45

From what I read, most line printers have 132 columns. Also, the VT-220 and presumably other terminals may be switched between 80 columns (that's a usual width) and 132 columns.

As I recall, 80 columns was because of those Fortran punch cards.

But what's special about 132? It's hardly more than 128, which has the advantage of being a power of 2.

60

As so often with basic measurements like this, the roots have been laid out way before today's computers, even before computers (non human that is) at all.

From what I read, most line printers have 132 columns. Also, the VT-220 and presumably other terminals may be switched between 80 columns (that's a usual width) and 132 columns.

The number is a result of the paper originally used for tabulating machines and a common font size at some later point. In this case it's 14 inch wide paper and a 10 characters per inch printing, which resulted in 132 characters per line - the remaining 8 character positions are omitted for the transport tractor feed pin holes.

But what's special about 132? It's hardly more than 128, which has the advantage of being a power of 2.

As being developed way before the binary computer, powers of two are not related in any way.


In Detail:

It's about the paper.

It begins with tabulating typewriters. Most notably they carry a quite wide carriage able to hold paper of 22 or sometimes more inches wide. Classic (pre-computer *1) ledger sheet size (in the US *2,3) is 22 inches wide (*4). To place tabulating machines into accounting business, similar forms had to be used.

Long story short(*5), the result was support for 10 characters per inch and 6 or 8 lines per inch, and a two paper formats based on a 'half ledger' of 11 inch:

  • 8.5 x 11 inch with 80 characters per line and 66/88 lines per page
  • 14 x 11 inch with 132 characters per line and 66/88 Lines per page

plus a (later) 'condensed' format of

  • 14 x 8.5 inch with 132 characters and 66 lines per page (only 8 lines per inch)

When computers came along, their printers were not only built using the same components as tabulating printers, but more importantly had to adhere to these paper formats to be useful.

Minis (as the mentioned VT terminals) and micros just carried it on - again to make their output useful to the businesses they where meant to be sold to.


*1 - Classic as in genuine handwritten thread-bound ledger books.

*2 - Jup, that's the sheet size where the ledger page size comes from.

*3 - European pre-DIN formats were similar, which opens the interesting notion that the printing press was already setting international standards way before any standardization organization. Just not as systematic.

*4 - Or better most used was 17" x 22". Other common ledger sizes are, 17" x 28", 19" x 24", 24" x 38"

*5 - There was much variation of character density and capability among early machines. For example a IBM 405 only handled 8 character per inch and a total of 88 print bars (positions). At least it could also print letters, where the earlier 285 could only handle numbers.

  • 1
    I made some simple (hopefully not controversial) edits. A few more comments (no time for a full answer): "standard" US paper sizes for single sheets are 8.5"x11" (letter) and 8.5"x14" (legal). So the typical line printer 14"x11" would match one dimension of each "standard" size, making for easier filing. The other common sizes are multiples - 17" x 22" = 4x 8.5" x 11", 17" x 28" = 4x 8.5" x 14", etc. Interesting anecdote: TTY43 (the first terminal I owned, and a far cry from the TTY33) used 8.5" x 11" landscape mode fanfold paper to get "traditional" 66x132 in letter format. – manassehkatz Oct 3 '18 at 14:35
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    Footnote number 3: "The IBM 405 only handled 88 character per inch" – Wilson Oct 3 '18 at 14:38
  • @Wilson I noticed that too, but didn't change it in the edit because I am not sure what the correct number is. – manassehkatz Oct 3 '18 at 15:07
  • @Wilson Following the link for the 405 I added will tell that it had 88 bars. With bar printers this also is the number of characters in a line (like the number of hammers define it for chain or drum printers). These where spaced as 8 per inch - not mentioned there, you may need to belive me (or search fo more sources :)) – Raffzahn Oct 3 '18 at 15:35
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    10 characters-per-inch and 12 characters-per-inch were such common type sizes that they had names: "pica" and "elite". The combination of character size and page size yields the number of columns you can fit on the page. – Ken Gober Oct 3 '18 at 16:53
13

The United States has its own paper sizes, two of which are 11"x17" ('ledger/tabloid') and 8.5"x11" ('letter'), which are similar to A3 and A4 and have the same sort of predominance.

Early fixed-width font printers usually offered a 12 characters-per-inch typeface.

12*11 = 132; so 132 characters is the number you can fit on a landscape 'letter' page, or a portrait 'ledger' page.

  • 3
    Sorry, not realy, that's a bit of a hindsight based explanation :) Early printers, for which tehse formats where defined, where at most 10 characters per inch (usually only 8). 12 cpi didn't show up until the late 30s – Raffzahn Oct 3 '18 at 14:25
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    I'm not sure I buy hindsight as disqualifying an answer as to the appearance of a convention. Hindsight is what creates conventions: if I have the hindsight that every other printer previously released supports 132-column output, I'll make sure mine does too. That doesn't mean your objection is wrong on its other points though. – Tommy Oct 3 '18 at 14:26
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    Except, the 132 column printers didn't apear until way after the format was defined. Without puting your printer down, I feel safe that it's a reather new model, way after the standard seting ones of the 1910/20s - which only did 88 charcters on 11 inch wide paper. – Raffzahn Oct 3 '18 at 14:32
  • @Raffzahn that's not an except that's "your objection ... on its other points". – Tommy Oct 3 '18 at 14:39
  • Somehow you lost me on that... – Raffzahn Oct 4 '18 at 0:51
5

132 column printers were a defacto standard decades before it became common to print on sheet-fed A-size (8.5x11 inch) paper, let alone in sheet-fed in landscape orientation, so an explanation based on 12 CPI and 11-inch long paper in landscape orientation certain is not the origin of the 132-colum standard.

For example, most models of the IBM type 1403 printer, one of the most common high-speed printers in the 1960s and 1970s, had a tractor feed mechanism intended for a paper width 14 7/8 inches, and printed at 10 characters per inch horizontally, spanning 13.2 inches of the paper width, leaving a little less than 7/8 inch margin on both sides, which included the tractor feed holes. There were individual print hammers for each character position, so the character pitch could not be changed, though the number of lines per inch vertically could.

It's possible that the IBM 1403 printer was the main device that popularized 132-column printing on 14 7/8 inch wide paper. Certainly IBM's competitors did their best to copy it. IBM's earlier accounting machines might have used the same paper size, but they didn't print 132 columns. Some of them had a much smaller number of fixed-position columns. The 407 accounting machine, contemporary with the 1403 printer, used 120 columns.

  • :)) New machines are, more often than not, made to run ith their predecessors 'fuel'. Aren't they :)) – Raffzahn Nov 16 '18 at 0:34
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    Printers for the ICL 1900 range of computers (UK, 1960s - 1970s) typically had 120 columns, though there was at least one printer with a 132-column option. – another-dave Nov 16 '18 at 1:07
  • If I remember correctly, the ICL 132-column printers were train printers. The 120-column ones were line printers. – cup Nov 16 '18 at 6:50
  • I agree with this answer; the 1403 printer (introduced in 1959 for the 1401 computer) is the first I could find using 132 columns. (Although it also came in 100 and 120 column models.) But this still leaves the question of why the 1403 printer used 132 columns. – Ken Shirriff Jan 7 at 1:56

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