add Circuitous font notes

res/notes/font.txt

@@ -0,0 +1,148 @@
+CIRCUITOUS font information
+2019-07 last updated
+
+- $80 characters only (high bit is always 0)
+- $20 and above are standard ASCII
+- $00..$1F are various shapes and characters in no standard order
+
+Font routines are near the top of LC RAM, accessible to either bank. However,
+font data is stored in LC RAM bank 2, because that's where we have space.
+Note that most strings are in LC RAM bank 1, which is admittedly inconvenient.
+You are responsible for copying characters to a place where the drawing routine
+can access them. (See src/ui.font.a) The drawing routines will switch to LC 2
+to access font data, then back to LC 1 before returning.
+
+Font data is stored non-consecutively. Row 0 data starts at $D600, in order,
+so row 0 of character $00 is at $D600, row 0 of character $01 is at $D601, &c.
+Row 1 starts at $D680; row 2 starts at $D700. The entire font set finishes at
+$D9FF.
+
+HEX  DESCRIPTION
+$00  full horizontal circuit path
+$01  horizontal circuit path endpoint with rounded left side
+$02  horizontal circuit path endpoint with rounded right side
+$03  full vertical circuit path
+$04  vertical circuit path endpoint with rounded top
+$05  vertical circuit path endpoint with rounded bottom
+$06  rounded top-left quadrant circuit path
+$07  rounded top-right quadrant circuit path
+$08  rounded bottom-left quadrant circuit path
+$09  rounded bottom-right quadrant circuit path
+$0A
+$0B  right arrow
+$0C
+$0D
+$0E
+$0F  times
+$10  dot, small
+$11  dot, medium
+$12  dot, large
+$13  dot, extra large
+$14
+$15
+$16
+$17
+$18
+$19
+$1A
+$1B  lowercase a with umlaut
+$1C  lowercase e with accent
+$1D  lowercase i with accent
+$1E  lowercase o with backtick accent
+$1F  uppercase A with accent
+$20  space
+$21  !
+$22  "
+$23  #
+$24  $
+$25  %
+$26  &
+$27  '
+$28  (
+$29  )
+$2A  *
+$2B  +
+$2C  ,
+$2D  -
+$2E  .
+$2F  /
+$30  0
+$31  1
+$32  2
+$33  3
+$34  4
+$35  5
+$36  6
+$37  7
+$38  8
+$39  9
+$3A  :
+$3B  ;
+$3C  <
+$3D  =
+$3E  >
+$3F  ?
+$40  @
+$41  A
+$42  B
+$43  C
+$44  D
+$45  E
+$46  F
+$47  G
+$48  H
+$49  I
+$4A  J
+$4B  K
+$4C  L
+$4D  M
+$4E  N
+$4F  O
+$50  P
+$51  Q
+$52  R
+$53  S
+$54  T
+$55  U
+$56  V
+$57  W
+$58  X
+$59  Y
+$5A  Z
+$5B  [
+$5C  \
+$5D  ]
+$5E  ^
+$5F  _
+$60  `
+$61  a
+$62  b
+$63  c
+$64  d
+$65  e
+$66  f
+$67  g
+$68  h
+$69  i
+$6A  j
+$6B  k
+$6C  l
+$6D  m
+$6E  n
+$6F  o
+$70  p
+$71  q
+$72  r
+$73  s
+$74  t
+$75  u
+$76  v
+$77  w
+$78  x
+$79  y
+$7A  z
+$7B  {
+$7C  |
+$7D  }
+$7E  ~
+$7F  full block (solid cursor)