Leo paper tapes

The tapes have been converted to byte streams with each 7-bit character represented as a single byte. These have been interpreted according to the Leo III character code, which is summarised below. Interpretations of the tapes are here.

There is a program ptdecode.c which attempts to interpret the tapes as instructions. As usual, a Windows binary can be found here but read the caveat. Instructions are in a comment at the head of the source text.

To download any of the images of the tapes, just use a right mouse click and save as.

About half of the tapes are for loading in a naked machine with a procedure called “paper tape start”. Although we can run them in our emulator, most just loop indefinitely, obviously waiting for some kind of operator input. More investigation is needed along with a better emulation of the operator interaction.

Here is analysis of the only example of Leo III source code among the collection.

There was also a hand-written note.
Here are images of the handwriting on the tapes.

Index of LEO III tapes held as tape images size title in bytes as hand-written on the start of each tape 2,560  01037 772  01037-3 1,371  Bindec 5,558  Oips 8,474  Snips 2,128  Startfri 3,946  T69-1-5n 4,060  T69-1-6n 5,936  T69-1-6s 6,932  T998 3,952  U13-4-4s 319  U199 7,311  U199-1-1 3,434  U205s 6,326  U23load 6,397  U23start 900  U7notsta 3,077  U7start 4,870  U9005-2 5,024  U9005-3 22,266  U98-1-2s

Alpha numeric character codes   0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 0 sp 1 - 2 & 3 0 4   1 2 3 4 5 6 7 8 9 10 11 + : . £ 5   A B C D E F G H I = * ' ? (1) (2) 6   J K L M N O P Q R (3) % > < ½ \ 7   / S T U V W X Y Z ( ) , ; (5) (6) sp Space (1) Line End (2) Doubtful Block Mark (3) Right Arrow (5) Block End (6) Erase Paper tape character codes   Binary value of holes 1 to 4 on tape 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Binary value of holes 6 & 7 0 sp 1 2 3 4 5 6 7 8 9 10 11 + : . £ 1 - A B C D E F G H I = * ' ? (1) (2) 2 & J K L M N O P Q R (3) % > < ½ \ 3 0 / S T U V W X Y Z ( ) , ; (5) (6)