Tentatively implemented the vertical scrolling part of EGA and (S)VGA CRTC register 8;

PCap devices list generator now aborts if WinPcap is not present;
Fixed the CD-ROM START STOP UNIT command;
More preparations for SCSI removable hard disks.

src/net_pcap.c

@@ -220,6 +220,7 @@ int
 network_devlist(netdev_t *list)
 {
     char errbuf[PCAP_ERRBUF_SIZE];
+    char *temp_dev;
     pcap_if_t *devlist, *dev;
     int i = 0;
 
@@ -228,6 +229,14 @@ network_devlist(netdev_t *list)
     strcpy(list->description, "None");
     list++; i++;
 
+    /* See if WinPcap is even present, and get out of here if it's not. */
+    temp_dev = (char *)pcap_lib_version();
+    if (temp_dev == NULL) {
+	/* Hmm, WinPcap doesn't seem to be alive.. */
+	pclog("PCAP: WinPcap library not found, not processing the networks list further!\n");
+	return(i);
+    }
+
     /* Retrieve the device list from the local machine */
     if (pcap_findalldevs(&devlist, errbuf) == -1) {
 	pclog("NETWORK: error in pcap_findalldevs: %s\n", errbuf);