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If you are looking for information on the ICL 1900 series
mainframe computer, I hope that the information contained
on this site will satisfy you, whether it is just idle
curiosity or a technical question that you want answered.
This series of mainframes was in use from the mid-1960s to the
mid-1980s and under emulation (2900/DME) into the 1990s in the UK,
and the GEORGE 3 Operating System was being used on one site in
St. Petersburg, Russia until 2010/2011 under CME/G3.
In addition to 1900 series information, there is also some information
on other (ICT/ICL and earlier) systems available, see the
Technical Publications Index.
If you have any further information or corrections, to
what I have written, please email me:
bill@icl1900.co.uk
*** WANTED ***
Whilst we have a considerable amount of information about the
hardware and software of the 1900 range, there are several
'gaping holes' in our knowledge, any help in filling in those
gaps would be greatly appreciated. Currently the most obvious
areas where we have little or no information are (in no
particular order):
| Item |
What's wanted |
| 1906 and 1907 |
Anything regarding the actual hardware architecture. Whilst
it appears as a 1905 with EBM and 22AM added (I
think
that it used the same logic cards as the 1904/5 and the 1904E/F
series) and we know that the store data path was 48 bits
wide (like the 1906A/S). That is the limit of our knowledge.
|
| 1906A and 1906S |
Similar to the previous 'big beasts' our
knowledge of these machines is also almost totally lacking. |
|
Executives |
Anything regarding the
specifications and internals of E3RM, E6BM. Any
information regarding the executives for the Stevenage 1900
processors (1901, 1902, 1903, 1901A, 1902A and 1903A). |
| Paging |
We have some information
regarding paging hardware but the only program that
we can currently run on the 1904S CPU in paged mode is FLIT
(A CPU test/diagnostic program). Ideally a copy of a GEORGE
4 install tape, as that would allow us to complete the pager
hardware and also complete the suite of 1900 GEORGE
Operating systems. |
| Images |
Any pictures of 1900 system
components. One item of particular interest is the
engineers' 'light map'. This panel inside one of the CPU
doors presented that state of approximately 1000 signals. In
the case of a system halt, these light would become static
and operators were requested to fill in a paper sheet
showing the state of the lights. A legible picture of there
sheets would be useful to add some extra realism, |
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The Art-Deco Gilfillan Building in Delamere Avenue
Nairobi, Kenya (ca. 1963)
The headquarters of ICT (East Africa) Ltd
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