The format depends on the program writing the tape, binary or text. In "Binary" tapes, the eight holes correspond to a "byte", which is just loaded into memory, byte-by-byte. The problem is that paper tape readers are error prone and any binary error was a potential crash. To solve this problem, the Altair Basic "Boot" loader starts with a straight binary tape. The straight binary formart continues for a few hundred bytes during which a "checksum loader" is read. Then a special binary code on the tape triggers a jump from the "boot loader" to the "checksum loader". You can recognize the blocks of the checksum loader on the tape, because every foot or two, you see a code that consistently repeats. Text format paper tapes are almost always simple, standard ASCII codes translated into binary. Text format can be recognized because, in those days, ASCII was almost always limited to 7-bits. This means that the tape has a column on one edge with very few holes -- that is the column 8. The other side is column 1. Here is a link to an excellent 7-bit ASCII table that I just found: http://www.neurophys.wisc.edu/www/comp/docs/ascii.html Here is a clip from it: Decimal Octal Hex Binary Value 065 101 041 01000001 A 066 102 042 01000010 B 067 103 043 01000011 C 068 104 044 01000100 D 069 105 045 01000101 E So with column 8 on the left, you read like this: (Holes in the tape translate to binary "1"s.) xOxxxxxO translates to 01000001 binary -- which is the octal 101 -- which is a capital "A". xOxxxOxO translates to 01000101 binary -- which is the octal 105 -- which is a capital "E". Most of us found "Octal" codes easiest to work with manually -- Hex became popular later. Got It ? -----Original Message----- From: Vintage Computer Festival [SMTP:vcf@vintage.org] Sent: Thursday, February 28, 2002 5:51 AM To: Classic Computers Mailing List Subject: Need paper tape encoding format Is there info somewhere that shows how symbols are encoded onto paper tape? Ideally it would include the actual hole positions like so: 8 4 2 1 A: * B: * C: * * (Note: this is not an actual example but just an example of the format I'm looking for. Of course.) Thanks! -- Sellam Ismail Vintage Computer Festival ------------------------------------------------------------------------------ International Man of Intrigue and Danger http://www.vintage.org * Old computing resources for business and academia at www.VintageTech.com *