Homebrew CPUs: Messing around with a J1
Victor Yurkovsky takes James Bowman's compact J1 stack CPU and starts hacking: he trims the ALU, replaces the barrel shifter with simpler shifts, and experiments with dual stacks and memory/IO feeding directly into the ALU. The article walks through small, practical changes that cut logic, add instructions, and boost timing on Spartan-6. It's a hands-on tour that shows how approachable homebrew CPUs can be.
BGA and QFP at Home 1 - A Practical Guide.
It's a myth that BGAs and fine-pitch QFPs can't be soldered at home. Victor Yurkovsky lays out a practical, no-frills approach for hobbyists to design and assemble FPGA boards using 2-layer PCBs, breakout modules, and low-cost reflow methods like toaster ovens or hotplates. The article focuses on manufacturable PCB choices, netlist-driven workflows, and power/decoupling tactics that make high-density parts approachable for amateurs.
Windows XP and Win32 - the Platform of the Future!
Victor Yurkovsky makes the contrarian case that an offline Windows XP VM running Win32 is the most practical platform for modern FPGA development. He explains how Xilinx ISE and related tools often behave far better under XP than on modern Linux distributions, and how VirtualBox fixes USB and GUI headaches. If you maintain FPGA toolchains or write compact C/C++ utilities, this retro setup can save time and frustration.
PC and SP for a small CPU
Victor Yurkovsky walks through a compact stack-based CPU idea that tosses the conventional PC register in favor of a return stack living in Xilinx distributed RAM. The clever twist uses the stack memory addressed by SP as the program counter, making calls trivial and keeping the design tiny. The article shows the Verilog stack module and explains the practical tradeoffs of isolating the return stack.
PicoBlaze - Program RAM Access for an Interactive Monitor
You can give PicoBlaze a live interactive monitor without reconfiguring the FPGA. Victor Yurkovsky walks through using the BRAM's unused port by replacing the assembler template with a dual-ported RAMB16_S18_S18 and exposing maddr, mfromram, mtoram and mwr ports. The post includes IO decoding and a PicoBlaze assembly test to read, write and increment program memory over a serial link.
StrangeCPU #4. Microcode
Victor Yurkovsky shows how a sliding-window opcode scheme turns tiny 8–9 bit tokens into wide microinstructions on an FPGA, letting you pack rich behavior into compact code. The post explains visibility ranges, instruction-data representation, and a low-cost way to add a Red-program counter so runs of microcode execute efficiently with minimal hardware overhead.
StrangeCPU #3. Instruction Slides - The Strangest CPU Yet!
Victor Yurkovsky extends his sliding-window token machine idea to instruction decoding, showing how 8/9-bit tokens can index shared "Blue" memory as 32-bit literals, call targets, or decoded instructions. The approach makes instructions dynamic entries that slide with the window, enabling rare opcodes to be synthesized on demand and reducing fixed opcode bloat. He also covers the 0-bit window (the stack), FPGA BRAM tagging, and the latency trade-offs.
StrangeCPU #2. Sliding Window Token Machines
Victor Yurkovsky walks through a surprising CPU design that expands tiny 8/9-bit tokens into full 32-bit call targets using a sliding-window pointer table. The article explains the red/blue memory model, compilation tradeoffs like table overrun and under-run, literal factoring, FPGA scaling, and even includes an ARM Cortex-M implementation snippet to show how the interpreter works in practice.
StrangeCPU #1. A new CPU
This post rethinks call instructions by factoring call targets out of every callsite and replacing them with tiny tokens. Victor Yurkovsky introduces StrangeCPU, a bytecode CPU that uses 8-bit tokens plus a static sliding-window token table to give byte-long calls full 32-bit reach while dramatically reducing code size. The article includes rationale, tradeoffs, a simple proof-of-concept x86 interpreter, and the basic lookup equation for hardware implementation.
VGA Output in 7 Slices. Really.
Victor Yurkovsky shows how to generate VGA timing on a Xilinx Spartan3 using clever SRL16 tricks to squeeze the generator into just a few slices. By using 32-bit SRLs for line pulses, two mutually prime SRL lengths as a divide-by-99 timebase, and tapped SRLs to combine HSYNC and HBLANK, the approach achieves accurate-enough horizontal and vertical timing with minimal LUT usage.
BGA and QFP at Home 1 - A Practical Guide.
It's a myth that BGAs and fine-pitch QFPs can't be soldered at home. Victor Yurkovsky lays out a practical, no-frills approach for hobbyists to design and assemble FPGA boards using 2-layer PCBs, breakout modules, and low-cost reflow methods like toaster ovens or hotplates. The article focuses on manufacturable PCB choices, netlist-driven workflows, and power/decoupling tactics that make high-density parts approachable for amateurs.
Homebrew CPUs: Messing around with a J1
Victor Yurkovsky takes James Bowman's compact J1 stack CPU and starts hacking: he trims the ALU, replaces the barrel shifter with simpler shifts, and experiments with dual stacks and memory/IO feeding directly into the ALU. The article walks through small, practical changes that cut logic, add instructions, and boost timing on Spartan-6. It's a hands-on tour that shows how approachable homebrew CPUs can be.
StrangeCPU #1. A new CPU
This post rethinks call instructions by factoring call targets out of every callsite and replacing them with tiny tokens. Victor Yurkovsky introduces StrangeCPU, a bytecode CPU that uses 8-bit tokens plus a static sliding-window token table to give byte-long calls full 32-bit reach while dramatically reducing code size. The article includes rationale, tradeoffs, a simple proof-of-concept x86 interpreter, and the basic lookup equation for hardware implementation.
PC and SP for a small CPU
Victor Yurkovsky walks through a compact stack-based CPU idea that tosses the conventional PC register in favor of a return stack living in Xilinx distributed RAM. The clever twist uses the stack memory addressed by SP as the program counter, making calls trivial and keeping the design tiny. The article shows the Verilog stack module and explains the practical tradeoffs of isolating the return stack.
VGA Output in 7 Slices. Really.
Victor Yurkovsky shows how to generate VGA timing on a Xilinx Spartan3 using clever SRL16 tricks to squeeze the generator into just a few slices. By using 32-bit SRLs for line pulses, two mutually prime SRL lengths as a divide-by-99 timebase, and tapped SRLs to combine HSYNC and HBLANK, the approach achieves accurate-enough horizontal and vertical timing with minimal LUT usage.
Windows XP and Win32 - the Platform of the Future!
Victor Yurkovsky makes the contrarian case that an offline Windows XP VM running Win32 is the most practical platform for modern FPGA development. He explains how Xilinx ISE and related tools often behave far better under XP than on modern Linux distributions, and how VirtualBox fixes USB and GUI headaches. If you maintain FPGA toolchains or write compact C/C++ utilities, this retro setup can save time and frustration.
StrangeCPU #2. Sliding Window Token Machines
Victor Yurkovsky walks through a surprising CPU design that expands tiny 8/9-bit tokens into full 32-bit call targets using a sliding-window pointer table. The article explains the red/blue memory model, compilation tradeoffs like table overrun and under-run, literal factoring, FPGA scaling, and even includes an ARM Cortex-M implementation snippet to show how the interpreter works in practice.
StrangeCPU #3. Instruction Slides - The Strangest CPU Yet!
Victor Yurkovsky extends his sliding-window token machine idea to instruction decoding, showing how 8/9-bit tokens can index shared "Blue" memory as 32-bit literals, call targets, or decoded instructions. The approach makes instructions dynamic entries that slide with the window, enabling rare opcodes to be synthesized on demand and reducing fixed opcode bloat. He also covers the 0-bit window (the stack), FPGA BRAM tagging, and the latency trade-offs.
FPGA Assemblers and Time Machines
Modern FPGA toolchains have turned tinkering into a slog, Victor Yurkovsky recalls the old joy of manual hardware hacking and wants it back. He proposes an assembler-style approach, exemplified by the proposed 'fpgasm', that preserves placement and routing, programs bitstreams in seconds, and makes live probing and rapid iteration practical again. Read this to see why low-level control could revive hands-on FPGA learning.
PicoBlaze - Program RAM Access for an Interactive Monitor
You can give PicoBlaze a live interactive monitor without reconfiguring the FPGA. Victor Yurkovsky walks through using the BRAM's unused port by replacing the assembler template with a dual-ported RAMB16_S18_S18 and exposing maddr, mfromram, mtoram and mwr ports. The post includes IO decoding and a PicoBlaze assembly test to read, write and increment program memory over a serial link.
StrangeCPU #1. A new CPU
This post rethinks call instructions by factoring call targets out of every callsite and replacing them with tiny tokens. Victor Yurkovsky introduces StrangeCPU, a bytecode CPU that uses 8-bit tokens plus a static sliding-window token table to give byte-long calls full 32-bit reach while dramatically reducing code size. The article includes rationale, tradeoffs, a simple proof-of-concept x86 interpreter, and the basic lookup equation for hardware implementation.
BGA and QFP at Home 1 - A Practical Guide.
It's a myth that BGAs and fine-pitch QFPs can't be soldered at home. Victor Yurkovsky lays out a practical, no-frills approach for hobbyists to design and assemble FPGA boards using 2-layer PCBs, breakout modules, and low-cost reflow methods like toaster ovens or hotplates. The article focuses on manufacturable PCB choices, netlist-driven workflows, and power/decoupling tactics that make high-density parts approachable for amateurs.
StrangeCPU #2. Sliding Window Token Machines
Victor Yurkovsky walks through a surprising CPU design that expands tiny 8/9-bit tokens into full 32-bit call targets using a sliding-window pointer table. The article explains the red/blue memory model, compilation tradeoffs like table overrun and under-run, literal factoring, FPGA scaling, and even includes an ARM Cortex-M implementation snippet to show how the interpreter works in practice.
Homebrew CPUs: Messing around with a J1
Victor Yurkovsky takes James Bowman's compact J1 stack CPU and starts hacking: he trims the ALU, replaces the barrel shifter with simpler shifts, and experiments with dual stacks and memory/IO feeding directly into the ALU. The article walks through small, practical changes that cut logic, add instructions, and boost timing on Spartan-6. It's a hands-on tour that shows how approachable homebrew CPUs can be.
VGA Output in 7 Slices. Really.
Victor Yurkovsky shows how to generate VGA timing on a Xilinx Spartan3 using clever SRL16 tricks to squeeze the generator into just a few slices. By using 32-bit SRLs for line pulses, two mutually prime SRL lengths as a divide-by-99 timebase, and tapped SRLs to combine HSYNC and HBLANK, the approach achieves accurate-enough horizontal and vertical timing with minimal LUT usage.
StrangeCPU #3. Instruction Slides - The Strangest CPU Yet!
Victor Yurkovsky extends his sliding-window token machine idea to instruction decoding, showing how 8/9-bit tokens can index shared "Blue" memory as 32-bit literals, call targets, or decoded instructions. The approach makes instructions dynamic entries that slide with the window, enabling rare opcodes to be synthesized on demand and reducing fixed opcode bloat. He also covers the 0-bit window (the stack), FPGA BRAM tagging, and the latency trade-offs.
PC and SP for a small CPU
Victor Yurkovsky walks through a compact stack-based CPU idea that tosses the conventional PC register in favor of a return stack living in Xilinx distributed RAM. The clever twist uses the stack memory addressed by SP as the program counter, making calls trivial and keeping the design tiny. The article shows the Verilog stack module and explains the practical tradeoffs of isolating the return stack.
StrangeCPU #4. Microcode
Victor Yurkovsky shows how a sliding-window opcode scheme turns tiny 8–9 bit tokens into wide microinstructions on an FPGA, letting you pack rich behavior into compact code. The post explains visibility ranges, instruction-data representation, and a low-cost way to add a Red-program counter so runs of microcode execute efficiently with minimal hardware overhead.
FPGA Assemblers and Time Machines
Modern FPGA toolchains have turned tinkering into a slog, Victor Yurkovsky recalls the old joy of manual hardware hacking and wants it back. He proposes an assembler-style approach, exemplified by the proposed 'fpgasm', that preserves placement and routing, programs bitstreams in seconds, and makes live probing and rapid iteration practical again. Read this to see why low-level control could revive hands-on FPGA learning.
Windows XP and Win32 - the Platform of the Future!
Victor Yurkovsky makes the contrarian case that an offline Windows XP VM running Win32 is the most practical platform for modern FPGA development. He explains how Xilinx ISE and related tools often behave far better under XP than on modern Linux distributions, and how VirtualBox fixes USB and GUI headaches. If you maintain FPGA toolchains or write compact C/C++ utilities, this retro setup can save time and frustration.
