Win994a-TI-99/4A Simulator for Windows

Version 3.010

Win994a Boot

Win994a is a TI-99/4A simulator written by Cory Burr that installs and runs in the Windows environment.  It was written to simulate  the TI-99/4A, not to emulate it perfectly.  

General Functionality:
  1. Boots and runs all console ROM and GROM based functions including console BASIC.
  2. CRU bits for the keyboard are implemented; some CRU bits for the Disk Controller and RS232 Interface are implemented.
  3. TMS9918a video chip functionality is fully implemented.
  4. TMS9919 sound chip functionality is fully implemented.
  5. TMS5220 speech synthesizer chip data transport is fully implemented. Speech text is displayed in a scrolling marquee, in addition to being spoken.
  6. Full floppy disk and disk controller functionality.
  7. Full cassette tape functionality for CS1.
  8. 32k Memory Expansion supported.
  9. PIO and RS232 ports are supported, but using a different method than the original TI99/4a.
  10. Support for two external joysticks, or simulates one joystick input using numeric keypad.
  11. Runs over 200 cartridges correctly.  Cartridges that depend on non-implemented CRU bits or non-documented video chip operation will fail.  Other cartridges may fail due to bugs in the Win994a Simulator (major author apology).

  1. All TMS9940 CPU instructions are implemented.  CPU clock ticks are accumulated for both instructions and fast/slow memory accesses.  When enough clock ticks have been accumulated for 1/16 of a second real elapsed time, Win994a checks its high precision clock and gives up enough of the time slice so that accurate running time is maintained.
  2. Console based cassette tape functions for CS1 supported.
  3. Console ROM and multiple console GROM functionality implemented.
  4. Multiple peripheral based ROMs supported.
  5. Multiple cartridge based ROMs, GROMs, and RAM supported.
  6. TMS9918a: Uses DirectX for all operations.  Video modes GRAPHICS, TEXT, MULTICOLOR, BITMAP, and BITMAP-TEXT are implemented.  Sprites, sprite coincidence, screen blanking, and vertical interrupt operations are implemented.
  7. TMS9919: Uses DirectSound for all operations.  All three voices and noise channel supported.
  8. TMS5220: Speech synthesizer functions fully implemented. Speech text is displayed on a scrolling marquee in addition to being spoken.
  9. Disk Controller and three floppy drives fully supported.
  10. PIO and RS232 ports are supported, but using a different method than the original TI99/4a. PIO/1, PIO/2, RS232/1, RS232/2, RS232/3, and RS232/4 provide six separate pathways for making printouts through Window's print system. They do not provide input/output capabilities with the PC's actual hardware ports.
  11. Support for two externally connected joysticks, or simulates one joystick input using the keyboard numeric keypad.
Cartridge Selection

Demonstration Cart

What's New In Versoin 3.010:

Download Win994a:

Note- cart/disk/cassette images are available in their own sections as single downloads for those with slower connections.  For those with broadband, all of the images can be downloaded in single zip files from the main Win994a page.

New!  4/2/13
Win994a Simulator Download  - Version 3.010


Win994a is unsupported software, so a special help forum has been created:
Win994a Support Forum
Please post any questions or comments here and perhaps other users can provide some assistance.

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