diff --git a/ui/cmddb.c b/ui/cmddb.c
index 9c97eb4..79c1a75 100644
--- a/ui/cmddb.c
+++ b/ui/cmddb.c
@@ -301,6 +301,13 @@ const struct cmddb_record commands[] = {
 "    Remove an alias definition.\n"
 "alias <name> <command>\n"
 "    Define a new alias.\n"
+	},
+	{
+		.name = "fill",
+		.func = cmd_fill,
+		.help =
+"fill <address> <length> <b0> [b1 b2 ...]\n"
+"    Fill the given memory range with a repeated byte sequence.\n"
 	}
 };
 
diff --git a/ui/devcmd.c b/ui/devcmd.c
index ecf6ad2..76a27f5 100644
--- a/ui/devcmd.c
+++ b/ui/devcmd.c
@@ -753,3 +753,64 @@ int cmd_locka(char **arg)
 	printc("LOCKA is %s\n", (regval[0] & FCTL3_LOCKA) ? "set" : "clear");
 	return 0;
 }
+
+int cmd_fill(char **arg)
+{
+	char *addr_text = get_arg(arg);
+	char *len_text = get_arg(arg);
+	char *byte_text;
+	address_t addr = 0;
+	address_t len = 0;
+	uint8_t buf[256];
+	int period = 0;
+	int phase = 0;
+	int i;
+
+	if (!(addr_text && len_text)) {
+		printc_err("fill: address and length must be supplied\n");
+		return -1;
+	}
+
+	if (expr_eval(addr_text, &addr) < 0) {
+		printc_err("fill: invalid address\n");
+		return -1;
+	}
+
+	if (expr_eval(len_text, &len) < 0) {
+		printc_err("fill: invalid length\n");
+		return -1;
+	}
+
+	while ((byte_text = get_arg(arg))) {
+		if (period >= sizeof(buf)) {
+			printc_err("fill: maximum length exceeded\n");
+			return -1;
+		}
+
+		buf[period++] = strtoul(byte_text, NULL, 16);
+	}
+
+	if (!period) {
+		printc_err("fill: no pattern supplied\n");
+		return -1;
+	}
+
+	for (i = period; i < sizeof(buf); i++)
+		buf[i] = buf[i % period];
+
+	while (len > 0) {
+		int plen = sizeof(buf) - phase;
+
+		if (plen > len)
+			plen = len;
+
+		if (device_writemem(addr, buf + phase, plen) < 0)
+			return -1;
+
+		addr += plen;
+		len -= plen;
+		phase = (phase + plen) % period;
+	}
+
+	return 0;
+}
diff --git a/ui/devcmd.h b/ui/devcmd.h
index a0bd419..e37b4d7 100644
--- a/ui/devcmd.h
+++ b/ui/devcmd.h
@@ -39,5 +39,6 @@ int cmd_setwatch_w(char **arg);
 int cmd_delbreak(char **arg);
 int cmd_break(char **arg);
 int cmd_locka(char **arg);
+int cmd_fill(char **arg);
 
 #endif