diff --git a/main.go b/main.go
index 4b6ed33..f79e3a1 100644
--- a/main.go
+++ b/main.go
@@ -20,7 +20,7 @@ import (
 
 const (
 	intro = PROGNAME + ` -- Expressions calculator ` + VERSION + `
-	Based on the Expr package ` + EXPR_VERSION + `
+	Based on the Expr package ` + EXPR_VERSION + ` (` + EXPR_DATE + `) 
 	Type help to get the list of available commands
 	See also https://git.portale-stac.it/go-pkg/expr/src/branch/main/README.adoc
 `
@@ -243,7 +243,8 @@ func isReaderTerminal(r io.Reader) bool {
 
 func registerLocalFunctions(ctx expr.ExprContext) {
 	const (
-		devParamProp = "prop"
+		devParamProp   = "prop"
+		devParamDigits = "digits"
 	)
 
 	aboutFunc := func(ctx expr.ExprContext, name string, args map[string]any) (result any, err error) {
@@ -300,6 +301,46 @@ func registerLocalFunctions(ctx expr.ExprContext) {
 		return
 	}
 
+	binFunc := func(ctx expr.ExprContext, name string, args map[string]any) (result any, err error) {
+		var value, digits int64
+		var ok bool
+		var sb strings.Builder
+
+		if value, ok = args[expr.ParamValue].(int64); !ok {
+			err = expr.ErrExpectedGot(name, expr.TypeInt, args[expr.ParamValue])
+			return
+		}
+		if digits, ok = args[devParamDigits].(int64); !ok {
+			err = expr.ErrExpectedGot(name, expr.TypeInt, args[devParamDigits])
+			return
+		}
+		if digits != 64 && digits != 32 && digits != 16 && digits != 8 {
+			err = fmt.Errorf("%s param allows 8, 16, 32, or 64 values only", devParamDigits)
+			return
+		}
+
+		mask := uint64(0)
+		for i := 0; i < int(digits); i++ {
+			mask |= (1 << i)
+		}
+		maskedValue := uint64(value) & mask
+		// if maskedValue != uint64(value) {
+		// 	err = fmt.Errorf("%s param (%d) is not compatible with the value (%d) of %s param", expr.ParamValue, value, digits, devParamDigits)
+		// 	return
+		// }
+
+		for i := int(digits) - 1; i >= 0; i-- {
+			if maskedValue&(1<<i) == 0 {
+				sb.WriteByte('0')
+			} else {
+				sb.WriteByte('1')
+			}
+		}
+
+		result = sb.String()
+		return
+	}
+
 	ctx.RegisterFunc("about", expr.NewGolangFunctor(aboutFunc), expr.TypeString, []expr.ExprFuncParam{})
 	ctx.RegisterFunc("ctrlList", expr.NewGolangFunctor(ctrlListFunc), expr.TypeListOfStrings, []expr.ExprFuncParam{})
 	ctx.RegisterFunc("ctrl", expr.NewGolangFunctor(ctrlFunc), expr.TypeAny, []expr.ExprFuncParam{
@@ -314,6 +355,10 @@ func registerLocalFunctions(ctx expr.ExprContext) {
 		expr.NewFuncParam(expr.ParamName),
 	})
 
+	ctx.RegisterFunc("bin", expr.NewGolangFunctor(binFunc), expr.TypeInt, []expr.ExprFuncParam{
+		expr.NewFuncParam(expr.ParamValue),
+		expr.NewFuncParamFlagDef(devParamDigits, expr.PfOptional|expr.PfDefault, int64(8)),
+	})
 }
 
 func main() {