Atari 1040STE, Руководство по обслуживанию на месте

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until a read is performed. Similarly, they will not be driven after a read until a write is
performed.
2.12.8.2 PADDLES
One pair of paddles can be plugged into Joystick 0 (Paddle 0). A second set can be
plugged into Joystick 1 (Paddle 1). The current position of each of the four paddles is
reported at these locations. The fire buttons are the same as for the respective
joystick. The triggers for the paddles are read as bits one and two of FF9202 (JOY0
Left and Right).
2.12.8.3 LIGHT GUN/PEN
A light gun or pen can be plugged into Joystick 0. The current position that the gun
or pen is pointing to is reported by these registers. The position is accurate to within
(X direction only):
4 Pixels in 320 x 200 Mode 8 Pixels in 640 x 200 Mode 16 Pixels in 640 x 400 Mode
Accurate to 1 pixel in the Y direction in all modes. Accuracies do not account for the
quality of the light gun or pen. Note that the X position is given in pixels for 320 x 200
only. In order to get correct results in 640 x 200 mode this number needs to be
shifted left
one bit and in 640 x 400 modes this number needs to be shifted left two bits.
2.13 SYSTEM STARTUP
After a RESET (power–up or reset button) the 68000 will start executing at the
address pointed to by locations 4–7, which is ROM (GSTMCU maps the first 8 bytes
of ROM at E00000 into the addresses 0–7). Location 000004 points to the start of
the operating system code in ROM. The following sequence is then executed:
1. Perform a reset instruction (outputs a reset pulse). (RESET.)
2. Read the longword at cartridge address FA0000. If the data read is a "magic
number", execute from the cartridge (cartridge takes over here). If not,
continue.
3. Check for a warm start (see if RAM locations are valid). If not, initialize the
memory controller.
4. Initialize the PSG chip, deselect disk drives.
5. Initialize color palettes and set screen address.
6. If not a warm start, zero memory.
7. Set up operating system variables in RAM.
8. Set up exception vectors.
9. Initialize MFP.
10.
Set screen resolution.
11. Attempt to boot floppy; attempt to boot hard disk; run program if successful.
12. If no boot disk, load the desktop ROM on board 256K ROM.