CAT(5)CAT(5)NAMEcat - C/A/T phototypesetter code
DESCRIPTION
The Graphic Systems C/A/T phototypesetter is driven by
sending it a sequence of one-byte codes which specify
characters, fonts, sizes, and other control information.
The C/A/T's basic unit of length is 1/432 of an inch
(about 6 units to a typesetter's ``point''). The quantum
of horizontal motion is one unit. The quantum of vertical
motion is three units (1/144 of an inch, 1/2 point).
The top two bits of the code classify it as one of three
major types: an escape code (top bit 1), a flash code (top
bits 00), or a control code (top bits 01). A code of all
zeros is ignored; a code of all ones is illegal.
A flash code specifies flashing one of 63 characters, as
given by the remaining six bits. Since this is not enough
to specify all possible characters, or even all characters
in a single font -- there are 108 per font -- various con-
trol codes (described later) select a font and either the
Lower or Upper half of the font. The Lower half is the
first 63 characters of the font; the Upper half is the
remaining 45. A flash code of 46 or higher in the Upper
half is illegal.
An escape code specifies horizontal motion. The size of
the motion, in horizontal quanta, is the one's-complement
of the low seven bits of the code. The direction of the
motion is set by control codes. Hitting the right or left
margin limit switch is illegal and will cause the machine
to stop. The machine starts out, after initialization,
hard against the left margin limit switch; an initial
escape of 16 units must be given before starting work, and
the position after this motion should be the limit of all
future leftward motions. From this point, the distance to
the right margin limit switch is about 7.5 inches.
A code with the top three bits 011 is a lead code, speci-
fying vertical motion. The remaining five bits are the
one's-complement of the size of the motion, in vertical
quanta. The direction of motion is set by control codes.
The amount of vertical motion is, in principle, limited
only by running off the paper in the upward direction and
by the limited capacity of the output cartridge in the
downward direction.
A code with the top four bits 0101 is a size-change code,
which specifies movement of the lens turret and the dou-
bler lens to change point size. These codes are as fol-
lows:
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Size Code
6 01011000
7 01010000
8 01010001
9 01010111
10 01010010
11 01010011
12 01010100
14 01010101
16 01011001
18 01010110
20 01011010
22 01011011
24 01011100
28 01011101
36 01011110
Size changes involving the doubler lens alter the horizon-
tal position. Changes from single to double sizes should
be followed by a forward escape of 55 quanta; changes
from double to single sizes should be followed by a
reverse escape of 55 quanta. The single sizes are 6, 7,
8, 9, 10, 11, 12, 14, and 18; the double sizes are 16, 20,
22, 24, 28, and 36.
The control codes with the top four bits 0100 specify mis-
cellaneous control codes, not all of which have valid
meanings. They are:
initialize 01000000
stop 01001001
upper rail 01000010
lower rail 01000001
upper mag 01000011
lower mag 01000100
tilt up 01001110
tilt down 01001111
upper font half 01000110
lower font half 01000101
escape forward 01000111
escape backward 01001000
lead forward 01001010
lead backward 01001100
software cut 01001011
The initialize code causes leftward motion to the left
margin limit switch, and sets the following modes: escape
forward, lead forward, lower font half, lower rail, lower
mag, tilt down. Note that the left margin limit switch
does not define a precise position, and hence reinitializ-
ing the machine will destroy precise left-margin align-
ment.
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The stop code stops the machine, which must be manually
restarted (normally after changing output cartridges);
this code should be used only at the end of a run.
Fonts are selected by the combination of rail, mag, and
tilt. The tilt codes do not exist on the 4-font C/A/T;
this is the only user-visible difference between the
4-font and 8-font machines. The correspondence between
rail/mag/tilt and font number is as follows:
rail mag tilt 4font 8font
lower lower up 1 1
lower lower down 1 2
upper lower up 2 3
upper lower down 2 4
lower upper up 3 5
lower upper down 3 6
upper upper up 4 7
upper upper down 4 8
The software cut code should not be issued to the hard-
ware, but is used by some spooling software to indicate
places where it is legal for the spooler to break output
between pages. This code should be followed by an ini-
tialize code.
A complete C/A/T file should begin with an initialize code
followed by an escape-16 code, and should end with 14
inches of trailer and a stop code.
HISTORY
The software cut code is a local invention. This manual
page written at U of T by Henry Spencer.
BUGS
The documentation and the hardware disagree on the initial
tilt setting; the above describes the hardware.
While the hardware is obsolete, this man page is provided
to document the format for historical and/or compatibility
purposes.
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