Left Side: 'half' length, 240 character System 3000 cards
Right Side: 'third' length, 96 character System /3 cards
(image taken from here)
This half size 240 column card shows already all features of the later 96 column card (shown above on the right side):
The restriction to 96 characters on the other hand added a high compatibility layer with classic cards, as all handling coudl be kept fully compatible with 80 column cards.
How to encode 3 characters in 4 groups of 6 holes
Both cards used a modified EBCDIC code with full 8 bit encoding as seen here:
(Table taken from this incredible useful page)
- The holes are numbered
1248 ABCD. - Of these the lower 6 (1..B) are punched into every character cell
- The holes for CD of each character cell are combined into the top 6 hole group.
This seems to be a quite odd scheme until we consider that punch cards had as well writing along the top row(s). The first 64 character encoding (framed in blue) will have only no holes in C or D, thus leave the top area unharmed. By arranging all basic letters (only upper case), numbers and symbols within these 64 codes chances are high that most cards will have no hole within the upper fourth of the card. Perfect for undisturbed labeling. Isn't it?
This half size 240 column card shows already all features of the later 96 column card:
How to encode 3 characters in 4 groups of 6 holes
This half size 240 column card shows already all features of the later 96 column card (shown above on the right side):
The restriction to 96 characters on the other hand added a high compatibility layer with classic cards, as all handling coudl be kept fully compatible with 80 column cards.
How to encode 3 characters in 4 groups of 6 holes
Both cards used a modified EBCDIC code with full 8 bit encoding as seen here:
(Table taken from this incredible useful page)
- The holes are numbered
1248 ABCD. - Of these the lower 6 (1..B) are punched into every character cell
- The holes for CD of each character cell are combined into the top 6 hole group.
This seems to be a quite odd scheme until we consider that punch cards had as well writing along the top row(s). The first 64 character encoding (framed in blue) will have only no holes in C or D, thus leave the top area unharmed. By arranging all basic letters (only upper case), numbers and symbols within these 64 codes chances are high that most cards will have no hole within the upper fourth of the card. Perfect for undisturbed labeling. Isn't it?
Some History:
Before the System /3 there was the System 3000
The 96 column card (like the system /3) didn't appear out of nowhere but is based on the System 3000 design developed in Böblingen in the early 1960s. The System 3000 was intended as a very low end machine. It introduced an 240 column punch card half the size of the standard one, to be seen on the left side of this picture:
(image taken from here)
This half size 240 column card shows already all features of the later 96 column card:
- Encoding (see below) of three characters within a column
- as 4 groups of 6 holes
- three of them holding a character each
- the fourth combining two 'overflow' bits per character if needed
The system 3000 suffered from problems with its card devices (and possibly a certain 'not invented here' syndrome in Rochester).
Rebirth as 96 column card
While the System 3000 was cancelled in 1964 (?), the idea of a smaller, more capable punch card lived on. In fact, the System /3's 96 column card follows the System 3000'S card in all but mechanical definition. While being smaller, it had only 32 physical columns, spaced wider than the System 3000 card but at the same time with smaller holes. It's safe that this was to get around the mechanical problems that killed the System 3000.
How to encode 3 characters in 4 groups of 6 holes
*1 - As in 'real new super high tech 30% more efficient'
*1 - As in 'real new super high tech 30% more efficient'
Some History:
Before the System /3 there was the System 3000
The 96 column card (like the system /3) didn't appear out of nowhere but is based on the System 3000 design developed in Böblingen in the early 1960s. The System 3000 was intended as a very low end machine. It introduced an 240 column punch card half the size of the standard one, to be seen on the left side of this picture:
(image taken from here)
This half size 240 column card shows already all features of the later 96 column card:
- Encoding (see below) of three characters within a column
- as 4 groups of 6 holes
- three of them holding a character each
- the fourth combining two 'overflow' bits per character if needed
The system 3000 suffered from problems with its card devices (and possibly a certain 'not invented here' syndrome in Rochester).
Rebirth as 96 column card
While the System 3000 was cancelled in 1964 (?), the idea of a smaller, more capable punch card lived on. In fact, the System /3's 96 column card follows the System 3000'S card in all but mechanical definition. While being smaller, it had only 32 physical columns, spaced wider than the System 3000 card but at the same time with smaller holes. It's safe that this was to get around the mechanical problems that killed the System 3000.
How to encode 3 characters in 4 groups of 6 holes
*1 - As in 'real new super high tech 30% more efficient'