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Model Groups 4 & 5 announced
09/15/83, withdrawn 02/17/87.
ModelGroup 3 announced 09/12/84The following is the text of an IBM Information Systems Group press fact sheet distributed on September 10, 1984.

• Commercial performance equivalent to the 4331 model 2.
• Factory installed option increases engineering/scientific performance up to 1.4 times the model 2 for short precision and 2.2 times for long precision.
• High-Accuracy Arithmetic Facility:
  • Allows computational procedures with algorithmic verification of results.
  • New floating-point instructions are implemented for computation of basic arithmetic operations and the scalar product with maximum accuracy.
  • Provides direct rounding for the short and long floating-point hexadecimal formats.
• Microcode-assisted support for improved performance of frequently used mathematical functions.
• 2 or 4MB of processor storage.
• Integrated I/O attachments and standard I/O interface channels for maximum system configuration flexibility.
• Integrated DASD Adapter support.
• Up to three data channels.
• Field upgradable to models 4 and 5.
• Extensive programming support, including VM/SP, SSX/VSE, VSE/SP and OS/VS1.

• Serial OEM Interface -- for attaching a variety of non-IBM subsystems, workstations and devices. Board-level microcomputer devices attach to the interface with adapters that provide conversions and control functions.
• Programmable Power-Off -- enables the user to turn off the processor under program control.
• Problem Determination -- three software tools for user-initiated problem determination: Problem Finder Facility, System Event Trace and System Status Display.

• Workstation Adapter -- supports the following features/functions beyond the Display/Printer Adapter:
  • 3270 extended datastream for extended highlighting.
  • Seven colors and programmed symbols.
  • Screen sizes up to 3,564 characters.
  • APL keyboard.
  • Combination of both adapters provides 40 ports for attachment of workstations including IBM Displaywriters and Personal Computers.
• Auto-Start -- automatically turns on the processor by telephone via the Remote Operator Control Facility or at a predetermined time and day of the week. The processor powers on and proceeds with initial microcode load, sets the clock and loads the system.

• Standard feature for models 4 and 5.
• Factory installed option for model 3.
• Improves multiplication execution times by a factor of 3 to 8 over microcode implementations.
• Uses high-speed array multiplier logic.