Document Title: REVISION HISTORY ---------------- VERSION 1. I'd like to contribute something to the cause. The original 6502 emulator that I used in EMU (which has long since been retired) is attached to this email message. I don't know where I got it originally, but I tweaked it to run faster than the original. It's here so people can get a good start or see what's going on in emulation. Please include the following stipulations in your FAQ if you decide to put it in there: * I am not the original author of the code. I got it from somewhere off the net, and remember reading that it was OK to distribute. If someone knows who the original author is, please email me or include it. I made some modifications to it. * I did some quickie optimizations on it * EMU Does not use any of this code * It's nowhere near optimized 100% * Memory reads don't use the get6502memory call (made it lots faster - 3X) * put6502memory could be rewritten as a macro to increase speed * CPU Modes could be rewritten as macros to prevent a call dereference * There are some problems in the BCD emulation in the ABC/SBC instructions All in all, it runs at about 2.5-3MHZ emulated on a 486/100 when all stack probes are removed. This code was my starting block when I began coding the Asteroids emulator back in February. I hope people find this useful. This code will run Asteroids & Asteroids Deluxe unmodified. The vector generator part isn't included... Anything else I can add to the FAQ to assist? Let me know! -->Neil VERSION 2. Version 1 came in the form of a text file. This version is in the form of a .c and a .h file. Any occurances of >> (C bit shift operator) in version 1 were corrupt and converted to a single > (greater than comparison). This is now fixed. When exec6502() is called the number of machine cycles to execute is now passed as opposed to the number of instructions. This should make interrupt timing more accurate.