diff --git a/avail.sh b/avail.sh
new file mode 100755
index 0000000..aafeb75
--- /dev/null
+++ b/avail.sh
@@ -0,0 +1,246 @@
+#!/bin/bash
+
+[[ -e ${HOME}/.bashtools/bashtools.sh ]] && . ${HOME}/.bashtools/bashtools.sh
+if [[ -n $HAVE_BASHTOOLS ]]; then
+    print1="csecho"
+    print2="inform"
+else
+    print1="echo"
+    print2="echo"
+fi
+
+function usage() {
+    echo "usage:  $0 [-n] mode v1 [v2] ... [v3]"
+    echo
+    echo "   -n:   plaintext mode, no ansi colours"
+    echo
+    echo "Valid modes:"
+    echo "    s = systems in series"
+    echo "        v1 = system1 availability%"
+    echo "        v2 = system1 availability%"
+    echo "        ..."
+    echo "    p = systems in parallel"
+    echo "        v1 = one system's availability%"
+    echo "        v2 = number of systems"
+    echo "    i = individual system"
+    echo "        v1 = mtbr (mean time between failures)"
+    echo "        v2 = mttr (mean time to repair)"
+    echo ""
+}
+
+function line() {
+    local len fmt out
+    len=$1
+    cmd="printf %0.s- {1..${len}}"
+    out=$(bash -c "$cmd")
+    echo "$out"
+}
+
+
+if [[ $1 == "-n" ]]; then
+    HAVE_BASHTOOLS=""
+    shift
+fi
+
+mode=$1
+shift
+
+if [[ $mode == "s" ]]; then
+    if [[ $# -lt 1 ]]; then
+        error "usage:  $0 s sys1uptime sys2uptime ... sysXuptime"
+        exit 1
+    fi
+    diagram="[client]\n"
+    diagram="${diagram}   |\n"
+    diagram="${diagram}[^b${1}%^p uptime]\n"
+    eq="(${1}/100)"
+    shift
+    while [[ $# -ge 1 ]]; do
+        diagram="${diagram}   |\n"
+        diagram="${diagram}[^b${1}%^p uptime]\n"
+        eq="${eq} * (${1}/100)"
+        shift
+    done
+    diagram="${diagram}   |\n"
+    diagram="${diagram}[server]\n"
+    eq="${eq} * 100"
+    answer=$(echo "scale=9; $eq" | bc)
+    answershort=$(echo "$answer" | tr -dc '9.')
+    nines=$(echo $answershort | tr -d -C 9 | wc -c | tr -d ' ')
+    [[ $nines -eq 1 ]] && ess="" || ess="s"
+    ninestext="${nines} nine${ess}"
+
+
+    if [[ -n $HAVE_BASHTOOLS ]]; then
+        csecho -e "$WHITE" "^b${UNDERLINE}Architecture^p\n"
+        csecho "$GREEN" "${diagram}"
+        echo
+        csecho -e "$WHITE" "^b${UNDERLINE}Availability^p\n"
+        inform "^bEquation:^p     ${eq}"
+        inform "^bAvailability:^p ${answershort}% (^b\"$ninestext\"^p)"
+        echo
+    else
+        echo "Architecture"
+        echo "------------"
+        diagram=$(echo "$diagram" | sed 's/\^.//g')
+        echo -e "${diagram}"
+        echo
+        echo "Availability"
+        echo "------------"
+        echo "* Equation:     ${eq}"
+        echo "* Availability: ${answershort}% (\"$ninestext\")"
+        echo
+    fi
+elif [[ $mode == "p" ]]; then
+    if [[ $# -ne 2 ]]; then
+        error "usage:  $0 s sysuptime nsystems"
+        exit 1
+    fi
+    sysuptime=${1}
+    shift
+    nsites=${1}
+    shift
+
+    text="[${sysuptime}% uptime]"
+    textansi="[^b${sysuptime}%^p uptime]"
+    len=${#text}
+    biglen=$(( $len * $nsites ))
+    biglen=$(echo "$biglen + ($nsites * 3)" | bc)
+
+    len=$((len + 3))
+
+    if [[ $((len % 2)) -eq 0 ]]; then
+        s1=$(( $len / 2 ))
+        s2=$(( $s1 - 1 ))
+        linktext=$(printf "%${s1}s|%${s2}s" " " " ")
+    else
+        s1=$(( $len / 2 ))
+        linktext=$(printf "%${s1}s|%${s1}s" " " " ")
+    fi
+
+    diagram="$(line $biglen)"
+    diagram="${diagram}\n"
+    if [[ $((biglen % 2)) -eq 0 ]]; then
+        s1=$(( $biglen / 2 ))
+        s2=$(( $s1 - 1 ))
+        upd=$(printf "[%${s1}s%${s2}s]" "client")
+    else
+        s1=$(( $biglen / 2 ))
+        upd=$(printf "[%${s1}s%${s1}s]" "client")
+    fi
+    diagram="${diagram}${upd}"
+    diagram="${diagram}\n"
+    diagram="${diagram}$(line $biglen)"
+    diagram="${diagram}\n"
+    # intentially skip element 0
+    for ((i=0;i<nsites;i++)); do
+        diagram="${diagram}${linktext}"
+    done
+    diagram="${diagram}\n"
+
+    sysline="$(line ${#text})"
+    syslines="${sysline}"
+    for ((i=1;i<nsites;i++)); do
+        syslines="${syslines}    ${sysline}"
+    done
+    diagram="${diagram}${syslines}\n"
+
+
+    diagram="${diagram}${textansi}"
+    # intentially skip element 0
+    for ((i=1;i<nsites;i++)); do
+        diagram="${diagram}    ${textansi}"
+    done
+    diagram="${diagram}\n"
+    diagram="${diagram}${syslines}\n"
+
+    # intentially skip element 0
+    for ((i=0;i<nsites;i++)); do
+        diagram="${diagram}${linktext}"
+    done
+    diagram="${diagram}\n"
+
+    if [[ $((biglen % 2)) -eq 0 ]]; then
+        s1=$(( $biglen / 2 ))
+        s2=$(( $s1 - 1 ))
+        upd=$(printf "[%${s1}s%${s2}s]" "server")
+    else
+        s1=$(( $biglen / 2 ))
+        upd=$(printf "[%${s1}s%${s1}s]" "server")
+    fi
+
+    diagram="${diagram}$(line $biglen)"
+    diagram="${diagram}\n"
+    diagram="${diagram}${upd}\n"
+    diagram="${diagram}$(line $biglen)"
+    diagram="${diagram}\n"
+
+
+    eq="(1 - (1 - (${sysuptime}/100))^${nsites})*100"
+    answer=$(echo "scale=15; $eq" | bc)
+    answershort=$(echo "$answer" | tr -dc '9.')
+    nines=$(echo $answershort | tr -d -C 9 | wc -c | tr -d ' ')
+    [[ $nines -eq 1 ]] && ess="" || ess="s"
+    ninestext="${nines} nine${ess}"
+
+
+    if [[ -n $HAVE_BASHTOOLS ]]; then
+        csecho -e "$WHITE" "^b${UNDERLINE}Architecture^p\n"
+        csecho "$GREEN" "${diagram}"
+        echo
+        csecho -e "$WHITE" "^b${UNDERLINE}Availability^p\n"
+        inform "^bEquation:^p     ${eq}"
+        inform "^bAvailability:^p ${answershort}% (^b\"$ninestext\"^p)"
+    else
+        echo "Architecture"
+        echo "------------"
+        diagram=$(echo "$diagram" | sed 's/\^.//g')
+        echo -e "${diagram}"
+        echo
+        echo "Availability"
+        echo "------------"
+        echo "Equation:     ${eq}"
+        echo "Availability: ${answershort}% (\"$ninestext\")"
+    fi
+    echo
+elif [[ $mode == "i" ]]; then
+    if [[ $# -ne 2 ]]; then
+        error "usage:  $0 i mtbf mttr"
+        exit 1
+    fi
+    mtbf=${1}
+    shift
+    mttr=${1}
+    shift
+
+    eq="${mtbf} / (${mtbf} + ${mttr}) * 100"
+    answer=$(echo "scale=15; $eq" | bc)
+    answershort=$(echo "$answer" | sed 's/0\+$//')
+
+    if [[ -n $HAVE_BASHTOOLS ]]; then
+        csecho -e "$WHITE" "^b${UNDERLINE}Availability^p\n"
+        inform "^bMean Time Between Failures:^p  ${mtbf} hours"
+        inform "^bMean Time to Repair:^p         ${mttr} hours"
+        inform "^bEquation:^p                    ${eq}"
+        inform "^bAvailability:^p                $GREEN$BOLD${answershort}%^p"
+    else
+        echo "Availability"
+        echo "------------"
+        echo "Mean Time Between Failures:  ${mtbf} hours"
+        echo "Mean Time to Repair:         ${mttr} hours"
+        echo "Equation:                    ${eq}"
+        echo "Availability:                ${answershort}%"
+    fi
+    echo
+else
+    if [[ -n $HAVE_BASHTOOLS ]]; then
+        error "invalid mode."
+    else
+        echo "ERROR: invalid mode."
+    fi
+    usage
+    exit 1
+fi
+
+
+