[PageStream 2 document STEPCH1.DOC: 8.50 x 11.00 in, 2 objects, facing pages] --- Page 1 --- SECTION ONE INTRODUCTION 1.0 Overview The STe+ is an enhancement of the Atari STe series of 68000-based computers. It is upwardly compatible with the Atari STe and includes a number of new features, including a DOS compatible hardware AT emulator using an 80286 microprocessor, an internal hard drive, and high density 3.5" floppy diskette. The STe+ is designed as an integrated unit with keyboard, processor, memory, and I/O control in one package. The STe+ has 2 or 4 megabytes (2,097,136 or 4,194,272 bytes ) of RAM. The STe+ also comes with a modulator for TV output and power supply integrated into the case. 1.1 System Features Motorola MC68000 microprocessor running at 8MHz 80286 microprocessor providing a DOS-compatible AT equivalent system interface. 2 socketed ROMs, providing 256K of ROM space 2 to 4 MBytes of system RAM Atari ACSI DMA channel (for Atari Hard Disk, Laser Printer, CD-ROM, etc) One low speed asynchronous serial I/O port using a 68901 MFP Parallel I/O Port, implemented using one of the parallel ports on the sound chip ST compatible intelligent keyboard with mouse Internal video modes that are compatible with those in the Atari ST series Musical subsystem with Programmable Sound Generator, DMA Sound and Musical Instrument Digital Interface (MIDI) 3.5" Floppy Disk Controller and interface providing 360KB, 720KB and 1.44MB densities sharing the ACSI DMA channel 2.5" IDE Hard Drive and interface providing 20MB and 30MB densities. 1.2 Case Design The STe and STe+ are nearly identical. The upper case has openings for the keyboard and a lens for both the power indicator LED (front left corner) and the Disk Drive Activity LED (mid right side). (see Fig. 1) 1.2.1 STe+ Upper Case 1.2.2 STe+ Left Side Panel The left side panels of both machines have slots for the expansion cartridge, two MIDI ports. (see Fig. 2) Figure 1-2 The right side panel has a slot for the floppy disk drive. (see Fig. 1-3) STe+ Right Side Panel Figure 1-4 The STe+ back panel contains (left to right) the modem (RS-232) connector, printer connector, hard disk/DMA connector, external floppy disk connector, television output, --- Page 2 --- monitor connector, power switch, stereo output (right and left), AC power input, and reset button. (see Fig. 1-4) STe+ Back Panel Figure 1-5 1.3 Power Supply The STe+ has an integral switching power supply providing +5V and +12V. There is a 2A fuse. Voltage should be adjusted to 5.1V. The power supply has overcurrent protection; if the fuse is blown, a catastrophic failure is likely, such as shorted primary. 1.3.1 Power Supply Rating Current out:4.0A at +5V, 0.9A at +12V Max. power in:30.8W Typical (in system) Demand: Typical current:1.75A at 5V, 86 mA at +12V Max. current:2.2A at +5V, 90 mA at +12 (during disk access) 1.4 Negative Supplies The STe+ motherboard contains two small switching voltage regulators (the TL497 or equivalent) that are used to provide additional voltages. U204 is used to generate the positive and negative voltages for the RS232C line drivers. These voltages are normally 12 VDC. U205 is used to generate a -5 VDC supply for the audio subsection. This output is heavily filtered to reduce the switching noise that might otherwise appear in the audio output.