Hi, > [...] > > independently of the CPU's frequency). If the program > reads several times > Yes, 4 times.
Typical "delay" technique. If you disassemble the DOS program you will almost certainly see that it doesn't do anything with the values it reads from the port. :) It needs this delay because the reset signal (in the "reset" register, accessible by writing to 0x226) must be kept asserted for a minimum time of I don't remember how many microseconds, so games assert the reset signal, read a few times from the reset port to achieve the delay (4 to 6 consecutive reads), then deassert the reset line. > > Command 0xe2 was a pain to reverse-engineer. Are 0x06 and > 0x6b actual > > commands, or arguments to a command (e.g. 0xe2)? > Exactly, that were arguments to 0xe2:) Anyway, until 0xe2 is > unknown, this > Millenium game doesn't produce any sound under dosemu. > But atleast it doesn't lock now, when arguents are handled > "correctly", i.e. > known what is to ignore. Command 0xe2 is a sort of challenge/response command. Whatever value is output to this port modifies some internal (hidden) registers, and the contents of these registers (the response to the "challenge") is transferred into memory via DMA (!), one byte at a time. See the code I pointed to in the first message. I know at least one game (Wing Commander: Rebel Alliance) that locks if command 0xe2 is not implemented completely (it actually checks the data returned via DMA, and locks if it's not correct). > > Get a sound card! Or are you out of ISA/PCI slots? :) > Exactly, you guessed also this. How are you doing it?:) > Damn this engineers who put only 1 ISA (or even 0!) to the MB! I know... I only have one ISA slot on my mobo, but I'm keeping it for my LAPC1 card. :) > > There is a PC-speaker driver for Windows, but it is fully > synchronous (i.e. > I knew it was for win95 but never seen it for NT. I know I had it on my machine for a while before I got a soundcard (quite a while ago), and I'm pretty sure I was running NT4 at the time. :) But anyway the driver is worthless because it blocks the entire machine while it's playing. I wouldn't be surprised if someone wrote a Disney SoundSource (or "parallel-port soundblaster") driver for NT, some people really have nothing to do with their time. ;) Cheers, Vlad. - To unsubscribe from this list: send the line "unsubscribe linux-msdos" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
