Conference 501clb::pcdoom

    I think I can safely say this is nothing to do with DOOM, but the
    computer's fault.
    
    If it really is switching from 8 to 25 Mhz (the display changing is not
    definite... I mean, it could be a loose connection) then this would
    explain momentary jerkiness, switching to smooth(er) action when at 25.
    
    If you have no L2 cache, DOOM will run slower (as will anything), but
    it shouldn't crash. This also would not explain the change in speed
    settings - it would *always* be jerky, not switching between two
    speeds.
    
    Sounds to me like your machine is very sick. Maybe the L2 chips, if in
    the machine, are faulty. This would explain the jerkiness and also the
    crashing, but it doesn't explain the speed display changing.... I think
    maybe this is something else - a dodgy connector, a bad jumper or, at
    worse, something seriously wrong with your chip or clock!
    
    Good luck, this certainly isn't DOOM's fault...
    
    Dan

    Oops. Looks like terminology has given the wrong impression.
    
    When the display kicks down to 8MHz, there's an appreciable speed
    change, too, but that's not the same. By "jerky" I mean the same sort
    of effect as looking at an AVI file played with a low-spec machine:
    there appear to be frames left out just to keep up.
    
    I don't think that DOOM is at fault, either, since the same kit loaded
    onto a DECpc 425i works perfectly. However, I'm convinced that there's
    no loose wires (famous last words) so I can't for the life of me work
    out what IS wrong. Hence this note.
    
    By the way. The reason why I'm asking here is that DOOM is the only
    piece of software I've used that goes wrong - so far. If I can find out
    why my machine does what it does with this game, I might be able to
    work out what's wrong with it.
    
    You never know, my machine may simply be allergic to DOOM and/or the
    mindless violence!!  :-) :-)
    
    David.

    I can see two problems :
    
    i) The speed switching
    
    ii) DOOM crashing
    
    The speed switching shouldn't cause DOOM to crash (if that's all it is
    - a switch from the two different processor speeds).
    
    The two, I think, can be handled separately.
    
    
    i) No-one's pressing the TURBO switch, or CTRL-ALT-keypad+, or
    CTRL-ALT-keypad- are they?
    
       Loose connection / dodgy switch (okay, maybe not then)
    
       More techy problem (ask the IBMPC-95 guys) like something to do with
       the processor, the system clock chip, or a speed jumper on the M/B.
    
    
    ii) Just DOOM? Have you tried any other games along the ilk - maybe
    anything that uses the DOS Extender, such as Rise of the Triad, DOOM
    ][, Heretic, Descent ?
    
    	The crash could be something to do with memory, be it L2 or your
    SIMMs, or even the on-chip 8k of L1 cache I suppose!
    
    	More likely, however, is some hardware clash. IRQ settings? What
    video card, sound card, network card, etc. do you have fitted?
    
    Cheers,
    Dan

    
    The frequency display on the front of the case is set by jumpers - and
    does not reflect the true speed of your processor if it should
    change... (Or a least thats what I have heard) 
    
    I wouldn`t take the fact that the display changes to mean for definite
    that your cpu frequency is changing as well....
    
    Nick.

    The LED processor speed is connected to the turbo switch.  The LEDs
    themselves do not indicate what speed the machine is running at, but
    what the makers of the PC expect it to run at for both positions of the
    turbo switch.  (This knowledge comes from building PCs for a small
    company and setting the LEDs for the speeds they would run at.)
    
    so it is quite possible that something is causing the switch in the
    LED.  Is there a noticeable difference in speed when it changes?
    
    Does the LED display change at the same point each time or at various
    different points?
    
    What are you loading in autoexec.bat and config.sys?
    
    Mark

    There *IS* a speed change (for the worse) when the display changes. Or,
    you could say, the display changes as a result of the speed drop. Take
    your pick.
    
    I'm not concerned what the actual speed shows (although I'd like it to
    show something nearer 100!) but the fact that it changes from "turbo"
    to "non-turbo" is the worrying part for me.
    
    The speed change/freeze/crash happens at any point and there is rarely
    any rhyme or reason.
    
    I've already posted my startup files in IBMPC-95 and I'll repost here
    if you wish, but because I only have 4mb, I have to run with a bare
    boot anyway, so there aren't any TSRs or anything loaded.
    
    David.

    Some BIOS have a hot key or 3 keys for switching the speed, do u know
    what it is on your PC?
    
    Also try Doom 1.9, you never know, it may fix something, however 1.9 is
    slower than 1.2!!
    
    BTW Do you have a soundcard?

    Yes, Greg, I do have a soundcard. It's just an early 8 bit V1.5
    SoundBlaster. It worked perfectly in my previous PC. Do you think this
    might be a cause? I'll try whipping it out, but I hope that's not the
    problem!
    
    David.

    I'd try taking it out, you never know
    
    My standard way of fixing things is remove everything, back to the most
    basic system you have. Then add things in one by one.