 75 6c 64 20 62 65 20  |which should be |
00000650  6d 65 6e 74 69 6f 6e 65  64 0d 61 62 6f 75 74 20  |mentioned.about |
00000660  74 68 69 73 20 74 65 63  68 6e 69 71 75 65 20 6f  |this technique o|
00000670  66 20 73 61 76 69 6e 67  20 73 63 72 65 65 6e 20  |f saving screen |
00000680  6d 65 6d 6f 72 79 3a 0d  0d 2d 20 41 73 20 79 6f  |memory:..- As yo|
00000690  75 20 70 72 6f 62 61 62  6c 79 20 72 65 61 6c 69  |u probably reali|
000006a0  73 65 2c 20 69 6e 20 66  6f 75 72 20 63 6f 6c 6f  |se, in four colo|
000006b0  75 72 20 6d 6f 64 65 73  2c 20 74 68 65 20 66 6f  |ur modes, the fo|
000006c0  75 72 20 63 6f 6c 6f 75  72 73 20 79 6f 75 0d 63  |ur colours you.c|
000006d0  61 6e 20 75 73 65 20 63  61 6e 20 62 65 20 63 68  |an use can be ch|
000006e0  61 6e 67 65 64 20 66 72  6f 6d 20 74 68 65 20 64  |anged from the d|
000006f0  65 66 61 75 6c 74 20 62  6c 61 63 6b 2c 20 72 65  |efault black, re|
00000700  64 2c 20 79 65 6c 6c 6f  77 20 61 6e 64 20 77 68  |d, yellow and wh|
00000710  69 74 65 20 62 79 0d 75  73 69 6e 67 20 56 44 55  |ite by.using VDU|
00000720  20 31 39 20 74 6f 20 63  68 61 6e 67 65 20 74 68  | 19 to change th|
00000730  65 20 70 61 6c 65 74 74  65 2e 20 54 68 65 20 63  |e palette. The c|
00000740  6f 6c 6f 75 72 73 20 69  6e 20 74 68 65 20 70 61  |olours in the pa|
00000750  6c 65 74 74 65 20 61 72  65 20 6e 6f 74 0d 73 61  |lette are not.sa|
00000760  76 65 64 20 77 68 65 6e  20 74 68 69 73 20 74 65  |ved when this te|
00000770  63 68 6e 69 71 75 65 20  69 73 20 75 73 65 64 2c  |chnique is used,|
00000780  20 61 6e 64 20 6d 75 73  74 20 62 65 20 72 65 73  | and must be res|
00000790  74 6f 72 65 64 20 62 79  20 72 65 70 65 61 74 69  |tored by repeati|
000007a0  6e 67 20 74 68 65 0d 56  44 55 20 31 39 20 63 6f  |ng the.VDU 19 co|
000007b0  6d 6d 61 6e 64 73 20 61  67 61 69 6e 2e 20 49 66  |mmands again. If|
000007c0  20 79 6f 75 20 64 65 66  69 6e 65 20 74 68 65 20  | you define the |
000007d0  70 61 6c 65 74 74 65 20  74 6f 2c 20 66 6f 72 20  |palette to, for |
000007e0  65 78 61 6d 70 6c 65 2c  20 62 6c 61 63 6b 2c 0d  |example, black,.|
000007f0  62 6c 75 65 2c 20 63 79  61 6e 20 61 6e 64 20 77  |blue, cyan and w|
00000800  68 69 74 65 2c 20 61 6e  64 20 63 72 65 61 74 65  |hite, and create|
00000810  20 61 20 70 69 63 74 75  72 65 20 77 68 69 63 68  | a picture which|
00000820  20 6c 6f 6f 6b 73 20 67  6f 6f 64 20 69 6e 20 74  | looks good in t|
00000830  68 69 73 20 63 6f 6c 6f  75 72 0d 73 63 68 65 6d  |his colour.schem|
00000840  65 2c 20 79 6f 75 20 6d  75 73 74 20 72 65 6d 65  |e, you must reme|
00000850  6d 62 65 72 20 74 68 61  74 20 75 6e 6c 65 73 73  |mber that unless|
00000860  20 79 6f 75 20 64 65 66  69 6e 65 20 74 68 65 20  | you define the |
00000870  70 61 6c 65 74 74 65 20  74 6f 20 74 68 65 73 65  |palette to these|
00000880  20 66 6f 75 72 0d 63 6f  6c 6f 75 72 73 20 62 65  | four.colours be|
00000890  66 6f 72 65 20 70 65 72  66 6f 72 6d 69 6e 67 20  |fore performing |
000008a0  2a 4c 4f 41 44 20 74 6f  20 72 65 73 74 6f 72 65  |*LOAD to restore|
000008b0  20 74 68 65 20 70 69 63  74 75 72 65 2c 20 69 74  | the picture, it|
000008c0  20 6d 61 79 20 61 70 70  65 61 72 0d 72 61 74 68  | may appear.rath|
000008d0  65 72 20 6f 64 64 20 77  68 65 6e 20 72 65 6c 6f  |er odd when relo|
000008e0  61 64 65 64 2c 20 61 73  20 69 74 20 77 69 6c 6c  |aded, as it will|
000008f0  20 61 70 70 65 61 72 20  69 6e 20 62 6c 61 63 6b  | appear in black|
00000900  2c 20 72 65 64 2c 20 79  65 6c 6c 6f 77 20 61 6e  |, red, yellow an|
00000910  64 0d 77 68 69 74 65 20  2d 20 74 68 65 20 64 65  |d.white - the de|
00000920  66 61 75 6c 74 20 63 6f  6c 6f 75 72 20 73 63 68  |fault colour sch|
00000930  65 6d 65 2e 0d 0d 2d 20  54 68 65 20 65 78 61 63  |eme...- The exac|
00000940  74 20 72 65 61 73 6f 6e  20 77 68 79 20 74 68 69  |t reason why thi|
00000950  73 20 68 61 70 70 65 6e  73 20 69 73 20 72 61 74  |s happens is rat|
00000960  68 65 72 20 63 6f 6d 70  6c 69 63 61 74 65 64 2c  |her complicated,|
00000970  20 62 75 74 20 69 66 20  79 6f 75 0d 61 6c 6c 6f  | but if you.allo|
00000980  77 20 74 68 65 20 63 75  72 73 6f 72 20 74 6f 20  |w the cursor to |
00000990  67 6f 20 64 6f 77 6e 20  6f 66 66 20 74 68 65 20  |go down off the |
000009a0  62 6f 74 74 6f 6d 20 6c  69 6e 65 20 6f 66 20 74  |bottom line of t|
000009b0  68 65 20 73 63 72 65 65  6e 2c 20 61 6e 64 20 61  |he screen, and a|
000009c0  6c 6c 6f 77 0d 74 68 65  20 73 63 72 65 65 6e 20  |llow.the screen |
000009d0  74 6f 20 73 63 72 6f 6c  6c 20 75 70 20 6f 6e 65  |to scroll up one|
000009e0  20 6c 69 6e 65 2c 20 74  68 69 73 20 74 65 63 68  | line, this tech|
000009f0  6e 69 71 75 65 20 73 74  6f 70 73 20 77 6f 72 6b  |nique stops work|
00000a00  69 6e 67 20 75 6e 74 69  6c 20 79 6f 75 0d 70 65  |ing until you.pe|
00000a10  72 66 6f 72 6d 20 61 20  4d 4f 44 45 20 63 6f 6d  |rform a MODE com|
00000a20  6d 61 6e 64 2c 20 6f 72  20 63 6c 65 61 72 20 74  |mand, or clear t|
00000a30  68 65 20 73 63 72 65 65  6e 20 75 73 69 6e 67 20  |he screen using |
00000a40  43 4c 53 2e 20 42 61 73  69 63 61 6c 6c 79 20 77  |CLS. Basically w|
00000a50  68 61 74 0d 68 61 70 70  65 6e 73 20 69 73 20 74  |hat.happens is t|
00000a60  68 61 74 20 74 68 65 20  63 6f 6d 70 75 74 65 72  |hat the computer|
00000a70  20 64 6f 65 73 20 6e 6f  74 20 70 68 79 73 69 63  | does not physic|
00000a80  61 6c 6c 79 20 6d 6f 76  65 20 65 76 65 72 79 20  |ally move every |
00000a90  6c 69 6e 65 20 6f 66 20  74 65 78 74 0d 6f 6e 20  |line of text.on |
00000aa0  74 68 65 20 73 63 72 65  65 6e 20 75 70 20 6f 6e  |the screen up on|
00000ab0  65 20 6c 69 6e 65 2c 20  62 75 74 20 69 6e 73 74  |e line, but inst|
00000ac0  65 61 64 20 6d 61 6b 65  73 20 61 20 6e 6f 74 65  |ead makes a note|
00000ad0  20 74 68 61 74 20 65 76  65 72 79 20 6c 69 6e 65  | that every line|
00000ae0  20 69 6e 0d 73 63 72 65  65 6e 20 6d 65 6d 6f 72  | in.screen memor|
00000af0  79 20 69 73 20 73 74 6f  72 65 64 20 6f 6e 65 20  |y is stored one |
00000b00  6c 69 6e 65 20 6c 6f 77  65 72 20 74 68 61 6e 20  |line lower than |
00000b10  69 74 20 73 68 6f 75 6c  64 20 62 65 2e 20 57 68  |it should be. Wh|
00000b20  65 6e 20 79 6f 75 20 72  65 6c 6f 61 64 0d 66 72  |en you reload.fr|
00000b30  6f 6d 20 64 69 73 6b 2c  20 74 68 69 73 20 6e 6f  |om disk, this no|
00000b40  74 65 20 69 73 20 6c 6f  73 74 2c 20 61 6e 64 20  |te is lost, and |
00000b50  74 68 65 20 63 6f 6d 70  75 74 65 72 20 64 72 61  |the computer dra|
00000b60  77 73 20 65 76 65 72 79  20 6c 69 6e 65 20 6c 6f  |ws every line lo|
00000b70  77 65 72 20 74 68 61 6e  0d 69 74 20 73 68 6f 75  |wer than.it shou|
00000b80  6c 64 20 62 65 2e 20 45  61 63 68 20 74 69 6d 65  |ld be. Each time|
00000b90  20 74 68 61 74 20 43 4c  53 20 6f 72 20 4d 4f 44  | that CLS or MOD|
00000ba0  45 20 69 73 20 65 78 65  63 75 74 65 64 2c 20 73  |E is executed, s|
00000bb0  63 72 65 65 6e 20 6d 65  6d 6f 72 79 20 69 73 0d  |creen memory is.|
00000bc0  63 6c 65 61 72 65 64 20  61 6e 64 20 72 65 69 6e  |cleared and rein|
00000bd0  69 74 69 61 74 65 64 2c  20 73 6f 20 74 68 61 74  |itiated, so that|
00000be0  20 65 76 65 72 79 20 6c  69 6e 65 20 69 73 20 73  | every line is s|
00000bf0  74 6f 72 65 64 20 69 6e  20 6d 65 6d 6f 72 79 20  |tored in memory |
00000c00  77 68 65 72 65 20 79 6f  75 0d 77 6f 75 6c 64 20  |where you.would |
00000c10  65 78 70 65 63 74 20 69  74 20 74 6f 20 62 65 2e  |expect it to be.|
00000c20  20 53 69 6d 70 6c 79 20  72 65 6d 65 6d 62 65 72  | Simply remember|
00000c30  20 6e 6f 74 20 74 6f 20  61 6c 6c 6f 77 20 74 68  | not to allow th|
00000c40  65 20 73 63 72 65 65 6e  20 74 6f 20 73 63 72 6f  |e screen to scro|
00000c50  6c 6c 0d 62 65 74 77 65  65 6e 20 63 6c 65 61 72  |ll.between clear|
00000c60  69 6e 67 20 69 74 2c 20  61 6e 64 20 73 61 76 69  |ing it, and savi|
00000c70  6e 67 20 74 68 65 20 63  6f 6e 74 65 6e 74 73 20  |ng the contents |
00000c80  6f 66 20 73 63 72 65 65  6e 20 6d 65 6d 6f 72 79  |of screen memory|
00000c90  20 74 6f 20 64 69 73 63  2e 0d 0d 2d 20 54 68 65  | to disc...- The|
00000ca0  20 66 69 6c 65 73 20 63  72 65 61 74 65 64 20 77  | files created w|
00000cb0  68 65 6e 20 79 6f 75 20  73 61 76 65 20 74 68 65  |hen you save the|
00000cc0  20 63 6f 6e 74 65 6e 74  73 20 6f 66 20 73 63 72  | contents of scr|
00000cd0  65 65 6e 20 6d 65 6d 6f  72 79 20 74 6f 20 64 69  |een memory to di|
00000ce0  73 6b 0d 61 72 65 20 66  61 69 72 6c 79 20 6c 61  |sk.are fairly la|
00000cf0  72 67 65 20 2d 20 73 6f  20 6c 61 72 67 65 2c 20  |rge - so large, |
00000d00  69 6e 20 66 61 63 74 2c  20 74 68 61 74 20 79 6f  |in fact, that yo|
00000d10  75 20 63 61 6e 20 6f 66  74 65 6e 20 6f 6e 6c 79  |u can often only|
00000d20  20 66 69 74 20 61 72 6f  75 6e 64 0d 31 35 20 73  | fit around.15 s|
00000d30  75 63 68 20 66 69 6c 65  73 20 6f 6e 74 6f 20 65  |uch files onto e|
00000d40  61 63 68 20 64 69 73 6b  20 74 68 61 74 20 79 6f  |ach disk that yo|
00000d50  75 20 75 73 65 20 28 74  68 65 20 65 78 61 63 74  |u use (the exact|
00000d60  20 6e 75 6d 62 65 72 20  64 65 70 65 6e 64 73 20  | number depends |
00000d70  75 70 6f 6e 0d 77 68 61  74 20 6d 6f 64 65 73 20  |upon.what modes |
00000d80  74 68 65 20 69 6d 61 67  65 73 20 61 72 65 20 69  |the images are i|
00000d90  6e 29 2e 20 54 68 65 72  65 66 6f 72 65 20 74 68  |n). Therefore th|
00000da0  69 73 20 74 65 63 68 6e  69 71 75 65 20 69 73 20  |is technique is |
00000db0  6e 6f 74 20 66 65 61 73  61 62 6c 65 0d 66 6f 72  |not feasable.for|
00000dc0  20 61 20 6c 61 72 67 65  20 6e 75 6d 62 65 72 20  | a large number |
00000dd0  6f 66 20 69 6d 61 67 65  73 2e 20 45 61 63 68 20  |of images. Each |
00000de0  73 63 72 65 65 6e 20 69  6e 20 61 20 67 61 6d 65  |screen in a game|
00000df0  20 6c 69 6b 65 20 53 68  69 70 77 72 65 63 6b 65  | like Shipwrecke|
00000e00  64 20 63 61 6e 6e 6f 74  0d 62 65 20 73 74 6f 72  |d cannot.be stor|
00000e10  65 64 20 69 6e 20 74 68  69 73 20 77 61 79 20 2d  |ed in this way -|
00000e20  20 69 66 20 49 20 68 61  64 20 73 74 6f 72 65 64  | if I had stored|
00000e30  20 65 76 65 72 79 20 73  63 72 65 65 6e 20 6f 66  | every screen of|
00000e40  20 74 68 65 20 67 61 6d  65 20 6c 69 6b 65 20 74  | the game like t|
00000e50  68 69 73 2c 0d 69 74 20  77 6f 75 6c 64 20 68 61  |his,.it would ha|
00000e60  76 65 20 72 65 71 75 69  72 65 64 20 73 69 78 20  |ve required six |
00000e70  66 6c 6f 70 70 79 20 64  69 73 6b 73 20 74 6f 20  |floppy disks to |
00000e80  73 74 6f 72 65 20 74 68  65 20 64 61 74 61 20 66  |store the data f|
00000e90  6f 72 20 74 68 65 20 67  61 6d 65 21 0d 54 68 69  |or the game!.Thi|
00000ea0  73 20 6d 65 61 6e 73 20  74 68 61 74 20 73 61 76  |s means that sav|
00000eb0  65 64 20 73 63 72 65 65  6e 73 20 6d 75 73 74 20  |ed screens must |
00000ec0  62 65 20 72 65 73 65 72  76 65 64 20 66 6f 72 20  |be reserved for |
00000ed0  74 68 65 20 70 75 72 70  6f 73 65 73 20 6f 66 20  |the purposes of |
00000ee0  74 69 74 6c 65 0d 73 63  72 65 65 6e 73 20 6f 6e  |title.screens on|
00000ef0  6c 79 2e 0d 0d                                    |ly...|
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