Atari 1040STE, Field Service Manual

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SECTION TWO: THEORY OF OPERATION
2.0 OVERVIEW
The 520STE and 1040STE share a common architecture, using the same LSI chip
set. The most significant difference is the addition (to the 1040STE) of one bank of
512K of RAM, for a total of 1024K (1,048,568 bytes). Except for the additional RAM,
the differences between the 520STE and 1040STE are transparent to software. The
hardware can be considered as consisting of a main system (central processing unit
and support chips) and several Input/Output subsystems
.
2.1 MAIN SYSTEM
•
MC68000 running at 8 MHz
•
256 kbyte ROM
•
512/1024 kbyte RAM
•
Direct Memory Access Support
•
System Timing and Bus Control
•
Interrupt Control
2.2 AUDIO/VIDEO SUBSYSTEM
The STE has bit–mapped video display, normally using 32,000 bytes of RAM,
relocatable anywhere in memory. There are three display modes available:
RGB, with the ability to be GenLocked:
1. 320 x 200 pixel, 16 color palette from 4096 selections
2. 640 x 200 pixel, 4 color palette from 4096 selections
Monochrome:
3. 640 x 400 pixel, monochrome monitor interface
2.2.1 Audio Output
The STE has a programmable sound chip and 8–bit stereo DMA at 4 playback
frequencies.
2.2.2 Television Interface
NTSC, PAL I and PAL B.