An insider‘s guide to reprogrammable logic and its emulation superpowers
Have you ever wondered how retro gaming enthusiasts authentically recreate vintage computers and consoles from the 70s, 80s and 90s? Or how chip designers rapidly prototype upcoming silicon before manufacture? The secret lies in field-programmable gate array (FPGA) hardware emulation – reconfigurable chips able to mimic desired target hardware.
FPGAs empower engineers to model and debug complex systems long before final ASIC production. For retrocomputing fans, FPGAs preserve gaming history by resurrecting defunct platforms. Once an exotic technology, FPGAs now anchor a $16 billion industry thanks continuing improvements in capacity, performance and programming.
This guide will decode FPGAs‘ emulation capabilities and evolution. You‘ll learn:
- How FPGAs provide an agile alternative to fixed-function ASICs
- FPGA advantages in design prototyping, verification and more
- How hobbyists leverage FPGAs to recreate vintage computers and gaming rigs
- Tradeoffs between hardware emulation and software simulation
- Trends pushing FPGAs into ever more ambitious emulation territory
So let‘s dive in and demystify these intriguing chips! Whether an aspiring engineer or retrocomputing enthusiast, unlocking FPGAs‘ flexibility promises exciting opportunities.
Introduction to FPGAs
Before focusing specifically on hardware emulation, let‘s build necessary context by reviewing field-programmable gate array fundamentals.
An FPGA is an integrated circuit containing reconfigurable logic blocks wired together by a flexible interconnect grid. Engineers can customize these generic hardware blocks and networks to implement desired digital functionality after chip manufacture. Hence “field-programmable” – circuit behavior is defined in the field rather than fixed during fabrication.
| FPGA Building Blocks | Description |
|---|---|
| Logic Elements | Basic logic gates like AND/OR to build more complex functions |
| I/O Pads | Physical interface between internal signals and chip pins |
| Interconnect | Reconfigurable wiring between elements to create circuits |
| RAM Blocks | Small local memory stores |
This reusable fabric represents a blank slate for engineers to sculpt into whatever logic circuits an application requires. Want to prototype an experimental CPU or artificial neural network? Or replicate the internals of a 1990s video game console? No problem – just reprogram the FPGA!
FPGAs first emerged in 1984 offering a faster, cheaper alternative to inflexible application-specific integrated circuits (ASICs) dominating the era. Early adoption saw utilization in aerospace and telecommunications for prototypes and small-batch projects before final ASIC production.
Over 30+ years, FPGAs incrementally gained capacity and performance thanks to Moore’s Law. Today’s models integrate upwards of 30 billion transistors – more than many mainstream CPUs! Cutting-edge manufacturing processes allow single chips to implement entire home computers and video game consoles.
We’ll now explore how FPGAs’ unique reconfigurability makes them perfect for hardware emulation.
Why FPGAs Excel at Hardware Emulation
Emulation refers to one system imitation behavior of another. Software emulation simulates hardware through compiled computer code on the host CPU. Hardware emulation goes further – recreating electrical behavior with real physical components.
FPGAs‘ dynamic programmability makes them ideally suited for hardware emulation. These chips become whatever platform you need for development, testing or historical recreation!
Compared to custom ASIC designs, FPGAs offer major advantages:
Reconfigurability
: Instead of fixed function, FPGAs adapt to needs
Faster time-to-market
: Test products before manufacture
Lower NRE costs
: Skip expensive new chip fabrication
Scalability
: Easily upgrade to new standards
Debugging
: Emulation uncovers hardward/software issues
Let‘s explore some use-cases benefiting from FPGAs‘ flexibility.
SoC Prototyping Before Manufacture
With skyrocketing chip fabrication costs, many companies first prototype upcoming silicon designs on FPGAs. Arm‘s new Neoverse V2 CPU architecture for instance runs initial emulation on high-density FPGAs before final manufacture. silicon tapeout. Early software development proceeds smoothly ironing out issues.
Amazon recently revealed its upcoming Graviton3 server CPU undergoes extensive FPGA prototyping before release. Cloud hardware needs rigorous validation before deployment at scale in data centers. FPGA emulation accelerates time-to-market.
Validate Platform Compatibility
Hardware emulation also stresses test platform compatibility across multiple targets. Microsoft engineers emulate upcoming Xbox console CPUs on FPGAs to validate performance. Game developers tap into the same systems when optimizing software. Early risk reduction prevents launch delays.
FPGA provider Xilinx also offers PCIe accelerator cards emulating various AI chips like GPUs and Intel’s Nervana. Data scientists can develop and debug on FPGAs before deploying to expensive specialty hardware.
Video Game History Preservation
Beyond commercial development, FPGAs also serve retrocomputing hobbyists preserving vintage platforms.
The open-source MiSTer project recreates 1980s 8-bit computers and game systems on affordable FPGA dev boards. Commodore 64, Atari 800, Apple II, and 1990s Sega Genesis all live again through meticulous Verilog hardware models. Enthusiasts play classic games with unprecedented accuracy.
Analogue’s aftermarket consoles implement FPGAs imitating the Nintendo Entertainment System and Super Nintendo. Insert original game cartridges to enjoy pixel-perfect, zero latency gameplay like 30+ years ago!
These passion projects demonstrate modern FPGAs‘ power – entire early computing worlds emulated on single chips!
Hardware Emulation vs Software Simulation
How does FPGA hardware emulation differ from pure software platforms simulators?
Software emulation like Nintendo 64 games on PC translates target machine code into host computer instructions. Abstraction layers mimic system buses, graphics and memory. But ultimately still software running on a CPU.
In contrast, FPGA hardware emulation recreates electrical behavior directly in physical hardware logic blocks. The chip becomes the desired system. For example, building digital circuits to match 1980s console processors. Executes natively without software lag.
Hardware emulation provides key advantages:
- More accurate timing/electrical fidelity
- Lower latency
- Bit-perfect I/O
- No software abstraction penalty
Of course increased accuracy comes at the cost of physical hardware complexity compared to pure code. But for applications like chip prototyping requiring high confidence, FPGA emulation shines.
Programming FPGAs for Emulation
To implement digital logic inside an FPGA, engineers use hardware description languages (HDLs) that specify circuit behavior to synthesizer tools. Common languages include:
VHDL
: VHSIC (Very High Speed Integrated Circuit) Hardware Description Language developed by the US Defense Department in 1981 for aerospace and military applications. Known for verbose syntax.
Verilog
: Originally a proprietary HDL by Gateway Design Automation before acceptance as IEEE Standard 1364-1995. Extensively used for digital logic design due to C-like syntax.
SystemVerilog
: Superset of Verilog adding advanced functionality for verification and complex projects.
HDLs describe digital building blocks like logic gates, registers, CPUs at various abstraction levels. Compilers synthesize descriptions into physical FPGA fabric. Engineers leverage languages like Verilog or VHDL to model target hardware. Simulation verifies designs before programming FPGAs.
Pushing Emulation Limits with FPGAs
Early FPGAs in the 1980s only contained several thousand logic gates – sufficient for simple processors and arcade boards but not much more. However staggering leaps in capacity now allow recreation of vastly more powerful 90s systems.
High-end Intel Stratix 10 FPGAs pack over 30 billion transistors – exceeding many commercial CPU chips! Leveraging TSMC’s cutting-edge 3nm fabrication unlocks tremendous gate density. These resources can implement complete home 32-bit consoles and multimedia systems on single chips.
As silicon processes stretch physical limits with smaller geometries and 3D stacking, ever more complex and ambitious emulation targets come within reach. The future may see FPGAs faithfully recreating 128-bit graphical powerhouses like the Sony Playstation 2 and Sega Dreamcast!
Of course software emulation retains simplicity by leveraging readily available PC hardware. But for applications demanding ultimate accuracy like chip prototyping, FPGA logic offers unparalleled flexibility.
Closing Thoughts
This article explored how field-programmable gate arrays enable hardware emulation use-cases impossible with fixed silicon. We covered FPGA capabilities, programming languages enabling custom logic, and recent retrocomputing recreations demonstrating astonishing platforms emulated on single chips.
Whether you’re an aspiring engineer or hobbyist, hopefully this guide provided valuable insight into FPGA hardware emulate and its tremendous potential unlocking new innovation opportunities. The underlying programmable fabric remains virtually unlimited – our creativity is the only limit to imagined systems brought to life!
What obscure computing relic would you resurrect with FPGAs given the chance? Let me know in the comments!
