Computer ◆ Conservation ◆ Society

Software & Emulators

This area of the CCS website is, at the time of writing, very much a “work in progress”. It is intended to replace the web pages on our FTP site at but, in time, it may overlap with some or all of the material at

One of the many activities of the Computer Conservation Society is to develop preserve software for historic computers, many of which have long since passed into oblivion. In order to make this activity meaningful and to allow for the possibility of writing new programs for dead computers it is sometimes necessary and always useful to implement emulators : programs which run within modern computers but which interpret programs written for the target machine and cause them to be executed in much the same way as the hardware of the original computers once interpreted the instructions of their programs and carried out those instructions.

Some of the computers listed here still exist as “preserved” machines and some as “replicas” while others may have long since passed into oblivion. All, however, may be of interest.

So this is our collection of software and emulators - our “zoo” if you like. Created so that old computers, many now gone beyond recall, and their software may live again on your desktop. Enjoy!

Each of the computers listed here has its own web page which can be reached using links on this page.

Each machine’s web page lists one or more emulators/other related material and a dowload button or a link to the developers’ website whence dowloads may be effected. Clicking the thumbnails to the right will bring up an illustration of the software in use.

Important notes on some emulators

Some of the emulators listed in this section were written in the 1990s for Microsoft DOS. In the intervening years MS Windows has developed to the point where it is unable to support these 16-bit applications without the use of special techniques. DOSBox is a freeware program which can overcome these limitations. Here is a guide to using DOSBox with these emulators.

In the lists of emulators which you may find from the links on this web page, some will be endorsed with the symbol 64 and some with 32. The former indicates that the downloaded program requires the use of DOSBox to run in all 64-bit versions of Windows, The latter indicates that the program needs DOSBox to run in 32-bit versions. All other DOS programs can be invoked from the command line.

In summary, the DOS-based emulators all need DOSBox if they are to run within 64-bit versions of Windows but will run unassisted in 32-bit versions unless they invoke fullscreen mode.

In addition to the above, at least one Windows-based emulator is unable to run under 64-bit versions of Windows. It too is endorsed 64. In this case we have no workaround.

Manchester “Baby” or Small Scale Experimental Machine

The first electronic stored-program computer ever, the “Manchester Baby” was built at the University of Manchester in 1948. A replica of this machine is regularly demonstrated by CCS members at the Museum of Science and Industry (MSI) in Manchester.

Three emulators are available for the SSEM which can be found here.


EDSAC was built at the University of Cambridge and was the first stored-program computer to provide a useful service. A replica of EDSAC is currently being built at The National Museum of Computing at Bletchley.

Two emulators are available for the EDSAC which can be found here.

Ferranti Sirius

The Sirius computer was designed in the late 1950s making its first appearance in 1959. It was Ferranti’s first computer to use transistors rather than valves (vacuum tubes). It ran cool enough to be used in a normal office environment, standing behind an office desk.

Although not especially fast, it could be slowed down even further for demonstration and educational purposes. It had decimal displays and could be programmed in Ferranti’s autocode language. It was described as “a truly general purpose machine suitable for a wide variety of uses in industry, commerce, science and technical education”. About 20 systems were delivered by 1963 and it did find application in all of those fields.

There are three known survivors. Two, thought to have been in working order when retired, are in storage: one owned by Museum Victoria, Melbourne, Australia and the other by the London Science Museum. The third is a fine, though non-working, exhibit on display in the computer museum of Monash University, Melbourne, Australia.

An emulator is available for the Sirius which can be found here.

Ferranti Pegasus

Developed by Ferranti in the mid-1950s, Pegasus was the first British computer to be made in significant quantities (for the time). Highly regarded for its reliability, some 40 machines were constructed. Two Pegasii survive, both belonging to the Science Museum Group, one in London and one in Manchester. For some years in the 2000s the London machine was run on a regular basis by CCS volunteers. Sadly it has now been removed from display and put into storage. The Manchester machine is also thought to be about to be stored but was in any case, not working.

An emulator is available for Pegasus which can be found here.

Elliott 903

A small-sized transistor computer of the mid-1960s manufactured by Elliott Automation in Borehamwood in the UK. About 1,000 Elliott 903s were made sold mainly for industrial and military applications.

A number of Elliott 903s are known still to exist, some in private hands. One 903 is regularly demonstrated at the National Museum of Computing in Bletchley another at the Centre for Computing History at Cambridge.

An emulator is available for the 903 which can be found here.

Stantec Zebra

Designed in the Netherlands and produced by STC in the UK in the late 1950s, the Stantec Zebra was a small valve-based computer which enjoyed limited success but which has some interesting and ingenious characteristics.

One surviving Zebra is known in Delft.

Two versions of an emulator are available for the Zebra which can be found here.

ICT 1900

Designed in Canada and developed in the UK, the ICT (later ICL) 1900 Series sold in substantial quantities from 1964 onwards. A number of 1900s are known to survive, but none in working order. An ICL 2966 running 1900 order code under emulations is under restoration at the national Museum of Computing (TNMoC) at Bletchley Park. Various 1900 emulators are available which can be found from here.

Manchester University/Ferranti Atlas 1

Developed by Manchester University and manufactured by Ferranti, Atlas 1 was, for a brief while in the early 1960s, the fastest computer in the world. Atlas 1 introduced numerous innovations, most famously the now almost universal system of store paging. Three Atlas 1s (and three Atlas 2s) were made. A huge amount of material about Atlas is available here and here.

Large parts of an Atlas 1 are in storage at the National Museums of Scotland but restoration is thought to be impractical.

Two emulators are available for Atlas 1 which can be found here.

Manchester University MU5

Developed by Manchester University with manufacturing help from ICL in the period 1966-74 MU5 was built as a means of researching advanced computer design. With a performance of roughly 20 Atlas Powers (to use the then popular measure) one of its main design objectives was to support high-level programming languages with an order code which compilers could use most effectively.

Although the design was not replicated, it was a major influence on ICL’s 2900 Series (1974) and its VME sucessors which sold in their thousands and are still available today, more than 40 years on.

MU5 was decommissioned in 1982. No substantial MU5 hardware has survived but a few parts were retained for display by the University.

One emulator is available for MU5 which can be found here.

English Electric KDF9

The KDF9 computer was a mid-1960s product of the English Electric company intended to be a sucessor to the NPL-derived Deuce. A mid-range (by the standards of the day) scientific machine it was very cost-effective. Around 30 of them were sold.

The last KDF9 is believed to have still been in use at NPL in 1980. None are thought to have survived.

Two emulators are available for the KDF9 together with much original software which can be found which can be found here.


In 1949, the J. Lyons company, caterers, decided they needed a computer, but, finding that none were (yet) on sale, decided to build their own. Thus LEO (Lyons Electronic Office) was born and was the first computer in the world to undertake commercial data processing. The initial design was replicated and sold to a few other organisations as LEO II. Finally LEO III came to market in 1961. A LEO III emulator and a substantial collection of original software is available here.

etc. etc.