To converting to IEEE floating point here are two Tcl procedures to convert to and from a MIL-STD-1750A 32-bit floating number. The procedure '''1750afloat''' take a integer value (1750a) and returns the floating point representation.  The procedure '''float1750a''' take a floating point number and returns the integer representation of the 1750a value
 if {0} {
  1750A floating point numbers are representd as a fractional 
  mantissa times 2 rasied to the power of the exponent.  
  The 32-bit format is:
    MSB                                   LSB
    smmm mmmm mmmm mmmm mmmm mmmm seee eeee
    0                                     31
 } 

 proc 1750afloat {32BitInt_1750a} {
    if {![string is integer $32BitInt_1750a]} {
        return "invalid input: \"$32BitInt_1750a\" not a integer"
    }
    set mantissa [expr {$32BitInt >> 8}]
    set exponent [expr {$32BitInt & 0xff}]
    if {[expr {$exponent & 0x80}] != 0} {
        set exponent [expr {int($exponent - 256)}]
    }
    set fnd_float [expr {$mantissa * pow(2, $exponent - 23)}]
    return $fnd_float
 }

 proc float1750a {floatnum} {
    if {![string is double $floatnum]} {
        return "invalid input: \"$floatnum\" not a double"
    }
    if {$floatnum == 0} {
        set 32BitInt_1750a 0
    } else {
        set exponent [expr {int(ceil(log(abs($floatnum)) / log(2.)))}]
        set mantissa [expr {round($floatnum / pow(2, $exponent - 23))}]
        #boundary condition check and repair at 0x800000
        if {$mantissa == 8388608} {
            set mantissa [expr {$mantissa / 2}]
            incr exponent
        }
        set 32BitInt_1750a [expr {($mantissa << 8) | ($exponent & 0xff)}]
    }
    return $32BitInt_1750a
 }

# examples per MIL-STD-1750A section 4.1.5
 format %X [float1750a [expr .9999999 * pow(2,127)]] ;#7FFFFF7F
 format %X [float1750a [expr .5 * pow(2,127)]] ;#4000007F
 format %X [float1750a [expr .625 * pow(2,4)]] ;#50000004
 format %X [float1750a [expr .5 * pow(2,1)]] ;#40000001
 format %X [float1750a [expr .5 * pow(2,0)]] ;#40000000
 format %X [float1750a [expr .5 * pow(2,-1)]] ;#400000FF
 format %X [float1750a [expr .5 * pow(2,-128)]] ;#40000080
 format %X [float1750a [expr .0 * pow(2,0)]] ;#0
 format %X [float1750a [expr -1.0 * pow(2,0)]] ;#80000000
 format %X [float1750a [expr -.5000001 * pow(2,-128)]] ;#BFFFFF80
 format %X [float1750a [expr -.7500001 * pow(2,4)]] ;#9FFFFF04

# wrap test of the procedures
 1750afloat [float1750a 1.222332] ;#1.22233200073

[Michael Jacobson] ~ jakeforce@home.com