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- Nintendo Entertainment System in Assembler
- version 0.17 (Beta)
-
- -------------------------------------------------------------------------------
-
- IMPORTANT: This version of NESA uses a tweaked video mode which may not work
- on all systems and could cause big problems with older cards & monitors.
- Please feedback on how well this works.
-
- Here is the latest beta version of my Nintendo NES Emulator for DOS. It is
- written in assembler and is freeware. The only limitation is that it
- must not be sold. I still retain copyright, of course.
-
- It is 25k long and will run at a reasonable speed on most PCs. I have some
- ideas for speeding it up a bit that aren't implemented yet.
-
- Minimum required spec is probably 386SX-40/486SX-25,640k RAM,VGA
-
- It supports Marat Fayzullin's NES cartridge format.
-
- Image Types :-
-
- Type 0 - most work (except for problems with 4017 writes !)
- Type 1 - some work. Metroid seems ok but Zelda starts then dies !
- Type 2 - Implemented. Seems to work ok.
- Type 3 - VROM Switch (most of the larger PASOFAMI types) implemented ok.
- (problems with some 8 x 16 sprites)
-
- If a file won't work, check the following...
-
- (1) The mirroring is correct. If its the wrong way round, some carts are
- very wierd - lots of zeros,crashes etc.
- (2) The file is ok. Try another copy - check the cartridge size is a
- multiple of 8192 + 16
-
- Command Line
- ============
-
- nesa -h<n> -b<n> -e<n> -m<n> -s -t<n> -o<n> -q <cartridge>.nes
-
- -h <n> Set # cycles for visible part of horizontal line (60)
- -b <n> Set # cycles for vblank part of horizontal line (16)
- -e <n> Set last scan line before VSYNC (256)
- -m <n> Set redraw rate. Can now be any value (3)
- -s Disable screen splitting. (off)
- -t <n> Display next 200 scanlines from line <n>. Displays a 200 line
- section of the screen,starting from scanline <n>. (off)
- -o <n> Scroll override. You will notice that some screens are split in that
- the score doesn't move when the game does - e.g. Mario. Try -o<n> if
- the scrolling is in the wrong place where <n> is the scan line to
- split .. 8-224 (off)
- -q toggle cartridges stated mirror
-
- These values can be changed if a game runs too slowly. Try setting -m7 first
- then reducing h,b and e experimentally ! If these values are set too low then
- some games will not work.
-
- Keys
- ====
-
- A Space
- B Left Alt Key (or Z)
- Select TAB
- Start Enter
- Move Arrow keys
-
- Release 0.1 (Alpha) 10-Sep-96
- First release.
-
- Relese 0.11 (Beta) 11-Sep-96
- Fixed bug - not updating z byte register correctly on PLP,RTI
- Fixed bug - code in RAM didn't work,usually causing BRK.
- Lots more games work now.
- Runs a fair bit quicker.
-
- Release 0.12 (Beta) 11-Sep-96
- Implemented 8x16 sprites,not sure if they work !!!
- Sprites behind background (Mario goes down pipes properly !)
- Screen split code written. Partially works
- Z as alternate key to Left Alt (Alt+Space in Win95,requested)
- Start drawing from position rather than miss lines out (requested).
- Supports multiple VROM Banks
-
- Release 0.13 (Beta) 12-Sep-96
- Supports SOME type 1 carts (very erratic !)
- Supports type 2 carts (reasonably well)
- Has battery backed RAM (which isn't yet,sorry)
- Scroll line position override.
-
- Release 0.15 (Beta) 30-Sep-96
-
- Screen Skip Counter can be any value
- Fixed sprite positioning problem (1 scan line down !)
- Added support for the hit flag ?
-
- Release 0.16 (Beta) 03-Oct-96
-
- Fixed the palette.
-
- Release 0.17 (Beta) 11-Oct-96
-
- 256x224 Screen.
-
- Missing from this version .... :-
-
- Player 2 Controls
- Support for PC Joystick
- Sound
- Support for PAL Cartridges (anyone have any ?)
- Backup the battery backed up memory.
- Improve support for .NES type 1 carts
-
- Thanks to :-
- Marat Fayzullin for the NES architecture document on which this
- emulator was largely based.
- ChaosKnight and Robert Schmidt (tweak) for help with the
- unusual video mode.
- -------------------------------------------------------------------------------
- Paul Robson
- autismuk@aol.com
-