Epple-II/doc/screenshots.asciidoc

== Screenshots



=== DOS 3.3 System Master boot

image::dos330boot.png[]

Here we've configured an Apple ][ plus, with a disk
controller in slot 6, and a language card in slot 0.
We've booted the DOS 3.3 System Master disk. It correctly
identifies the machine as an Apple ][ plus, and then
loads Integer BASIC into the language card. You can switch
between Applesoft and Integer BASIC by using the +FP+ and
+INT+ commands.



=== DOS 3.1 System Master on Revision 0 motherboard

image::dos310rev0.png[]

Here we've configured an Apple ][ (Integer BASIC ROMs),
with a Revision Zero motherboard, and a disk
controller (with 13-sector ROMs) in slot 6. With a
revision 0 motherboard, when the machine is powered-on,
the CPU doesn't start actually running until you
manually press the RESET button. Also, the old Monitor
ROMs do not boot from the disk drives automatically;
you need to type +C600G+ to boot.
We've booted the DOS 3.1 System Master disk and done a
catalog of it. As you can see, with a revision 0 motherboard,
the text is displayed in green and purple, which are also the
only two HIRES colors. Later revisions
of the motherboard added a ``color burst killer'' which is
active during text mode, so the text would be strictly white.
Two more HIRES colors, blue and orange, were also added in
later revisions.



=== PRODOS 1.1.1 boot

image::prodos.png[]

Here we've configured an Apple ][ plus with language card
and disk drive. We're booting a PRODOS 1.1.1 disk.



=== Bishop's Apple Split

image::applesplit.png[]

The October 1982 issue of http://en.wikipedia.org/wiki/Softalk[Softalk]
featured an article by Bob Bishop entitled
http://rich12345.tripod.com/aiivideo/softalk.html[Have an Apple Split], which describes
in some detail the inner workings of the Apple ]['s video processing. Listings 1 and 2 from that
article show a short Applesoft program and assembly language subroutine that allow the Apple ][
to have a screen split between text and graphics display. To achieve this on the EPPLE ][,
copy the following text and paste it into the emulator (at the Applesoft +]+ prompt). Since the
EPPLE ][ accurately emulates the video scanning and timing of the original Apple ][s, this
``split screen'' technique works successfully.
The rest of the behavior described in the article (the floating data bus) is also emulated
faithfully by the EPPLE ][.

[source,vbs]
---------------------------------
CALL -151

300:8D 52 C0 A9 E0 A2 04 CD 51 C0 D0 F9 CA D0 F8 A9
310:A0 A2 04 CD 50 C0 D0 F9 CA D0 F8 8D 51 C0 60

E000G

100 HOME

200 FOR K = 0 TO 39
210   POKE 1448+K, 14*16
220   POKE 2000+K, 10*16
230   COLOR = K+4
240   VLIN 24, 45 AT K
250 NEXT K

300 VTAB 6 : HTAB 17
310 PRINT "APPLE II"

400 CALL 768
500 GOTO 400

RUN
---------------------------------



=== Mysterious Pink Line

image::pinkmystery.png[]

Jim Sather's book 
http://www.scribd.com/doc/201423/Understanding-the-Apple-II-by-Jim-Sather-1983Quality-Software[Understanding the Apple II],
which was the primary
reference for the internal design of the EPPLE ][ emulator, describes the video
generation process of the Apple ][, in great detail, in Chapter 8.
On page 8-21 he shows a simple Applesoft BASIC program (shown below)
that shows an example of one of the hi-res idiosyncrasies on the Apple ][.
The program would logically draw three orange lines, but due to the
video cutoff and extension of half-dot shifted pixels, instead the right
line is brown, and there is a ``mysterious pink line'' (actually magenta)
on the far left of the screen. The EPPLE ][ faithfully emulates this behavior.

[source,vbs]
---------------------------------
NEW

10 HGR : HCOLOR = 5 : HPLOT 5,159 TO 5,0 TO 279,0 TO 279,159

RUN
---------------------------------



=== Split Screen HIRES/LORES colors

image::splitcolors.png[]

Jim Sather's book 
http://www.scribd.com/doc/201423/Understanding-the-Apple-II-by-Jim-Sather-1983Quality-Software[Understanding the Apple II],
shows an Applesoft BASIC
program and assembly language subroutine on pages 3-16 and 3-17 (reproduced
below) that produce the display shown here. The screen is split between HIRES
and LORES graphics by a timed loop that manipulates the screen switches.
(Press any key repeatedly to move the position of the split.)

Notice that the Apple ][ can actually produce more HIRES colors than are
documented in the standard Apple reference manuals. White, black, green,
purple, blue, and orange are normally documented, but by careful manipulation
of the high-bit (half-dot shift indicator) of the HIRES display byte, many
other colors can be produced. The additional colors match some LORES colors.
Also notice that the text at the bottom of the screen is colored green and
purple while in mixed text/graphics mode. This is because the ``color
burst killer'' circuit is not active while displaying graphics on the
Apple ][ machines.

[source,vbs]
---------------------------------
CALL -151
1F00:AC 54 C0 A0 27 20 27 1F
1F08:AC 10 C0 AC 00 C0 30 F3
1F10:69 01 29 01 AA BC 56 C0
1F18:A2 08 20 31 1F A0 31 20
1F20:27 1F 18 90 E6 D0 01 88
1F28:88 EA D0 F9 60 48 68 EA
1F30:EA A0 62 20 27 1F EA CA
1F38:D0 F3 60

E000G
 30 HGR : HOME : VTAB 21 : PRINT "1  7  D  2  8  E  B  4  5  A 3 6 C 9 F 8"
 40 DIM COLR(39), X(21)
100 FOR A = 0 TO 39 : READ COLR(A) : COLOR = COLR(A) : VLIN 0, 39 AT A : NEXT A
200 FOR A = 0 TO 21 : READ COLR(A) : READ X(A) : HCOLOR = COLR(A)
210 HPLOT X(A), 0 TO X(A), 159 : NEXT A
220 FOR A = 8319 TO 16383 STEP 128 : POKE A, 64 : NEXT A
300 CALL 7936
400 REM  LORES DATA
410 DATA 1,0,7,7,0,13,13,0,2,2,0,8,8,0,14,14,0,11,11,0
420 DATA 4,4,0,0,5,0,0,10,0,3,0,6,0,12,0,9,0,15,0,8
500 REM  HIRES DATA
510 DATA 4,0,3,20,4,21,3,41,4,42,7,62,7,83,7,104,3,105,7,125,3,126,7,159,3,161
520 DATA 7,180,3,182,3,206,7,220,3,233,7,247,3,262,3,263,7,279

RUN
---------------------------------