PCem

PCem (short for PC Emulator) is an IBM PC emulator for Windows and Linux that specializes in running old operating systems and software that are designed for IBM PC compatibles. Originally developed as an IBM PC XT emulator, it later emulates other IBM PC compatible computers as well.

PCem
Screenshot of PCem running FreeDOS 1.0
Developer(s)Sarah Walker (including contributors)
Initial releaseAugust 15, 2007 (2007-08-15)
Stable release
15 / May 19, 2019 (2019-05-19)
Written inC
Operating systemMicrosoft Windows, Linux
TypeVirtual machine, emulator
LicenseGNU GPL version 2
Websitepcem-emulator.co.uk

Unofficial builds of PCem are also available, such as 86Box, which includes a number of enhanced features, including SCSI and some new boards. Versions of PCem from v0.5 until v8 have been removed from the official webpage, due to the use of the MAME OPL2 and OPL3 emulation code from when it was not yet licensed under a GPL-compatible license.

Features

Hardware

PCem is capable of emulating Intel processors (and its respective clones, including AMD, IDT and Cyrix) from Intel 8088 through the Pentium Tillamook MMX/Mobile MMX processors from 1997 until 1999. A recompiler has been added in v10.1, being mandatory for P5 Pentium and Cyrix processors and optional for i486 processors and IDT WinChip processors. Yet a rather fast processor is needed for full emulation speed (such as an Intel Core i5 at 4 gigahertz). However, the current developer of PCem has a main concern that the recompiler is not fast enough to emulate the Intel Pentium Pro/Pentium II processors yet.[1]

PCem emulates various IBM PC compatible systems/motherboards from 1981 until 1996, this includes almost all IBM PC models (including the IBM PS/1 model 2121 and the IBM PS/2 model 2011), some American Megatrends BIOS clones (from 1989 until 1994), Award BIOS systems (Award 286 clone, Award SiS 496/497 and Award 430VX PCI), and Intel Premiere/PCI and Intel Advanced/EV motherboards.[2] However, unofficial builds of PCem (PCem-X and PCem-unofficial) also supports IBM PC compatible systems/motherboards (from 1996 until 2000) that supports Intel Pentium Pro/Pentium II processors. PCem simulates the BIOS cache, which relies on the processor rather than on system memory.

PCem can emulate different graphic modes, this includes text mode, Hercules, CGA (including some composite modes and the 160x100x16 tweaked modes), Tandy, EGA, VGA (including Mode X and other tweaks), VESA, as well as various video APIs such as DirectX and 3Dfx's Glide. PCem can also emulate various video cards such as the ATI Mach64 GX, the S3 Trio32/64/Virge series and the 3Dfx Voodoo.

PCem also emulates some sound cards, such as the AdLib, Sound Blaster (including the Game Blaster), Sound Blaster Pro, Sound Blaster 16, Sound Blaster AWE32, Gravis UltraSound, Innovation SSI-2001, Windows Sound System, Ensoniq AudioPCI 64V/ES1371, and Sound Blaster PCI 128.[2]

Voodoo emulation is also emulated since PCem v10 and PCem v12, which added support for Voodoo 2 and various optimizations.[3] However, there some shortcomings regarding Voodoo emulation such as the lack of mip-mapping, slightly wobbling triangles, lack of speed limiting, and wrong refresh rates on almost every resolution (except 640x480@60 Hz).[4] As of PCem v11, a separate recompiler has been added for Voodoo emulation, making it faster to emulate the Voodoo graphics card.

An unofficial build of PCem allows to use SLiRP/WinPcap as a networking interface, plus emulated NE2000 and Realtek RTL8029AS Ethernet cards. However, starting with PCem v13, the emulation of NE2000 was officially added.

Operating system support

Similar to Virtual PC, Bochs and QEMU, it emulates almost all versions of Microsoft Windows until Windows Vista (including Service Pack 2), MS-DOS, FreeDOS and CP/M-86 are also supported. Earlier versions of OS/2 requires the hard drive to be formatted prior to installation, while OS/2 Warp 3 until Warp 4.5 requires an unaccelerated video card to run. Other operating systems are also supported on PCem, such as versions of Linux that supports the Pentium processor, BSD derivatives (e.g. FreeBSD), and BeOS 5, which only works on the Award SiS 497 motherboard.

Version history

PCem version Release date Notes
v0.1 15 August 2007 Initial release
v0.2 10 October 2007
  • Added Amstrad PC1640 and IBM AT emulation
  • Added Intel 80286 processor emulation
  • Added Paradise EGA and Trident VGA emulation
  • Added Sound Blaster 2.0 emulation
  • Added hard disk emulation
  • Numerous bug fixes and improvements
v0.2a 14 October 2007
  • Numerous bug fixes
v0.3 30 July 2008
v0.4 27 July 2010
v0.41 1 February 2011
v0.41a 13 February 2011
  • Numerous bug fixes
    • Fixed disk corruption bug
v0.5 21 September 2011
  • Supported more games (Tyrian, Jazz Jackrabbit, Transport Tycoon)
  • Added cache emulation
  • Added Soundblaster Pro v2 and Sound Blaster 16 emulation
  • Added CD-ROM emulation
  • Re-added CGA Composite emulation
  • Numerous bug fixes and improvements
    • Added 80486 speed options between 50 and 120 MHz
    • Fixed CMOS corruption bug
    • GUS improvements for MIDI playback
    • 8088/8086 timing tweaks
    • Fixed bugs in LLDT/LIDT/LGDT/LTR
    • VM flag no longer stored with PUSHFD
    • Fixed bug in SIDT/SGDT - no more 'hardware not recognized' from Borland DPMI
    • HLT now priviledged
    • Fixed unused bits in FLAGS register
    • Fixed read/write across page boundary
    • Many bug fixes in exception handling
    • REP INSx now uses correct segment
    • DIV.D fixed (Terminal Velocity, Pro Pinball)
    • Other fixes and changes
v0.6 19 December 2011
  • Supported more games (Quake, Grand Theft Auto, X-COM: Apocalypse)
  • Supported more systems (Windows 3.x in 386 Enhanced Mode, Windows 95)
  • Added Intel 80486 DX FPU emulation.
  • Added Dell System 200, Acer 386SX/25N, WinBIOS 486 BIOSes support
  • Added Soundblaster Pro and Sound Blaster 16 mixers emulation
  • Numerous bug fixes and improvements
    • Fixed page fault issue
    • Fixed CD-ROM Read sub-channel command, music on Quake and Grand Theft Auto works properly
    • Fixed MOV exx,sreg
    • Fixed IO port trapping
    • Fixed LAR instruction
    • Implemented MMU permissions for Windows 95
    • Timer fixes
    • Fixed VGA address register reads
    • Fixed Trident banking registers (among other things) for MicroProse installers
    • Implemented trap flag and fixed interrupt behaviour (Second Reality demo)
    • Fixed numerous bugs with PPI & PIT
    • Floppy controller fixes
    • Memory limit increased from 16MB to 64MB
    • Hard disk limit increased from 512MB to 2GB
    • Other fixes and changes
v0.7 3 August 2012
  • New machines - DTK XT clone, Amstrad PC2086/PC3086, Olivetti M24, Commodore PC-30 III, PCI 486 clone
  • New graphics cards - IBM EGA, Diamond Stealth 32 (ET4000/W32p), Paradise Bahamas 64 (S3 Vision864)
  • Supported more systems and programs (Windows 3.x in 386 Enhanced Mode, Windows 98, Internet Explorer 4, Linux)
  • Added IDE hard disk emulation (Replaced the old INT 13 trapping emulation on all models)
  • Numerous bug fixes and improvements
    • Fixed wrong code segment on page fault - eliminates some Windows 95 crashes
    • Fixed trap flag on POPF/IRET - improves DOS box on Windows 95
    • Fixed various pmode stuff, OS/2 v1.3 works
    • Fixed MMU caching bug
    • Major improvements to floppy disk emulation - fixed occasional disk corruption, works with OS/2 and Linux
    • ATAPI identify command now returns an ATAPI version, Windows 95 native CD-ROM drivers now work
    • CD-ROM emulation now uses raw read for audio - works on Windows 7
    • Major internal changes to graphics emulation
    • Major internal changes to memory and IO emulation
    • Other fixes and changes
v8 20 December 2013
v8.1 3 January 2014
  • Numerous bug fixes and improvements
    • Fixed various issues with ROM detection/loading
    • Implemented DMA controller disable, fixed PC2086/3086
    • Switched IBM XT BIOS from 01/10/86 version to 11/08/82
    • Fixed stuck keys on XT and Amstrad machines
  • Replaced the non-free MAME OPL2/OPL3 emulation code with a GPL-licensed OPL2/OPL3 emulation code
v9 4 October 2014
  • New machines - IBM PCjr
  • New graphics cards - Diamond Stealth 3D 2000 (S3 ViRGE/325), S3 ViRGE/DX
  • New sound cards - Innovation SSI-2001 (using ReSID-FP)
  • Added joystick emulation
  • Added preliminary Linux port
  • Numerous bug fixes and improvements
    • CPU fixes (Windows NT now works, OS/2 2.0+ works better)
    • Fixed issue with port 3DA when in blanking, DOS 6.2/V now works
    • Re-written PIT emulation
    • IRQs 8-15 now handled correctly, Civilization no longer hangs
    • Fixed vertical axis on Amstrad mouse
    • Serial fixes - fixes mouse issues on Windows 3.x and OS/2
    • New Windows keyboard code - should work better with international keyboards
    • Changes to keyboard emulation - should fix stuck keys
    • Some CD-ROM fixes
v10 24 October 2015
  • New machines - AMI XT clone, DTK XT clone, VTech Laser Turbo XT, VTech Laser XT3, Phoenix XT clone, Juko XT clone, IBM PS/1 model 2011, Compaq Deskpro 386, DTK 386SX clone, Phoenix 386 clone, Intel Premiere/PCI, Intel Advanced/EV
  • New graphics cards - IBM VGA, 3dfx Voodoo Graphics
  • Added Pentium and Pentium MMX emulation
  • Added experimental dynamic recompiler (up to 3x speed-up)
  • Improved floppy-disk controller emulation
    • Added FDI images support
    • Added 1.2MB 5.25" floppy drive emulation
    • Added write protect support
  • Added support for up to 4 IDE hard drives
  • Numerous bug fixes and improvements
v10.1 7 November 2015
  • Fixed buffer overruns in PIIX and ET4000/W32p emulation
  • Added command line options to start in fullscreen and to specify config file
  • Fixed emulator crash when the CPU jumps to an unexecutable address
  • Removed Voodoo memory dump on exit
v11 5 June 2016
  • New machines - Tandy 1000HX, Tandy 1000SL/2, Award 286 clone, IBM PS/1 model 2121
  • New graphics card - Hercules InColor
  • Added 3DFX recompiler (2-4x speedup over previous emulation)
  • Added Cyrix 6x86 emulation
  • Added IBM PS/1 audio card emulation
  • Added Adlib Gold surround module emulation
  • Added Gravis Ultrasound stereo support
  • Improved floppy-disk controller emulation
    • Added support for more drive types
    • Added FIFO emulation
    • Better support of XDF images add FDI
  • Added direct support to ISO image for CD-ROM emulation
  • Improved CD-ROM emulation
    • Configurable CD-ROM IDE channel
    • improved disk change handling
    • Better volume control support
  • Numerous bug fixes and improvements
    • Some optimizations to dynamic recompiler
    • Fixed broken 8088/8086 timing
    • Fixes to Mach 64 and ViRGE 2D blitters
    • XT machines can now have less than 640KB RAM
    • Fixes to PCjr/Tandy PSG emulation
    • Fixed crash when using Direct3D output on Intel HD graphics
    • Other fixes and changes
v12 18 February 2017
  • New machines - AMI 386DX, MR 386DX
  • New graphics cards - Plantronics Colorplus, Wyse WY-700, Obsidian SB50, Voodoo2
  • CPU optimizations
  • 3DFX optimizations
  • Added Basic 80286/80386 prefetch emulation
  • Mouse can be selected between serial, PS/2, and IntelliMouse
  • Improved joystick emulation
    • Analogue joystick up to 8 buttons
    • Added CH Flightstick Pro, ThrustMaster FCS, Microsoft SideWinder support
  • Improved CGA/PCjr/Tandy composite emulation
  • Numerous bug fixes
v13 11 December 2017
v14 20 April 2018
v15 19 May 2019
  • New machines - Zenith Data SupersPORT, Bull Micral 45, Tulip AT Compact, Amstrad PPC512/640, Packard Bell PB410A, ASUS P/I-P55TVP4, ASUS P/I-P55T2P4, Epox P55-VA, FIC VA-503+
  • New graphics cards - Image Manager 1024, Sigma Designs Color 400, Trigem Korean VGA
  • Added emulation of AMD K6 family and IDT Winchip 2
  • New CPU recompiler
  • Added experimental ARM and ARM64 host support
  • Added read-only cassette emulation for IBM PC and PCjr
  • Numerous bug fixes

See also

References

  1. "PCem • View topic - A mere idea for a future chipset (440FX)". pcem-emulator.co.uk. Retrieved 2016-08-08.
  2. "PCem". pcem-emulator.co.uk. Retrieved 2016-08-07.
  3. Cauterize. "Vintage Computer Emulator 'PCem' Now Running 3Dfx Based Windows Games". Retrieved 2016-08-07.
  4. "PCem • View topic - 3DFX emulation". pcem-emulator.co.uk. Retrieved 2016-08-07.
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