400 800 XL XE

 1.14) What issues surround NTSC vs PAL versions of the 8-bit Atari?

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Contributors to this section:
Wayne Booth, Graham Thornton, Brent Buescher Jr., Thomas Richter, Jindroush,
Sc0rpi0.  Thanks especially to Piotr Fusik for his extensive help with this
section.

Some quick definitions first:

NTSC: "National Television Standards Committee"
TV signal standard used in North America, Central America, a number of South
American countries, and some Asian countries, including Japan.
  o  525 lines per frame
  o  60 half-frames per second (interlaced) = 60 Hz
  o  Complete frame refreshed 30 times per second

PAL: "Phase Alternation by Line"
TV signal standard used in the United Kingdom, most of the rest of Europe,
several South American countries, some Middle East and Asian countries,
several African countries, Australia, New Zealand, and other Pacific island
countries.
  o  625 lines per frame
  o  50 half-frames per second (interlaced) = 50 Hz
  o  Complete frame refreshed 25 times per second.

SECAM: "Sequentiel couleur avec memoire"
TV signal standard still used in France, the former USSR, and some African
countries.  Until the 1980&#146s SECAM was the standard in eastern Europe,
including East Germany, Poland, Czech Republic, Slovakia, and Hungary.
  o  625 lines per frame
  o  50 half-frames per second (interlaced) = 50 Hz
  o  Complete frame refreshed 25 times per second.


In some ways the specifications of the hardware in the 8-bit Atari computer
are closely linked to the specifications of the television signal standard
used in the market where the machine is designed to be used.  Thus there were
generally two versions of each 8-bit Atari computer model produced: one for
NTSC markets, containing NTSC versions of the ANTIC and GTIA chips, and one
for PAL markets, containing PAL versions of the ANTIC and GTIA chips.

As for SECAM versions, Piotr Fusik writes (3/06):
   To my knowledge, Atari had only plans or prototypes of SECAM
   machines.  In Poland we had PAL Ataris, which was a problem at the times
   of SECAM.  You could connect a PAL Atari to a SECAM TV, but there was
   no color and (IIRC) no sound.  The solution was to buy an inexpensive
   converter mounted inside the TV, so the TV supported PAL in addition
   to SECAM.  This was quite popular, because the VCRs were PAL, too.


Now then, what might happen if you run a software program designed with an
NTSC Atari on a PAL Atari, or a program designed with a PAL Atari on an NTSC
Atari?  There are a number of possibilities:

1) The program may run faster or slower than intended.

All hardware timing is slightly different between NTSC and PAL machines, so
most programs run slightly faster on NTSC, slightly slower on PAL.  This can
be significant in applications that are computation- or timing-sensitive, such
as music players, or in any programs designed to simulate real time.

2) The program may exhibit some sort of "screen flickering" effect, or the
   system may completely hang.

The NTSC versions of the ANTIC chip generate a video signal with a screen
refresh rate of about 60Hz, whereas the PAL versions of the ANTIC chip
generate a video signal with a screen refresh rate of about 50Hz.  The slower
refresh frequency of PAL machines translates into more available computation
time per screen frame.  Computation-intensive software written for PAL
machines that assumes more available time per screen frame than is available
on NTSC machines will not run correctly on NTSC machines.

3) The colors displayed by the program are not what was intended.

The following two paragraphs are compiled from postings by Thomas Richter:

   While NTSC machines contain a single system clock crystal oscillator, in
   PAL machines a second oscillator that runs at 5/4 of the main system clock
   frequency is present to generate the color frequencies needed to drive
   GTIA.

   This factor of 5/4 is the reason why you don&#146t get the popular "artifacted
   colors"/"pseudo-colors" (or, at least, not very good ones) in the ANTIC-F
   (Graphics 8) mode when displayed with a PAL Atari.

As a result, programs that are written with assumptions about color
artifacting effects, which vary depending upon the color CRT display device
used, will also vary in appearance depending upon whether the machine is NTSC
or PAL.

Also, the actual palettes of colors that can be generated by the computer
look somewhat different depending upon whether the machine is NTSC or PAL.

4) The program may explicitly refuse to run on incorrect hardware.

Software (some demos) may be designed to determine whether the Atari is NTSC
or PAL, and refuse to run if the hardware present does not match what is
expected.

Typically, NTSC/PAL is determined by checking the "PAL" memory register
provided by the OS, which is based on the version of GTIA that is present:

   Memory location 53268 ($D014, "PAL") indicates whether the system contains
   an NTSC or a PAL GTIA.  In Atari BASIC, PEEK(53268) returns 15 if an NTSC
   GTIA is present, or 1 if a PAL GTIA is present.

Alternatively, software may determine NTSC/PAL by determining how many
scanlines are being generated by ANTIC.  The NTSC ANTIC generates 262
scanlines, while the PAL ANTIC generates 312 scanlines.  This technique is
utilized by the "Numen" demo by Taquart, which refuses to run on an NTSC
ANTIC.

5) The program may not load correctly at all.

This would mostly likely result from copy protection techniques based upon
precise hardware timing associated with disk drives, cassette recorders, or
components of the computer itself, where the timing was not anticipated to
vary depending upon NTSC vs. PAL hardware.

According to Jindroush (2/26/02), two examples of programs that run on NTSC
machines but not PAL machines as a result of timing-based copy protection
techniques (probably based on vblank timing) are Transylvania and The Quest
by Penguin Software.

6) The program may run fine on both NTSC and PAL machines.

Either the differences are too slight to matter, or the software may be
sophisticated enough to detect NTSC vs PAL hardware, as described above, and
act accordingly.

An examples of a program that alters its behavior depending upon detection of
NTSC versus PAL is Ghostbusters by Activision (checks for NTSC/PAL GTIA).


Bottom line:
============
Software written for NTSC machines (North America) will (almost) always work
on PAL machines (Europe), but software designed on PAL machines won&#146t
necessarily work on NTSC machines.

Replacing the NTSC ANTIC chip in an NTSC Atari with a PAL ANTIC changes the
screen refresh rate to 50Hz, allowing most of the PAL-only European software
to run on a North American NTSC Atari.  However, make sure your display device
can support a 50Hz PAL signal first!  North American Atari users can also
obtain and use real European PAL Atari machines, with the same caveat
concerning the display device.

------------------------------

Subject: 1.15) What are the pinouts for the various ports on the Atari?

Contributors to this section: Steve Wallance (CX22 trackball meanings),
Jer Sobola (SECAM monitor port)

Controller Port (4 on 400/800, 2 on all others):
      1         5
       o o o o o
        o o o o
       6       9                      CX22 trackball meanings:
1. (Joystick) Forward Input               X Direction
2. (Joystick) Back Input                  X Motion
3. (Joystick) Left Input                  Y Direction
4. (Joystick) Right Input                 Y Motion
5. B Potentiometer Input
6. Trigger Input/Light Pen Input (400 supports the Light Pen in port 4 only)
7. +5V
8. Ground
9. A Potentiometer Input

Serial I/O (SIO) Port (all machines):
         2           12
          o o o o o o
         o o o o o o o
        1             13
1. Clock Input             8. Motor Control
2. Clock Output            9. ~Proceed
3. Data Input             10. +5V/Ready (not on 1200XL)
4. Ground                 11. Audio Input
5. Data Output            12. +12V (400/800 only. 1400XL/1450XLD?)
6. Ground                 13. ~Interrupt
7. ~Command

Monitor Port (all but 400, N. American 600XL, XE game system, SECAM systems):
3 o     o 1
   o   o
5   o   4
     2
1. Composite Luminance (Composite Video on 600XL)
2. Ground
3. Audio Output
4. Composite Video
5. Composite Chroma (not on 800XL(most),1200XL; Ground on 600XL)

Monitor Port, SECAM systems:
  5    V    1    1. +12V DC 5mA max
    o     o      2. Audio 1 output
       o 3       3. Audio 2 output (amplitude is about 6 times Audio 1)
    o     o      4. Video output
  4    o    2    5. GND
       6         6. +5V 100mA max

Power (all but 400,800,1200XL,1400XL,1450XLD):
    7     6        1. +5V
     o   o         2. Shield
  3 o     o 1      3. Ground
     o   o         4. +5V
   5   o   4       5. Ground
       2           6. +5V
                   7. Ground

Cartridge Slot (present on all machines; Left Cartridge Slot on 800):
     A  B  C  D  E  F  H  J  K  L  M  N  P  R  S
     o  o  o  o  o  o  o  o  o  o  o  o  o  o  o
     o  o  o  o  o  o  o  o  o  o  o  o  o  o  o
     1                                         15
1. ~S4 Chip Select--$8000 to $9FFF  A. RD4 ROM present--$8000 to $9FFF
2. A3 CPU Address bus line          B. GND Ground
3. A2 CPU Address bus line          C. A4 CPU Address bus line
4. A1 CPU Address bus line          D. A5 CPU Address bus line
5. A0 CPU Address bus line          E. A6 CPU Address bus line
6. D4 CPU Data bus line             F. A7 CPU Address bus line
7. D5 CPU Data bus line             H. A8 CPU Address bus line
8. D2 CPU Data bus line             J. A9 CPU Address bus line
9. D1 CPU Data bus line             K. A12 CPU Address bus line
10. D0 CPU Data bus line             L. D3 CPU Data bus line
11. D6 CPU Data bus line             M. D7 CPU Data bus line
12. ~S5 Chip Select--$A000 to $BFFF  N. A11 CPU Address bus line
13. +5V                              P. A10 CPU Address bus line
14. RD5 ROM present--$A000 to $BFFF  R. R/~W CPU read/write
15. ~CCTL Cartridge control select   S. B02,Phi2 CPU Phase 2 clock

Right Cartridge Slot (800 only):
     A  B  C  D  E  F  H  J  K  L  M  N  P  R  S
     o  o  o  o  o  o  o  o  o  o  o  o  o  o  o
     o  o  o  o  o  o  o  o  o  o  o  o  o  o  o
     1                                         15
1. R/~W CPU read/write late         A. B02,Phi2 CPU Phase 2 clock
2. A3 CPU Address bus line          B. GND Ground
3. A2 CPU Address bus line          C. A4 CPU Address bus line
4. A1 CPU Address bus line          D. A5 CPU Address bus line
5. A0 CPU Address bus line          E. A6 CPU Address bus line
6. D4 CPU Data bus line             F. A7 CPU Address bus line
7. D5 CPU Data bus line             H. A8 CPU Address bus line
8. D2 CPU Data bus line             J. A9 CPU Address bus line
9. D1 CPU Data bus line             K. A12 CPU Address bus line
10. D0 CPU Data bus line             L. D3 CPU Data bus line
11. D6 CPU Data bus line             M. D7 CPU Data bus line
12. ~S4 Chip Select--$8000 to $9FFF  N. A11 CPU Address bus line
13. +5V                              P. A10 CPU Address bus line
14. RD4 ROM present--$8000 to $9FFF  R. R/~W Read/write
15. ~CCTL Cartridge control select   S. B02,Phi2 CPU Phase 2 clock

Parallel Bus Interface (PBI) (600XL and 800XL only):
1                                                                       49
o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o
o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o
2                                                                       50
  1. GND Ground                    2. ~EXTSEL External Select
  3. A0 CPU Address bus line       4. A1 CPU Address bus line
  5. A2 CPU Address bus line       6. A3 CPU Address bus line
  7. A4 CPU Address bus line       8. A5 CPU Address bus line
  9. A6 CPU Address bus line      10. GND Ground
11. A7 CPU Address bus line      12. A8 CPU Address bus line
13. A9 CPU Address bus line      14. A10 CPU Address bus line
15. A11 CPU Address bus line     16. A12 CPU Address bus line
17. A13 CPU Address bus line     18. A14 CPU Address bus line
19. GND Ground                   20. A15 CPU Address bus line
21. D0 CPU Data bus line         22. D1 CPU Data bus line
23. D2 CPU Data bus line         24. D3 CPU Data bus line
25. D4 CPU Data bus line         26. D5 CPU Data bus line
27. D6 CPU Data bus line         28. D7 CPU Data bus line
29. GND Ground                   30. GND Ground
31. B02,Phi2 CPU Phase 2 clock   32. GND Ground
33. NC Reserved                  34. ~RST Reset output
35. ~IRQ Interrupt request       36. ~RDY Ready input
37. NC Reserved                  38. ~EXTENB CPU External Enable
39. NC Reserved                  40. ~REF Refresh cycle
41. ~CAS Column Address Strobe   42. GND Ground
43. ~MPD Math Pack (FP) Disable  44. ~RAS Row Address Strobe
45. GND Ground                   46. LR/~W Latched read/write
47. 800XL: NC. 600XL: +5V        48. 800XL: NC. 600XL: +5V
49. Audio input                  50. GND Ground

Enhanced Cartridge Interface (ECI) (130XE, 800XE, and some 65XE only):
     A B C D E F H
     o o o o o o o
     o o o o o o o
     1           7
A. Reserved                  1. ~EXTSEL External Select
B. ~IRQ Interrupt request    2. ~RST Reset output
C. ~HALT Halt CPU            3. ~D1XX Chip select at area $D1xx
D. A13 CPU Address bus line  4. ~MPD Math Pack (FP) disable
E. A14 CPU Address bus line  5. Audio input
F. A15 CPU Address bus line  6. ~REF Refresh cycle
H. GND Ground                7. +5V

Keyboard Port (XE Game System only):
           1               8
            o o o o o o o o
             o o o o o o o
            9             15
1. KR2 Keyboard Response   8. K2 Keyboard Scan
2. K3 Keyboard Scan        9. Ground
3. K4 Keyboard Scan       10. Not Connected
4. K5 Keyboard Scan       11. Ground
5. KR1 Keybaord Response  12. Not Connected
6. K0 Keyboard Scan       13. Trigger 2
7. K1 Keyboard Scan       14. 5 VDC
                          15. 5 VDC

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