Wilhelm Schickard (1592-1635), of Tuebingen, Wuerttemberg (now in Germany), made a "Calculating Clock". This mechanical machine was capable of adding and subtracting up to 6 digit numbers, and warned of an overflow by ringing a bell. Operations were carried out by wheels, and a complete revolution of the units wheel incremented the tens wheel in much the same way counters on old cassette deck worked.

The machine and plans were lost and forgotten in the war that was going on, then rediscovered in 1935, only to be lost in war again, and then finally rediscovered in 1956 by the same man (Franz Hammer)! The machine was reconstructed in 1960, and found to be workable. Schickard was a friend of the astronomer Johannes Kepler since they met in the winter of 1617.

Babbage designs an improved, simpler difference engine, a project which took 2 years. The machine could operate on 7th-order differences and 31-digit numbers, but nobody is interested in paying to have it built.

(In 1989-91, however, a team at London's Science Museum will do just that. They will use components of modern construction, but with tolerances no better than Clement could have provided... and, after a bit of tinkering and detail-debugging, they will find that the machine does indeed work.)

The Harvard Mark I (originally ASCC Mark I, Harvard-IBM Automatic Sequence Controlled Calculator) was built at Harvard University by Howard H. Aiken (1900-1973) and his team, partly financed by IBM - it became the first program controlled calculator. The whole machine is 51 feet long, weighs 5 tons, and incorporates 750,000 parts. It used 3304 electromechanical relays as on-off switches, had 72 accumulators (each with it's own arithmetic unit) as well as mechanical register with a capacity of 23 digits plus sign. The arithmetic is fixed-point, with a plugboard setting determining the number of decimal places. I/O facilities include card readers, a card punch, paper tape readers, and typewriters. There are 60 sets of rotary switches, each of which can be used as a constant register - sort of mechanical read-only memory. The program is read from one paper tape; data can be read from the other tapes, or the card readers, or from the constant registers. Conditional jumps are not available. However, in later years the machine is modified to support multiple paper tape readers for the program, with the transfer from one to another being conditional, sort of like a conditional subroutine call. Another addition allows the provision of plugboard-wired subroutines callable from the tape.

Used to create ballistics tables for the US Navy.

Max Newman, Wynn-Williams, and their team (including Alan Turing) at the secret Government Code and Cypher School ('Station X'), Bletchley Park, Bletchley, England, complete the "Heath Robinson". This is a specialized machine for cipher-breaking, not a general-purpose calculator or computer but some sort of logic device, using a combination of electronics and relay logic. It reads data optically at 2000 characters per second from 2 closed loops of paper tape, each typically about 1000 characters long. It was significant since it was the fore-runner of Colossus, see December 1943.

Newman knew Turing from Cambridge (Turing was a student of Newman's.), and had been the first person to see a draft of Turing's 1937 paper.

Heath Robinson is the name of a British cartoonist known for drawings of comical machines, like the American Rube Goldberg. Two later machines in the series will be named after London stores with "Robinson" in their names.

SSEM, Small Scale Experimental Machine or 'Baby' was built at Manchester University (UK), It ran it's first program on this date. Based on ideas from Jon von Neumann (a Hungarian Mathematician) about stored program computers, it was the first computer to store both it's programs and data in RAM, as modern computers so.

By 1949 the 'Baby' had grown, and aquired a magentic drum for more perminant storage, and it became the Manchester Mark I. The Ferranti MArk I was basically the same as the Manchester Mark I but faster and made for commmercial sale.

EDVAC (Electronic Discrete Variable Computer) completed at the Institute for Advanced Study, Princeton, USA (by Von Neumann and others).

Estimate that there are 100 computers in the world.

First Dot Matrix printer marketed by IBM.

Launch of IBM 360 - the first series of compatible computers.

DEC PDP-8 Mini Computer. The First Minicomputer, built by Digital EquipmentCost (DEC) it cost $16,000 to buy.

The first supercomputer, the Control Data CD6600, was developed.

Development of PASCAL finished - see 1967.

Cray 1, the first commercially developed Supercomputer, it contained 200,000 integrated circuits and was freon-cooled. It could perform 150 million floating point operations per second - it is now the basis of an informal measurement of the power Supercomputers, by the mid-1990s these had reached the 1000-'cray' mark! Supercomputers are also measured by the number of floating point operations they can do in a second, but this figure can be misleading as the definition of a floating point operation is open to some debate - but these operations are far more complicated than integer operations normally handled by Microcomputers. In 1992 the fastest Computer was the Cray-2, which can do around 250 million floating point operations per seconds. Cray have continued to develop even more powerful computers, such as the Cray Y-MP/832.

Such Supercomputers are used for weather forecasting, complex maths and physics problems, and animation in modern films.

Introduction of 8086 by Intel, the first commercially successful 16 bit processor. It was too expensive to implement in early computers, so an 8 bit version was developed (the 8088), which was chosen by IBM for the first IBM PC. This ensured the success of the x86 family of processors that succeeded the 8086 since they and their clones are used in every IBM PC compatible computer.

The available clock frequencies are 4.77, 8 and 10 MHz. It has an instruction set of about 300 operations. At introduction the fastest processor was the 8 MHz version which achieved 0.8 MIPs and contained 29,000 transistors.

Development of MS-DOS/PC-DOS began. Microsoft (known mainly for their programming languages) were commissioned to write the Operating System for the PC, Digital Research failed to get the contract (there is much legend as to the real reason for this). DR's Operating System, CP/M-86 was later shipped but it was actually easier to adapter older CP/M programs to DOS rather than CP/M-86, and CP/M-86 cost $495. As Microsoft didn't have an operating system to sell they bought Seattle Computer Product's 86-DOS which had been written by Tim Paterson earlier that year (86-DOS was also know as Q-DOS, Quick & Dirty Operating System, it was a more-or-less 16bit version of CP/M). The rights were actually bought in July 1981. It is reputed that IBM found over 300 bugs in the code when they subjected the operating system to their testing, and re-wrote much of the code.

Tim Paterson's DOS 1.0 was 4000 lines of assembler.

The Xerox 8010 ('Star') System, the first commerical system to use a WIMP (Windows, Icons, Menus and Pointing Devices) graphic user interface - from which all modern WIMP and Windowing systems have evolved. Apple used these concepts when designing the interface for the Apple Macintosh (see January 1984), and later alleged that Microsoft copied their 'look and feel' when designing Microsoft Windows.

The Xerox 'Star' was the commercialisation of the 'Alto', which had available internally inside Xerox PARC since 1973. Sales of the 'Star' were terrible and the system rapidly fell into obscurity.

Sinclair ZX81 was released, for a similar price to the ZX80 (see 1980).

MS-DOS 1.0., PC-DOS 1.0.

Microsoft (known mainly for their programming languages) were commissioned by IBM to write the operating system, they bought a program called 86-DOS from Tim Paterson which was loosely based on CP/M 80. The final program from Microsoft was marketed by IBM as PC-DOS and by Microsoft as MS-DOS, collaboration on subsequent versions continued until version 5.0 in 1991.

Compared to modern versions of DOS version 1 was very basic, the most notable difference was the presence of just 1 directory, the root directory, on each disk. Subdirectories were not supported until version 2.0 (March, 1983).

MS-DOS (and PC-DOS) was the main operating system for all IBM-PC compatible computers until 1995 when Windows '95 began to take over the market, and Microsoft turned its back on MS-DOS (leaving MS-DOS 6.22 from 1993 as the last version written - although the DOS Shell in Windows '95 calls itself MS-DOS version 7.0, and has some improved features like long filename support). According to Microsoft, in 1994, MS-DOS was running on some 100 million computers world-wide.

80286 Released. It supports clock frequencies of up to 20 MHz and implements a new mode of operation, protected mode - allowing access to more memory (up to 16 Mbytes compared to 1 MB for the 8086. The virtual address space can appear to be up to 1 GB through the use of virtual memory). It includes an extended instruction set to cope with this new mode of operation.

At introduction the fastest version ran at 12.5 MHz, achieved 2.7 MIPs and contained 134,000 transistors.

MS-DOS 2.01

DNS (Domain Name Server) introduced to the Internet, which then consisted of about 1000 hosts.

80386 DX released. It supports clock frequencies of up to 33 MHz and can address up to 4 GB of memory and virtual memory of up to 64 TERABYTES! It also includes a bigger instruction set than the 80286.

At the date of release the fastest version ran at 20 MHz and achieved 6.0 MIPs. It contained 275,000 transistors.

MS-DOS 3.2, PC-DOS 3.2

This version was the first to support 3½" disks, although only the 720KB ones. Version 3.2 remained the standard version until 1987 when version 3.3 was released with the IBM PS/2.

Macintosh II & Macintosh SE released. The SE was still based on the 68000, but could cope with 4 Mb of RAM and had a SCSI adapter, similar specifications to the Macintosh Plus of Jan. 1986.

The Macintosh II was based on the newer Motorola 68020, that ran at 16 MHz and achieved a much more respectable 2.6 MIPs (comparable to an 80286). It too had a SCSI adapter but was also fitted with a colour video adapter.

AD-LIB soundcard released. Not widely supported until a software company, Taito, released several games fully supporting AD-LIB - the word then spread how much the special sound effects and music enhanced the games.

Adlib, a Canadian Company, had a virtual monopoly until 1989 when the SoundBlaster card was released.

PC-DOS 4.0, MS-DOS 4.0

Version 3.4 - 4.x are confusing due to lack of correlation between IBM & Microsoft and also the USA & Europe. Several 'Internal Use only' versions were also produced.

This version reflected increases in hardware capabilities, it supported hard drives greater than 32 MB (up to 2 GB) and also EMS memory.

This version was not properly tested and was bug ridden, causing system crashes and loss of data. The original release was IBM's, but Microsoft's version 4.0 (in October) was no better and version 4.01 was released (in November) to correct this, then version 4.01a (in April 1989) as a further improvement. However many people could not trust this and reverted to version 3.3 while they waited for the complete re-write (version 5 - 3 years later). Beta's of Microsoft's version 4.0 were apparently shipped as early as '86 & '87.

80486 DX released by Intel. It contains the equivalent of about 1.2 million transistors. At the time of release the fastest version ran at 25 MHz and achieved up to 20 MIPs.

Later versions, such as the DX/2 and DX/4 versions achieved internal clock rates of up to 100 MHz.

Consortium of major SVGA card manufactures (called Video Electronic Standard Association, VESA) was formed and then introduced VESA SVGA Standard.

Introduction of ISA standard, although it was simply called the AT bus until after competing standards were launched that needed differentiating. Although the the AT bus had been used for many years it hadn't been properly standardised, causing all sorts of problems as newer PCs clocked the bus at ever faster speeds.

MS-DOS 5.0, PC-DOS 5.0

In order to promote OS/2 Bill Gates took every opportunity after it's release to say 'DOS is dead', however the development of DOS 5.0 lead to the permanent dropping of OS/2 development.

This version, after the mess of version 4, was properly tested through the distribution of Beta versions to over 7,500 users. This version included the ability to load device drivers and TSR programs above the 640KB boundary (into UMBs and the HMA), freeing more RAM for programs. This version marked the end of collaboration between Microsoft and IBM on DOS.

Linux is born with the following post to the Usenet Newsgroup comp.os.minix:

Hello everybody out there using minix-

I'm doing a (free) operating system (just a hobby, won't be

big and professional like gnu) for 386(486) AT clones.

The post was by a Finnish college student, Linus Torvalds, and this hobby grew from these humble beginnings into one of the most widely used UNIX-like operating systems in the world today. It now runs on many different types of computer, including the Sun SPARC and the Compaq Alpha, as well as many ARM, MIPS, PowerPC and Motorola 68000 based computers.

In 1992, the GNU project (http://www.gnu.org/) adopted the Linux kernel for use on GNU systems while they waited for the development of their own (Hurd) kernel to be completed. The GNU project's aim is to provide a complete and free UNIX like operating system, combining the Linux or Hurd platform with the a complete suite of free software to run on it. In order to allow it to carry the GNU name, the Linux kernel copyright was changed to the GNU Public License Agreement (http://www.gnu.org/copyleft/gpl.html) on the 1st of February 1992.

After 18 months of losses Apple were in serious financial trouble. Microsoft invested in Apple, buying 100,000 non-voting shares worth $150 million - a decision not approved of by many Apple owners! One of the conditions was that Apple were to drop their long running court case - attempting to sue Microsoft for copying the look and feel of their operating system when designing Windows.

There is some contention as to whether Apple were justified in sueing Microsoft, given that they themselves used some of the ideas from the XEROX 'Star' system when desiging their G.U.I. - however the similarities between MacOS and Windows are much more pronouced than those between the XEROX system and the Mac.