مدار مجتمع (آی سی) آی سی‌کاربرد ویژه

Product Attributes

Introduction

The AM2910A Microprogram Controller is an address sequencer that controls the execution order of microinstructions stored in microprogram memory. In addition to sequential access capability, it supports conditional branching to any microinstruction within a 4096-microword range. A LIFO stack provides microsubroutine return linkage and looping capability, with nine levels of microsubroutine nesting. The microinstruction loop count control has a counting capacity of 4096. During each microinstruction cycle, the microprogram controller provides a 12-bit address from one of four sources: 1) the Microprogram Address Register (μPC), which normally holds an address one greater than the previous address; 2) an external (direct) input (D); 3) a register/counter (R) that retains data loaded during a previous microinstruction; 4) a 9-level-deep LIFO stack (F). The AM2910A is a speed-enhanced drop-in replacement for the Am2910, fabricated using AMD's Ion-implanted Micro-OXide (IMOX) process, achieving a 25–30% speed improvement. Compared to the 5-level-deep stack of the Am2910, the AM2910A also features a 9-word-deep stack.

Features

• 12-bit wide: A single chip can address up to 4096 words of microcode; all internal elements are full 12-bit wide.
• Internal loop counter: Presettable 12-bit down counter for repeating instructions and counting loop iterations.
• Four address sources: Microprogram address selectable from microprogram counter, branch address bus, 9-level push/pop stack, or internal holding register.
• Sixteen powerful microinstructions: Executes 16 sequencer control instructions, most of which depend on external condition inputs, internal loop counter status, or both.
• Output enable control for three branch address sources: Built-in decoder function for connecting external devices to the branch address bus without external decoder.
• High speed: AM2910A supports 100ns cycle time, 25–30% faster than Am2910.