OK, seems you've got it going now but during that time I tried "my version" of the formula with the following code:
Code:
PsuedoSeconds VAR WORD
Hours VAR WORD
Minutes VAR WORD

Start:
    HSEROUT["Program start",13,13]

    Minutes = 30
    Hours = 0
    GOSUB Calculate
    GOSUB PrintResult
    
    Minutes = 59
    Hours = 0
    GOSUB Calculate
    GOSUB PrintResult
    
    Minutes = 0
    Hours = 1
    GOSUB Calculate
    Gosub PrintResult
    
    Hours = 2
    Minutes = 15
    GOSUB Calculate
    Gosub PrintResult

    Hours = 3
    Minutes = 59
    GOSUB Calculate
    Gosub PrintResult
            
    Hours = 10
    Minutes = 0
    GOSUB Calculate
    Gosub PrintResult
    
    Pause 100
    
END

Calculate:
    PsuedoSeconds = (Hours * 3600 + Minutes * 60) / 255
RETURN

PrintResult:
    HSEROUT[DEC2 Hours, ":", DEC2 Minutes, " - ", DEC PsuedoSeconds,13]
RETURN
And it outputs:
Code:
Program start

00:30 - 7
00:59 - 13
01:00 - 14
02:15 - 31
03:59 - 56
10:00 - 141
Which seems correct to me.

/Henrik.