Программный эмулятор рабочей станции Кронос

Архив исходных текстов эмулятора рабочей станции Кронос и операционной системы Excelsior, разработанных в Новосибирском Вычислительном центре СО АН СССР в рамках проекта МАРС (Модульные Асинхронные Развиваемые Системы) во второй половине 1980-х

Для архивного постоянного хранения

Все права принадлежат разработчикам системы Семейство процессоров Кронос

Kronos CPU on FPGA

Kronos is a 32-bit stack/RISC CPU designed in Novosibirsk (1984–1991) to run the Excelsior iV operating system. This repository pairs the upstream Kronos3vm software emulator and the full Excelsior OS sources with FPGA implementations of the CPU, plus a resurrected Kronos C toolchain.

The vendor-neutral Kronos core lives in vm/vhdl/5.0; each board implementation adapts that shared core to specific silicon.

Prerequisites

Different parts of the repo need different tools:

To build…	You need
The Kronos3vm emulator (vm/int)	CMake ≥ 3.5, SDL2, a C++ compiler (gcc/clang)
An FPGA bitstream	the board's vendor toolchain — the OneChipBook needs Quartus II 11.0sp1 (see its README)
Simulations (GHDL testbenches)	GHDL (--std=93)
The SD-card / disk-image builders and host tools	Python 3
The Kronos C toolchain (vm/pcc-host)	a host C compiler (gcc) — see vm/pcc-host/build.sh

FPGA implementations

Target	Board / FPGA	Status
Xilinx Spartan-3 (vm/vhdl/5.0/board)	Digilent Spartan-3 Starter Board (DigilentSpartan3StarterBoard.vhdl) and Xilinx SP305 (XilinxSpartan3SP305.vhdl)	The reference FPGA implementations (Kronos + serial + ATA).
OneChipBook (vm/vhdl/onechipbook_kronos)	OneChipBook 1.2 — Altera Cyclone EP1C12, 32 MB SDRAM, VGA, PS/2, SD	Boots the real Excelsior OS interactively on hardware.

OneChipBook port

The OneChipBook port takes the Kronos core to an Altera Cyclone EP1C12 board and boots the genuine Excelsior OS from an SD card into SDRAM, running it as an interactive workstation on real silicon — VGA text console, PS/2 keyboard, SD read/write, a 2-way write-back data cache (≈7× the uncached core — ~15,000 Dhrystones), suspend-to-RAM, and a self-hosting C compiler, all on the FPGA. Its Cyclone-adapted VHDL (cache and memory copies) lives in its own src/ so the shared core is never edited in place.

• vm/vhdl/onechipbook_kronos/README.md — what works, the prerequisites and step-by-step build/flash/SD-card guide, how to simulate, and the host tooling.
• vm/vhdl/onechipbook_kronos/doc/DESIGN.md — the design + bring-up story (the Kronos instruction-set gap, boot flow, disk layout, and how the boot fault was root-caused and fixed).

The Excelsior OS

Kronos3vm is a software emulator of the Kronos computer; it runs Excelsior iV and ships with the full OS source, ready for system builds.

• Sources: excelsior/src — the complete Excelsior iV system (kernel sys/, firmware fw/, shell + utilities, fonts, and user accounts under users/).
• Documentation: excelsior/src/doc — the Excelsior manuals (adm, ar1–ar3, lib, pr, shell, util1/util2).
• Disk images: excelsior/xd — the bootable OS volumes (xd0.dsk = boot, xd1.dsk = system/root).

Running it under the emulator

The vm/int emulator is the reference oracle the FPGA work is validated against (a portable CMake/SDL build sits alongside the original Visual Studio project):

cd vm/int && cmake -B build && cmake --build build
./build/kronos_vm ../../excelsior/xd/xd0.dsk ../../excelsior/xd/xd1.dsk

At the user: prompt, log in as sys — you'll get a shell prompt like 17:12 sys ! (the time, the current directory, and !). Type ls to look around.

Using the OS

The Excelsior command interface is Unix-like:

• ls, cd, cp, rm, ln, cat — the familiar file utilities.
• kc — a Norton-Commander-style file manager (more convenient than raw ls/cd).
• ex — the text editor.
• mx — the Modula-2 compiler (the docs call it m2, which is now outdated).
• Executables are .cod files — run one by typing its name without the extension. Scripts have the .@ or .sh extension.
• Most utilities print usage with the -h switch.

The Kronos C toolchain

vm/pcc-host/ is the Kronos pcc C compiler, cross-built on Linux and emitting Kronos .cod. It self-hosts: a C program can be compiled entirely on the Excelsior OS (cpp → pcc → a_asm → clink) and the resulting .cod loads and runs. The ctool_scripts/ are the on-board driver scripts, and vm/pcc-host/ktool/ packages the compiler + runtime + headers into an SD volume.

Repository map

excelsior/            Excelsior OS sources (src/), docs (src/doc/), disk images (xd/)
vm/
  int/                Kronos3vm software emulator (VS project + portable CMake/SDL build)
  pcc-host/           Kronos C compiler host toolchain (cpp / pcc / a_asm / clink)
  uart/               UART host tools (serial console + file transfer)
  xdu/, client/       disk / client utilities (upstream)
  vhdl/
    5.0/              vendor-neutral Kronos core + Xilinx Spartan-3 reference boards
    onechipbook_kronos/   OneChipBook (Cyclone EP1C12) port
ctool_scripts/        on-board C-compiler driver scripts

Upstream

• Kronos: https://kronos.ru/
• Repo: https://github.com/leok7v/kronos (this fork adds the FPGA ports and C toolchain)