Character codes in use with EDSAC. I found these to be confusing when I started working on the EDSAC replica. The First two columns show the codes used on paper tape. There was no way of distinguishing letters from digits! You can write P instead of 0 and EDSAC cannot tell the difference. The actual holes in the paper tape are given in the column labelled Binary except that the first bit is inverted. Blank tape therefore gives 10000, and erase (all five holes punched) gives 01111. The Printer codes are more conventional, with LS and FS being letter shift and figure shift, CR and LF being carriage return and line feed, and SP being the space character. For inputs to either simulator (Elsie or Martin's) use only letters and digits. The layout and greek characters use the ASCII substitutes as shown in the right hand column. Space, Newline can be used to make tape files more legible and are ignored. Tape codes Printer Binary Ascii substitute ls fs ls fs P 0 P 0 00000 Q 1 Q 1 00001 W 2 W 2 00010 E 3 E 3 00011 R 4 R 4 00100 T 5 T 5 00101 Y 6 Y 6 00110 U 7 U 7 00111 I 8 I 8 01000 O 9 O 9 01001 J J 01010 pi FS 01011 # S S " 01100 Z Z + 01101 K K ( 01110 Erase LS 01111 * Blank 10000 . F F $ 10001 theta CR 10010 @ D D ; 10011 phi SP 10100 ! H H � 10101 N N , 10110 M M . 10111 delta LF 11000 & L L ) 11001 X X / 11010 G G # 11011 A A - 11100 B B ? 11101 C C : 11110 V V = 11111