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The ICL 1900 series computer uses a 6-bit character, giving
a 64 character set, which consists of the letters A-Z
(uppercase only), the numerals 0-9, a further 27 printable
symbols and a space character.
A fairly standard modification to this set was to replace
the ! on the print barrel with ½, as we (in the UK)
still used half-pennies back then.
Internal 64-Character Set
Least
Significant
3 bits |
Most Significant 3 bits of 6-bit Character |
| 0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
| 0 |
0 |
8 |
SPACE |
( |
@ |
H |
P |
X |
| 1 |
1 |
9 |
! |
) |
A |
I |
Q |
Y |
| 2 |
2 |
: |
" |
* |
B |
J |
R |
Z |
| 3 |
3 |
; |
# |
+ |
C |
K |
S |
[ |
| 4 |
4 |
< |
£ |
, |
D |
L |
T |
$ |
| 5 |
5 |
= |
% |
- |
E |
M |
U |
] |
| 6 |
6 |
> |
& |
. |
F |
N |
V |
↑ |
| 7 |
7 |
? |
' |
/ |
G |
O |
W |
← |
64-Character Card Code
| Symbol |
Card
Punching |
Symbol |
Card
Punching |
Symbol |
Card
Punching |
Symbol |
Card
Punching |
| |
|
& |
10 |
- |
11 |
|
|
| 0 |
0 |
& |
10/0 |
" |
11/0 |
|
|
| 1 |
1 |
A |
10/1 |
J |
11/1 |
/ |
0/1 |
| 2 |
2 |
B |
10/2 |
K |
11/2 |
S |
0/2 |
| 3 |
3 |
C |
10/3 |
L |
11/3 |
T |
0/3 |
| 4 |
4 |
D |
10/4 |
M |
11/4 |
U |
0/4 |
| 5 |
5 |
E |
10/5 |
N |
11/5 |
V |
0/5 |
| 6 |
6 |
F |
10/6 |
O |
11/6 |
W |
0/6 |
| 7 |
7 |
G |
10/7 |
P |
11/7 |
X |
0/7 |
| 8 |
8 |
H |
10/8 |
Q |
11/8 |
Y |
0/8 |
| 9 |
9 |
I |
10/9 |
R |
11/9 |
Z |
0/9 |
| |
|
+ |
10/2/8 |
[ |
11/2/8 |
£ |
0/2/8 |
| # |
3/8 |
. |
10/3/8 |
$ |
11/3/8 |
, |
0/3/8 |
| @ |
4/8 |
; |
10/4/8 |
* |
11/4/8 |
% |
0/4/8 |
| ( |
5/8 |
: |
10/5/8 |
> |
11/5/8 |
? |
0/5/8 |
| ) |
6/8 |
' |
10/6/8 |
< |
11/6/8 |
= |
0/6/8 |
| ] |
7/8 |
! |
10/7/8 |
↑ |
11/7/8 |
← |
0/7/8 |
Paper Tape Code
The 8-track paper tape code employs 7 data bits (standard
ISO 7-bit code) plus even parity, with the minor
exceptions:-
ISO £ has been replaced by #
ISO $ has been replaced by £
ISO _ (underline) has been replaced
by ←
Codes permitted for national use have
been used for $ and _ (underline).
Internally 3 shift characters are used to extend the
standard 64 character set to the full 128 characters
available on paper tape. The three internal characters used
as shift characters are:-
$ - octal #74 - alpha (α)
] - octal #75 - beta (β)
↑ - octal #76 - delta (δ)
The alpha and beta shift characters are only used when there
is a change of shift, whilst the delta shift character only
applies to the following character.
Alpha shift is basically the standard 64 character set.
Beta shift is a lower case version of the standard 64
character set.
Delta shift is the shift codes, transmission control codes
and the 7 characters not covered by alpha or beta shift.
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