Atari ST series Technical Reference Manual page 51

XBIOS Device and System Functions
quite possible that these two clocks will not be set to the
same time. The new (blitter) ROMs, however, set the GEM­
DOS clock from the hardware clock at the termination of
every process.
Keyboard Vector Tables
The console device uses three sets of tables to tell it what
ASCII character to return when it receives a certain key code
from the IKBD device. One table has the ASCII values for
unshifted keys, one has the ASCII values for keys pressed
while holding down either Shift key, and one has the ASCII
values for keys pressed while the CapsLock is in effect. Each
table is 128 bytes long. Since there are only 104 keys on the
ST keyboard, a number of the values in the tables are not
used. The tables are arranged by key scan code. Since no key
has a scan code value of 0, the first entry in the table is 0.
Next comes the Esc key, which has a value of 1, followed by
the 1 key which has a value of 2. The scan code for each key
can be found in Appendix J, which shows all of the extended
keyboard codes. The identifier is the first byte of the two-
byte keycode value. For easier reference, a map of scan code
values is given in Figure 3-1.
Figure 3-1. Map of Scan Code Values
$61 $82 883 SB4 $03 $66 887 $88 809 SBft 88B 8BC SBD 829 $8 E
$BFj$10|«ll|si2|613|$14[#15|$16]ei7j618jS19|$lft|SlB
SID $1E S1F $28 821 $22 $23 $24 $25 $26 $27 $28
$2<* $2C $2D S2E $2F $38 $31 832 $33 $34 $35 _$36
$3 8
The TOS ROMs contain the default tables ordinarily
used to map keys to their ASCII values. It is possible, how­
ever, to substitute a RAM table for one or more of these key
maps. This allows you to change your keyboard layout to an
alternate configuration, such as that used for Dvorak key­
boards. An alternate key map may also be used to allow easy
access to certain foreign characters or math symbols. The
$3 9 $3A
862 $61
$53
$1£_ 82B
$66
$4ft
S4E
S6F
$71
43