AHDL vs. VHDL — understanding language scope and ownership What is the basic difference between AHDL (Altera Hardware Description Language) and VHDL in the context of PLD/FPGA design?

Introduction / Context:
Hardware description languages specify digital hardware behavior and structure. VHDL is an IEEE-standard language used across vendors, whereas AHDL was created by Altera (now part of Intel) for their tools. Knowing which language is standardized versus proprietary helps when choosing a design flow that is portable across devices.

Given Data / Assumptions:

• AHDL originates from a single vendor ecosystem.
• VHDL is an IEEE standard (IEEE 1076).
• Target devices include PLDs and FPGAs.

Concept / Approach:
Proprietary languages are controlled by one company and may be supported primarily in that company's toolchain. Standardized languages are maintained by standards bodies and widely supported across EDA tools and vendors. Therefore, AHDL is proprietary to Altera's environment, while VHDL is a vendor-neutral, standardized HDL.

Step-by-Step Solution:

Verification / Alternative check:
Tool documentation historically lists AHDL support within Altera/Intel Quartus; VHDL is supported in nearly all mainstream FPGA workflows.

Why Other Options Are Wrong:

• AHDL or VHDL used in all PLDs: exaggerated and incorrect.
• VHDL is proprietary: false; it is an open standard.

Common Pitfalls:
Assuming “used everywhere” equals “standard”; vendor adoption does not change IEEE standard status.

Final Answer:
AHDL is proprietary.