RealDOOM

RealDOOM is an in progress port of the DOS version of DOOM (based on PCDOOMv2) to Real Mode, to support 16-bit processors (namely the 8088 and 286). It is meant to be accurate to the original game and id software WADs first and foremost. So it should work with timedemos, and have the support for the same level of graphical detail as the original game.

As of release 0.11, the game is fully playable with the shareware DOOM1.WAD file.

The current development focus is on stability and architecture rather than speed improvements, which will come after the engine is in a more realmode-friendly state.

To build an optimized 80286 build, run make286.bat. Otherwise, run make16.bat for 8088 support.

As of version 0.15, the game is no longer compatible with DOSBox because DOSBox lacks support from EMS 4.0 multitasking features.

If running on real hardware, a pentium or fast 486 is current recommended.

Removed features (not planned to be re-added)

• multiplayer and netplay
• joystick support

Broken/unimplemented features (planned to be fixed)

• sound (will require a 16 bit library)
• savegames (will require a rewrite of the archive/unarchive code)

There are also a lot of hard caps on things like texture size and count, node count, etc, which will probably make many custom WADs unplayable. oh well.

Known bugs:

• content outside of doom1 shareware has not been tested at all and wont work
• there is a particular render bug with fuzz draws, it comes up twice in demo3 early on where you see a vertical fuzzy line drawn around the first spectre towards when its killed. not sure the cause of this yet.

High-Level Roadmap:

Not necessarily meant to be accurate, but just to give an overview of the general order in which things are probably going to be built.

v0.10 release: mostly stable shareware demo

v0.11 release: UMB usage and all shareware demos playable. Last EMS 3.2 compatible version?

• render bugfixes
• use UMBs if available - e1m6 now playable

v0.15 : EMS 4.0 multitasking features

• EMS 4.0 multitasking
  • dynamic allocations in the 256-640KB memory range
  • level data and things broken into physics/render regions
  • texture cache added for more textures in memory during render
  • using full sine tables again
  • visplane cap only 60 for now, to be fixed in 0.16
  • removed use of page frame
• Some fixes and additions:
  • fixed fwipe (screen wipe)
  • fixed intermission animations
  • fixed finale
  • added 286 build option

v0.16 : EMS 4.0 multitasking features

• medium memory model
• re-implement dynamic visplane allocation
• texture cache improvements

v0.20 : Commercial game/feature support

• doom 1 wad support?
• fix save/load game?

v0.21 : Commercial game/feature support

• doom 2 wad support?

v0.23 : ASM improvements

• some level of early easy asm work (math functions?)

v0.24 : ASM improvements

• core drawing functions rewritten in asm

v0.30 : ASM improvements

• full render pipeline written in asm and runtime-loaded/linked render asm

v0.31 : Full feature compatibility?

• sound code?

v0.xx : Continued improvement

• continued moving of code to asm, optimizations, etc
  • physics code profiled, some main loops written in asm?
  • manually written overlay code, more dynamic linking to free more space?

v0.??

• highly optimized but non-timedemo conformant 286 super-optimized version?

Speed

Current Realtics/FPS for timedemo3 with screenblocks 5 and high quality:

Machine Specs	86box	FPS	Real Hardware	FPS
Pentium MMX 233	1148	65.06	830	89.99
Pentium 133	1695	44.06
AMD 5x86 P90	2637	28.32
486 DX2-66	5637	13.25
486 SX-33	10529	7.09
386 DX-40	12989	5.75	12534	5.96
286-25	31821	2.35
286-20			32377	2.31
v20 9.5 MhZ			162157	0.46
8088 4.77 MhZ (NuXT)			351970	0.21
8088 4.77 MhZ (5150)			384254	0.19

I think we are looking for around 5-10x performance uplift from the current point to reach playability on fast 286es.