diff --git a/README.md b/README.md
index 7f57ab7..dc70429 100644
--- a/README.md
+++ b/README.md
@@ -194,6 +194,8 @@ ctrl-t ? to list the available key commands.
 [20:19:12.041]  ctrl-t t       Toggle line timestamp mode
 [20:19:12.041]  ctrl-t U       Toggle conversion to uppercase
 [20:19:12.041]  ctrl-t v       Show version
+[20:19:12.041]  ctrl-t x       Send file using the XMODEM protocol
+[20:19:12.041]  ctrl-t y       Send file using the YMODEM protocol
 [20:19:12.041]  ctrl-t ctrl-t  Send ctrl-t character
 ```
 
diff --git a/man/tio.1.in b/man/tio.1.in
index 6b75422..b9cdf1a 100644
--- a/man/tio.1.in
+++ b/man/tio.1.in
@@ -323,6 +323,10 @@ Toggle line timestamp mode
 Toggle conversion to uppercase on output
 .IP "\fBctrl-t v"
 Show version
+.IP "\fBctrl-t x"
+Send a file using the XMODEM protocol (prompts for file name)
+.IP "\fBctrl-t y"
+Send a file using the YMODEM protocol (prompts for file name)
 .IP "\fBctrl-t ctrl-t"
 Send ctrl-t character
 
diff --git a/src/meson.build b/src/meson.build
index cec9429..73af4c7 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -18,6 +18,7 @@ tio_sources = [
   'rs485.c',
   'timestamp.c',
   'alert.c'
+  'xymodem.c'
 ]
 
 tio_dep = [
diff --git a/src/misc.h b/src/misc.h
index 6fe5368..d9a8e2b 100644
--- a/src/misc.h
+++ b/src/misc.h
@@ -29,3 +29,6 @@ long string_to_long(char *string);
 int ctrl_key_code(unsigned char key);
 void alert_connect(void);
 void alert_disconnect(void);
+
+extern char key_hit;
+int xymodem_send(int sio, const char *filename, char mode);
diff --git a/src/tty.c b/src/tty.c
index d6a38ed..0f57d75 100644
--- a/src/tty.c
+++ b/src/tty.c
@@ -105,6 +105,8 @@
 #define KEY_T 0x74
 #define KEY_U 0x55
 #define KEY_V 0x76
+#define KEY_X 0x78
+#define KEY_Y 0x79
 #define KEY_Z 0x7a
 
 enum line_mode_t
@@ -133,6 +135,8 @@ bool map_i_nl_cr = false;
 bool map_i_cr_nl = false;
 bool map_ign_cr = false;
 
+char key_hit = 0xff;
+
 static struct termios tio, tio_old, stdout_new, stdout_old, stdin_new, stdin_old;
 static unsigned long rx_total = 0, tx_total = 0;
 static bool connected = false;
@@ -321,6 +325,14 @@ void *tty_stdin_input_thread(void *arg)
             // Process quit and flush key command
             for (int i = 0; i<byte_count; i++)
             {
+                // first do key hit check for xmodem abort
+                if (!key_hit) {
+                    key_hit = input_buffer[i];
+                    byte_count--;
+                    memcpy(input_buffer+i, input_buffer+i+1, byte_count-i);
+                    continue;
+                }
+
                 input_char = input_buffer[i];
 
                 if (previous_char == option.prefix_code)
@@ -472,6 +484,32 @@ static void toggle_line(const char *line_name, int mask, enum line_mode_t line_m
     }
 }
 
+#define MAX_LINE 100
+static char line[MAX_LINE];
+
+static int tio_readln(void)
+{
+    char *p = line;
+    
+    /* Read line, accept BS and DEL as rubout characters */
+    for (p = line ; p < &line[MAX_LINE-1]; ) {
+        if (read(pipefd[0], p, 1) > 0) {
+            if (*p == 0x08 || *p == 0x7f) {
+                if (p > line ) {
+                    write(STDOUT_FILENO, "\b \b", 3);
+                    p--;
+                }
+                continue;
+            }
+            write(STDOUT_FILENO, p, 1);
+            if (*p == '\r') break;
+            p++;
+        }
+    }
+    *p = 0;
+    return (p - line);
+}
+
 void handle_command_sequence(char input_char, char *output_char, bool *forward)
 {
     char unused_char;
@@ -562,7 +600,9 @@ void handle_command_sequence(char input_char, char *output_char, bool *forward)
                 tio_printf(" ctrl-%c t       Toggle line timestamp mode", option.prefix_key);
                 tio_printf(" ctrl-%c U       Toggle conversion to uppercase on output", option.prefix_key);
                 tio_printf(" ctrl-%c v       Show version", option.prefix_key);
-                tio_printf(" ctrl-%c ctrl-%c  Send ctrl-%c character", option.prefix_key, option.prefix_key, option.prefix_key);
+                tio_printf(" ctrl-%c x       Send file via Xmodem-1K", option.prefix_key);
+                tio_printf(" ctrl-%c y       Send file via Ymodem", option.prefix_key);
+                tio_printf(" ctrl-%c ctrl-%c Send ctrl-%c character", option.prefix_key, option.prefix_key, option.prefix_key);
                 break;
 
             case KEY_SHIFT_L:
@@ -721,6 +761,17 @@ void handle_command_sequence(char input_char, char *output_char, bool *forward)
                 tio_printf("tio v%s", VERSION);
                 break;
 
+            case KEY_X:
+            case KEY_Y:
+                tio_printf("Send file with %cMODEM", toupper(input_char));
+                tio_printf_raw("Enter file name: ");
+                if (tio_readln()) {
+                    tio_printf("Sending file '%s'", line);
+                    tio_printf("Press any key to abort transfer");
+                    tio_printf("%s", xymodem_send(fd, line, input_char) < 0 ? "Aborted" : "Done");
+                }
+                break;
+
             case KEY_Z:
                 tio_printf_array(random_array);
                 break;
diff --git a/src/xymodem.c b/src/xymodem.c
new file mode 100644
index 0000000..1dbeddc
--- /dev/null
+++ b/src/xymodem.c
@@ -0,0 +1,223 @@
+/*
+ * Minimalistic implementation of the xmodem-1k and ymodem sender protocol.
+ * https://en.wikipedia.org/wiki/XMODEM
+ * https://en.wikipedia.org/wiki/YMODEM
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later OR MIT-0
+ * 
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <termios.h>
+#include "misc.h"
+
+#define STX 0x02
+#define ACK 0x06
+#define NAK 0x15
+#define CAN 0x18
+#define EOT "\004"
+
+#define OK  0
+#define ERR (-1)
+
+#define min(a, b)       ((a) < (b) ? (a) : (b))
+
+struct xpacket {
+    uint8_t  type;
+    uint8_t  seq;
+    uint8_t  nseq;
+    uint8_t  data[1024];
+    uint8_t  crc_hi;
+    uint8_t  crc_lo;
+} __attribute__((packed));
+
+/* See https://en.wikipedia.org/wiki/Computation_of_cyclic_redundancy_checks */
+static uint16_t crc16(const uint8_t *data, uint16_t size)
+{
+    uint16_t crc, s;
+
+    for (crc = 0; size > 0; size--) {
+        s = *data++ ^ (crc >> 8);
+        s ^= (s >> 4);
+        crc = (crc << 8) ^ s ^ (s << 5) ^ (s << 12);
+    }
+    return crc;
+}
+
+static int xmodem(int sio, const void *data, size_t len, int seq)
+{
+    struct xpacket  packet;
+    const uint8_t  *buf = data;
+    char            resp = 0;
+    int             rc, crc;
+    
+    /* Drain pending characters from serial line. Insist on the
+     * last drained character being 'C'.
+     */
+    while(1) {
+        if (key_hit)
+            return -1;
+        if (read(sio, &resp, 1) < 0) {
+            if (errno == EWOULDBLOCK) {
+                if (resp == 'C') break;
+                if (resp == CAN) return ERR;
+                usleep(50000);
+                continue;
+            }
+            perror("Read sync from serial failed");
+            return ERR;
+        }
+    }
+
+    /* Always work with 1K packets */
+    packet.seq  = seq;
+    packet.type = STX; 
+
+    while (len) {
+        size_t  sz, z = 0;
+        char   *from, status;
+
+        /* Build next packet, pad with 0 to full seq */
+        z = min(len, sizeof(packet.data));
+        memcpy(packet.data, buf, z);
+        memset(packet.data + z, 0, sizeof(packet.data) - z);
+        crc = crc16(packet.data, sizeof(packet.data));
+        packet.crc_hi = crc >> 8;
+        packet.crc_lo = crc;
+        packet.nseq = 0xff - packet.seq;
+
+        /* Send packet */
+        from = (char *) &packet;
+        sz =  sizeof(packet);
+        while (sz) {
+            if (key_hit)
+                return ERR;
+            if ((rc = write(sio, from, sz)) < 0 ) {
+                if (errno ==  EWOULDBLOCK) {
+                    usleep(1000);
+                    continue;
+                }
+                perror("Write packet to serial failed");
+                return ERR;
+            }
+            from += rc;
+            sz   -= rc;
+        }
+        
+        /* 'lrzsz' does not ACK ymodem's fin packet */
+        if (seq == 0 && packet.data[0] == 0) resp = ACK;
+
+        /* Read receiver response, timeout 1 s */
+        for(int n=0; n < 20; n++) {
+            if (key_hit)
+                return ERR;
+            if (read(sio, &resp, 1) < 0) {
+                if (errno ==  EWOULDBLOCK) {
+                    usleep(50000);
+                    continue;
+                }
+                perror("Read ack/nak from serial failed");
+                return ERR;
+            }
+            break;
+        }
+        
+        /* Update "progress bar" */
+        switch (resp) {
+        case NAK: status = 'N'; break;
+        case ACK: status = '.'; break;
+        case 'C': status = 'C'; break;
+        case CAN: status = '!'; return ERR;
+        default:  status = '?';
+        }
+        write(STDOUT_FILENO, &status, 1);
+
+        /* Move to next block after ACK */
+        if (resp == ACK) {
+            packet.seq++;
+            len -= z;
+            buf += z;
+        }
+    }
+
+    /* Send EOT at 1 Hz until ACK or CAN received */
+    while (seq) {
+        if (key_hit)
+            return ERR;
+        if (write(sio, EOT, 1) < 0) {
+            perror("Write EOT to serial failed");
+            return ERR;
+        }
+        write(STDOUT_FILENO, "|", 1);
+        usleep(1000000); /* 1 s timeout*/
+        if (read(sio, &resp, 1) < 0) {
+            if (errno == EWOULDBLOCK) continue;
+            perror("Read from serial failed");
+            return ERR;
+        }
+        if (resp == ACK || resp == CAN) {
+            write(STDOUT_FILENO, "\r\n", 2);
+            return (resp == ACK) ? OK : ERR;
+        }
+    }
+    return 0; /* not reached */
+}
+
+int xymodem_send(int sio, const char *filename, char mode)
+{
+    size_t         len;
+    int            rc, fd;
+    struct stat    stat;
+    const uint8_t *buf;
+    
+    /* Open file, map into memory */
+    fd = open(filename, O_RDONLY);
+    if (fd < 0) {
+        perror("Could not open file");
+        return ERR;
+    }
+    fstat(fd, &stat);
+    len = stat.st_size;
+    buf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
+    if (!buf) {
+        close(fd);
+        perror("Could not mmap file");
+        return ERR;
+    }
+
+    /* Do transfer */
+    key_hit = 0;
+    if (mode == 'x') {
+        rc = xmodem(sio, buf, len, 1);
+    }
+    else {
+        /* Ymodem: hdr + file + fin */
+        while(1) {
+            char hdr[128], *p;
+            p  = stpcpy(hdr, filename) + 1;
+            p += sprintf(p, "%ld %lo %o", len, stat.st_mtime, stat.st_mode);
+
+            rc = -1;
+            if (xmodem(sio, hdr, p - hdr, 0) < 0) break; /* hdr with metadata */
+            if (xmodem(sio, buf, len,     1) < 0) break; /* xmodem file */
+            if (xmodem(sio, "",  1,       0) < 0) break; /* empty hdr = fin */
+            rc = 0;                               break;
+        }
+    }
+    key_hit = 0xff;
+    
+    /* Flush serial and release resources */
+    tcflush(sio, TCIOFLUSH);
+    munmap((void *)buf, len);
+    close(fd);
+    return rc;
+}