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[Vanshilar]

I have the original version of JetFighter by Velocity Development (1988). This game isn't on Abandonia yet, I was submitting it. However, when using Dosbox, the game hangs after the title screen (it does not run in Win XP directly). The helpfile that came with the game says this:

Q: I have the right equipment and enough memory, but the
program won't load after the title screen.

A: You may have a mixed or 'impure' version of DOS on your
machine. DOS consists of three files: COMMAND.COM and two
hidden files. If these files are not from the SAME VERSION
of DOS, JetFighter may not run. This case usually occurs if
the store set up your hard disk.

Try starting the computer ('booting') from an ORIGINAL DOS
diskette. Your computer should have come with a version of
DOS on diskette. Put the DOS disk in your A: drive, turn off
the computer, and then turn it on again. Now try running
JetFighter. If it works, you have a problem with the DOS on
your hard disk. Keep in mind, however, that you may not
experience any trouble with other software. JetFighter
simply needs to use ALL the resources of your computer.

What I gather then is that 1) I need a "pure" version of DOS to get it to run and 2) even back in 1988, it was somewhat finicky to get to run. However, I used to be able to run it fine on my old computer many years ago, so I know it works.

Anyhow, does anyone have any recommendations as to how to get Dosbox (or any other program) to emulate a pure DOS? Or maybe know what global variables need to be set that those three files did. Any help would be appreciated.

P.S. I've uploaded the game to Abandonia if anyone wants to take a crack at it.

[Eagle of Fire]

Did you try to switch your core to normal?

[Japo]

That about DOS versions isn't very applicable to DOSBox, and besides this game is problematic to run even in real DOS, reportedly impossible in non ancient processors. It's currenty not supported by DOSBox.

http://www.dosbox.com/comp_list.php?showID=2792
http://vogons.zetafleet.com/viewtopic.php?t=12963

[Vanshilar]

YES! The game seems to work by using the special build from the vogons.zetafleet.com thread (cvsbuild65_pq.rar) and setting "core=prefetch" in the dosbox.conf file. Those Vogons are pretty smart, huh. Thanks for figuring it out!

So apparently the manual was wrong, it does seem like JetFighter used some special "prefetch queue" stuff, that was particular to the 80386 and earlier processors -- maybe they didn't know the real reason back then and customer service decided to blame those bad hard drive installs.

Incidentally, the thread mentions copy-protection, but I would think another aspect is that the game uses a lot of different executables to run; there are 13 executables, and as far as I can tell, only 3 other (necessary) files. So maybe they used those prefetch files to keep all the executables working together.

Okay, time to start playing through the game again...:thumbs:

[Japo]

I haven't tried this game, but the new version of DOSBox (0.73) includes new options, I think this should work with "cputype=386_prefetch"