TENTATIVE SPECIFICATION ATARI 900XLA HOME COMPUTER *** DRAFT *** Page 2 SCOPE 09 Oct 84 1.0 SCOPE 1.1 General This specification describes the Atari model 900XLA Home Computer which contains a high quality audio sound synthesizer. This product shall be refered to as the 900XLA in the remainder of this specification. 2.0 REFERENCE DOCUMENTS The following documents form a part of this specification to the extent specified herein. Unless otherwise specified, the issue in effect on date of latest revision of this specification shall apply. 2.1 Uncontrolled Documents 2.2 Controlled Documents 2.2.1 C061618 Rev A Memory Management Unit Specification 2.2.2 C021859 Rev B AMY Sound Synthesis Circuit Specification 3.0 DESIGN GOALS 3.1 Comparison With Existing Product The Atari 900XLA with high quality audio differs from the Atari 900XL home computer in that it includes an AMY I sound synthesis integrated circuit, a 10-bit DAC, more extensive audio signal filtering and extra ROM space to accomodate driving programs and certain built-in sound programs. 3.2 Architecture 3.2.1 Functionality 3.2.1.1 General The 900XLA shall accept programs typed in the BASIC language on its keyboard or loaded from an attached cassette tape drive or diskette drive. It shall execute such programs in a manner compatible with the operation of the same programs on model 800XL computers except that additional features shall be supported to generate audio output. Audio capability shall include multivoice music generation, speech output and extensive sound effects including high quality emulation of naturally occuring sounds. ATARI 900XLA HOME COMPUTER *** DRAFT *** Page 3 DESIGN GOALS 09 Oct 84 3.2.2 Component Content The 900XLA shall include a moulded cabinet, a computer style keyboard, a power supply external to the cabinet, and a compliment of integrated circuits as follows: * SALLY variant of 6502 8-bit microprocessor * 8 64K by 1 bit dynamic RAMs * POKEY sound and input scanner * KERI video display circuits * 2 4051 bidirectional analog MUXes * 6520A pia * 555 timer * 74LS08 quad AND gate * 74LS139 dual 2 to 4 decoder * 20 pin PAL memory management unit * 32K byte ROM for system, BASIC and sound functions * 74LS74 dual D flip flop * AMY I sound synthesis circuit * 7533 10-bit CMOS digital to analog converter * LM324 quad single supply operational amplifier * OP22 low offset current operational amplifier 4.0 PERFORMANCE 4.1 Environmental 4.2 Endurance Levels 4.3 MTBF And MTTR 4.4 Compliances 4.5 Electrical Performance 4.5.1 Power Supply The power supply input is 100 to 132 volts at 55 to 65Hz. The output is 5.0 volts D.C plus or minus 2% with a maximum drain requirement of 1.75 amps. 4.5.2 SIO 4.5.3 Cartridges Cartridges to be inserted into the cartridge port of the 900XLA shall consume not more than 200 milliamperes over the entire tolerance range of the system power supply and environmental conditions. ATARI 900XLA HOME COMPUTER *** DRAFT *** Page 4 HARDWARE DESIGN 09 Oct 84 5.0 HARDWARE DESIGN 5.1 Packaging And Appearance 5.2 Electromechanical Subassemblies 5.2.1 Mechanical Details 5.2.2 Interface Specifications 5.2.3 Digital Hardware 5.2.3.1 SALLY 6502 CPU 5.2.3.2 ANTIC Display Processor IC 5.2.3.3 GTIA IC 5.2.3.4 PIA IC 5.2.3.5 POKEY IC 5.2.3.6 AMY I Sound Synthesis IC The AMY I sound synthesis IC used in the 900XLA is described in the specification C021859 Rev. B. A single such IC is used in the 900XLA to provide up to 8 musical voices or other sounds. The digital outputs of the AMY I IC are connected to the digital inputs of a digital to analog converter. The AMY I is used in a voice summing mode and no provision is made to utilize its individual voice mode. Monaural sound is provided. Conditioning of the DAC output signal is described with the audio summation circuit elsewhere in this specification. The clock to the AMY I IC is the system's 8 MHz clock. 5.2.3.7 Digital To Analog Converter IC The digital outputs of the AMY I IC are connected to the inputs of a model 7533 (Precision Monolithics Inc. or equivalent) digital to analog converter. This DAC provides 10 bits of resolution. 5.2.3.8 Memory Array ATARI 900XLA HOME COMPUTER *** DRAFT *** Page 5 HARDWARE DESIGN 09 Oct 84 5.2.3.8.1 Read/Write Memory Eight integrated circuits accomodate the eight data bits of each of 64K locations of read/write memory. Dynamic RAM IC's are used. 5.2.3.8.2 Read Only Memory A 32K by 8 bit read only memory (ROM) IC is included in the 900XLA. Code and data for the following functions are included: * Power Up Initialization Code * Hardware Interrupt Vector Locations * Kernal Operating System Code * Diskette and Tape Cassette Driver Routines * Computer Keyboard Scanner and Debouncer Code * Floating Point Arithmetic Package * Screen Character Sets * Display Screen Character Editor * Basic Language Interpreter * AMY Drivers to Interpret Musical Scores * AMY Low Level Drivers to Process Sound Event Streams * AMY Data Tables to Simulate a Piano, a Clarinet and a Drum * Interactive Code to Support the Editing and Replay of Musical Scores * Code to Interrogate a Potential Applications Cartridge for Initialization * Code to Interrogate a Potential Applications Diskette for Initialization 5.2.4 Analog Circuitry 5.2.4.1 Video Summation Circuit 5.2.4.2 Audio Summation Circuit The audio summation circuit filters frequencies above 12KHz out of the signal from the AMY I channel and frequencies above 5KHz out of the signal from the POKEY IC. These signals are summed with the signal from the SIO audio input line and after buffering the result is transmitted to the SIO audio output line, the dedicated audio output connector and the TV modulator. ATARI 900XLA HOME COMPUTER *** DRAFT *** Page 6 HARDWARE DESIGN 09 Oct 84 5.2.4.3 R.F. Output 5.2.4.4 A.C. Power Supply System power is supplied by 117VAC 60Hz domestic service. System power consumption does not exceed 20 watts power-up surge or 10 watts during operation. 5.2.5 Keyboard 5.3 EMI And Heat Management 6.0 SOFTWARE EXTERNAL REFERENCE SPECIFICATION 6.1 Purpose 6.1.1 Introduction 6.1.2 Consumer Profile 6.1.3 Interface With Other Products 6.1.4 Family Of Products 6.2 Applicable Documents 6.3 Requirements 6.3.1 Interfaces 6.3.1.1 Physical Requirements 6.3.1.2 Logical Requirements 6.3.1.3 Man/Machine Interface 6.3.2 Functional Requirements 6.3.2.1 Built In BASIC The 900XLA ROM provides revision B ATARI BASIC built in. A cartridge in the cartridge port takes precedence over the BASIC and screen editor in the resident ROM. 6.3.2.2 Built In Sound Editor And Player The 900XLA ROM provides graphical screen editors for musical scores and for parameters which may be used to condition and drive the AMY I sound synthesis IC. The data set generated by this editing process is in a format that can be stored on optional attached ATARI 900XLA HOME COMPUTER *** DRAFT *** Page 7 SOFTWARE EXTERNAL REFERENCE SPECIFICATION 09 Oct 84 diskette drives or tape cassette drives. The data set is in a format such that musical scores may be played in real time from the data set. The data set is in a format such that synchronization information is available to other programs for applications such as synchronized animation. All capabilities of the editor are accessible without peripherals other than a TV or monitor display with sound but certain of the editor operations may be more convenient with a joystick or other input peripheral. 6.3.2.3 Bugs Fixed 6.3.3 Performance 6.3.4 Design Requirements 7.0 COMPATIBILITY WITH EXISTING ATARI PRODUCTS 8.0 PRODUCT IDENTIFICATION
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