The Inner Workings Of; Unique Modes - Epson FX-80 User Manual

The inner workings of the Master Select
Some serious users may want to know in detail how Table 5-1 is
derived. This section is for them! Everyone else skip to "Unique
modes."
As mentioned above, each mode used by the Master Select com-
mand corresponds to one of the computer's bits. These bits have the
decimal values shown in Table 5-2.
Table 5·2. Master Select Bits, Codes, and Modes
Bit Decimal Mode
Number Code Name
1 1 Elite
2 2
-
3 4 Compressed
4 8 Emphasized
5 16
Double-Strike
6
32
Expanded
7
64
-
8
128
-
Each of these five modes is activated when its corresponding bit
(shown above) is on, otherwise it is inactive. For example, adding the
decimal codes 16 and 1 combines Double-Strike and Elite. Therefore
the sequence (ESC)"! "CHR$(17) prints that combination. Because
the decimal code 2 (bit 2) is not used, adding it to the sequence has no
effect. The same holds true with 64 and 128.
The addition of any of the three unused codes to the valid codes
simply adds a new number to the mode without changing the mode.
Bits and their corresponding values are covered in Chapter 11.
Unique modes
As you can see from Table 5-1, not every number between
0
and
255 evokes a unique print mode combination. In fact, close inspection
of the chart reveals only 16 unique varieties. How? Well, the left col-
umn names the 6 available densities
(3
pitches and
3
weights). The top
row names 4 print qualities. Multiplying 4 times 6 gives us 24 possible
combinations. Eight of those, however, involve a conflict of modes-
that is, one mode takes precedence over another. That reduces the
number of unique modes to 16, half of which are Single-Strike.
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