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The Waldorf, 12 August 1981

On 12 August 1981, Don Estridge unveiled IBM's new Personal Computer, model 5150, at New York's Waldorf Hotel, bringing IBM into the mass-market personal-computer business.

The announced entry configuration cost US$1,565 with 16 KB of RAM and no disk drive. A display, two diskette drives and a printer added nearly $3,000.

What was inside, and what was published

The machine ran a 4.77 MHz Intel 8088. Microsoft supplied the operating system IBM marketed as PC DOS.

IBM also published unusually extensive technical information, meant to help outside companies build software and peripherals. That did not put everything in the public domain — compatible makers still had to avoid copying protected BIOS code.

A year from pitch to podium

William C. Lowe had pitched IBM leadership on a roughly $1,500 consumer and small-business computer before development passed to Estridge. Project Chess ran a one-year crash program built around available third-party components.

Apple, Radio Shack and Commodore were already selling personal computers. What was new was IBM's entry, with an official product, price and a dealer strategy spanning IBM outlets, Sears and ComputerLand.

Volume 315, pages 207–210

The 16 May 1985 issue of Nature carried Joe Farman, Brian Gardiner and Jonathan Shanklin's paper, “Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction.”

Using long-running measurements from the British Antarctic Survey stations at Halley and Faraday, the authors reported that Antarctic spring ozone had fallen dramatically and argued that ordinary one-dimensional global models were inadequate.

A decade of backlog

Springtime values had begun declining around the late 1970s. By October 1984 the ozone layer over Halley was only about two-thirds as thick as in earlier decades, against expectations of changes of a few percent.

Shanklin helped expose the pattern by working through a backlog of handwritten Dobson-spectrophotometer observations, which showed the low readings were systematic rather than instrument error. The record itself ran back to the 1956 International Geophysical Year — it was not a purpose-built search for a hole.

What the paper did and did not say

It proposed a chemical connection to increasing inorganic chlorine under Antarctica's uniquely cold stratospheric conditions, but did not present the complete polar-cloud chemistry that later fieldwork established.

It also did not announce a literal opening in the atmosphere; the term “ozone hole” and the satellite maps became common afterwards. NASA researchers soon revisited satellite readings that automatic quality-control software had flagged as implausibly low, and found corroborating Antarctic data.

Even the date is looser than it looks: 16 May is the printed issue date for volume 315, while Nature's current metadata gives “Published: 01 May 1985.”

01:23:40, 26 April 1986

On 26 April 1986, during a planned shutdown of Unit 4, operators were testing whether a coasting turbine-generator could power coolant pumps and emergency equipment until diesel generators started after a loss of external power.

The senior reactor-control engineer pressed the emergency shutdown button. In the reactor's abnormal state, defective control-rod design initially added reactivity — the rods displaced neutron-absorbing water before their absorber sections entered the core. By about 01:24, severe shocks and explosions were destroying Unit 4.

Design, not just operators

The crew had brought the RBMK into a poorly understood low-power configuration with too little operating reactivity margin. In that unstable state, the large positive void coefficient and the defective control-rod design helped turn the shutdown into an uncontrollable power excursion.

IAEA's revised account treats the accident as a combination of design defects, deficient procedures, weak safety culture and operator actions — and says the exact initiating sequence may never be known with certainty. INSAG-7 also found that isolating the emergency core cooling system did not initiate or affect the accident's development.

The next 36 hours

Roughly 600 workers were at the site that morning. Plant personnel and firefighters suppressed numerous fires within hours, keeping them from spreading to the other operating units, while the destroyed reactor kept releasing radionuclides.

Pripyat was not evacuated that day. Its 49,360 residents were moved starting at 2 p.m. on 27 April, and the Soviet Union publicly acknowledged an accident on 28 April, after elevated radiation was detected abroad.

29 May 1988: the fourth summit

On 29 May 1988, President Ronald Reagan arrived in Moscow and joined Soviet general secretary Mikhail Gorbachev for the opening ceremony. The Moscow meetings ran through 2 June.

It was their fourth summit in three years, after Geneva in 1985, Reykjavík in 1986 and Washington in 1987. Talks covered arms control, human rights and humanitarian issues, regional conflicts and bilateral relations.

1 June: the exchange in St. Vladimir's Hall

Reagan and Gorbachev exchanged the instruments of ratification for the INF Treaty in the Grand Kremlin Palace. The treaty had been signed in Washington in December 1987; this exchange brought it into force.

The U.S. Senate had approved ratification immediately before Reagan's trip. Reagan noted at the ceremony that inspection teams were already residing in each other's countries.

What else came out of it

The summit produced an agreement requiring advance notification of ICBM and submarine-launched ballistic-missile launches, plus several bilateral cooperation agreements.

On START, the sides recorded common ground — including ceilings of 1,600 strategic delivery systems and 6,000 warheads — while acknowledging important work remained. Shultz and Shevardnadze were instructed to continue in Geneva.

Two months, then signatures

On 5 April 1989, representatives of Poland's communist authorities and the Solidarity-aligned opposition signed the Round Table accords in Warsaw, closing negotiations that had begun on 6 February. Church representatives had taken part as observers.

Czesław Kiszczak, the interior minister, led the government side; Lech Wałęsa led the opposition. What they signed was not one short treaty but a package of principal documents on political reform, social and economic policy, and trade-union pluralism.

The seat arithmetic

The political settlement provided for a restored, freely elected Senate of 100 seats and opened 161 Sejm seats — 35 percent — to free competition.

The other 299 seats, 65 percent, were reserved for the governing coalition and allied organizations. The presidency was also to be restored. Wałęsa publicly called the bargain the minimum needed to begin democratic transformation.

Promises, not yet law

The accords committed the authorities to relegalizing Solidarity but did not themselves complete its court registration, which came on 17 April.

They called for parliamentary elections without fixing a date: the Council of State set 4 and 18 June only on 13 April. The Sejm enacted the constitutional amendments and electoral laws on 7 April.

The opening of Parliament, Cape Town

On 2 February 1990, State President F. W. de Klerk announced that the prohibitions on the African National Congress, Pan Africanist Congress, South African Communist Party and their subsidiary organizations were being rescinded.

He announced the release of people imprisoned merely for membership in those organizations or for offenses created solely by their prohibition — expressly excluding prisoners convicted of offenses such as murder, terrorism or arson.

33 organizations, 374 people

De Klerk removed emergency restrictions from 33 organizations and release conditions from 374 people, abolished the media and education emergency regulations, and gave emergency detainees rights to legal representation and a doctor of their choosing. The maximum emergency-detention period was set at six months.

The state of emergency itself stayed in force, and de Klerk paired the reforms with a promise of stronger law enforcement. Implementation was declared immediate, with notices to appear in the Government Gazette the next day.

Nine days short of the gate

The government had firmly decided to release Nelson Mandela unconditionally, de Klerk said, but the date was not yet determined: logistical and safety arrangements would take a little longer.

Mandela, imprisoned since 1962 and serving a life sentence from the Rivonia Trial, remained at Victor Verster Prison until 11 February — 27 years in custody.

Palais Schaumburg, 18 May 1990

On 18 May 1990, West German Finance Minister Theo Waigel and East German Finance Minister Walter Romberg signed the State Treaty establishing a Monetary, Economic and Social Union in Bonn, with Chancellor Helmut Kohl witnessing.

Negotiations had begun on 27 April and produced the treaty in barely three weeks, under pressure from the GDR's worsening economic condition and continuing migration.

One currency, from 1 July

The treaty fixed 1 July 1990 as the start of a single currency area using the Deutsche Mark, with the Deutsche Bundesbank as central bank. The ordinary conversion rate was DM 1 for 2 GDR marks, with specified exceptions, and adults could exchange up to 4,000 GDR marks at 1:1.

Federal budget-balancing allocations to the GDR were set at DM 22 billion for the second half of 1990 and DM 35 billion for 1991, alongside a DM 115 billion Unity Fund agreed shortly before signing.

Not the Unification Treaty

The GDR was required to replace its socialist planned-economy foundations with a social market economy based on private ownership, competition, free prices and free movement of labour, capital, goods and services. Its unemployment, pension, health, accident-insurance and social-assistance systems were to be aligned with West German principles.

This was an initial step toward state unity, not unity itself. Accession was fixed by the Volkskammer on 23 August, detailed in the Unification Treaty of 31 August, and completed on 3 October 1990.

A vote just before 3 a.m.

The freely elected East German Volkskammer met in overnight special session at the Palace of the Republic in East Berlin and voted for the GDR to accede to the territory governed by West Germany's Basic Law. The sitting had begun on the evening of 22 August; the vote came shortly before 3 a.m. on 23 August 1990.

The resolution invoked Article 23 of the Basic Law and fixed the accession's effective date as 3 October 1990. Of the 363 votes cast, 294 were in favour, 62 against and seven abstentions.

The date was settled in the room

Deputies arrived without an agreed date. Rival factions had proposed immediate accession, 15 September or 14 October, while the GDR government was breaking apart and the state's economic deterioration accelerated.

The text that passed was a joint amendment agreed during the session by the CDU/DA, DSU, FDP and SPD parliamentary groups. Günther Krause, the CDU parliamentary leader and GDR negotiator, signalled during the debate that 3 October was the earliest workable date.

Gregor Gysi, the PDS parliamentary leader, opposed the method and characterised the result as a decision for the GDR's demise.

What the resolution assumed

The resolution assumed that the Unification Treaty negotiations, the Two Plus Four security settlement and preparations for elections in the re-established Länder would be sufficiently complete by the chosen date. The treaty had not yet been signed, and accession itself would not occur until 3 October.

Later that day Chancellor Helmut Kohl welcomed the resolution before the West German Bundestag, repeating its conditions and its date. Negotiators finished and signed the detailed Unification Treaty on 31 August, eight days later.

22 August 1991: an emergency session

At an emergency session in Moscow on 22 August 1991, the Supreme Soviet of the Russian SFSR adopted a resolution recognising the historical white-azure-scarlet tricolor as the official National Flag of the Russian Federation. The hard-line coup against Soviet president Mikhail Gorbachev had collapsed the day before.

The tricolor was raised over the Russian parliament building — the Moscow White House — in place of the Russian SFSR's Soviet-era red flag. Reports give the time as noon.

Recognised only until a symbols law

The resolution was expressly interim: it recognised the tricolor pending a special law establishing new state symbols. Ruslan Khasbulatov, first deputy chairman of the Supreme Soviet, autographed the archived text.

Contemporary reporting described Boris Yeltsin announcing the tricolor as Russia's official flag during the post-coup victory gathering outside parliament. One correspondent put the crowd at 100,000.

What the flag change did not do

The resolution concerned the Russian SFSR and Russian Federation, not the still-existing Soviet Union. The Soviet flag stayed over the Kremlin until 25 December 1991.

The tricolor's status was written into the RSFSR Constitution on 1 November 1991. Because the exact specification was standardised later still, the August 1991 cloth should not be assumed to match today's flag in every legal detail.

31 March 1991: restoration, not creation

Georgia held a binding referendum on 31 March 1991 asking whether its state independence should be restored on the basis of the Act of Independence of 26 May 1918. A month earlier, on 28 February, the Supreme Council had decreed that the USSR-wide referendum on preserving a renewed union would not be held under Georgian authority.

From a registered electorate of 3,672,403, some 3,326,100 ballots were cast — a turnout of 90.57%. The recorded result was 3,295,493 affirmative votes and 16,917 negative; under Georgia's referendum law the proposal was deemed adopted.

Where the vote did not reach

Voting was not conducted in the Tskhinvali, Kornisi or Java districts, though some displaced or travelling voters from affected districts cast ballots elsewhere. Participation in Abkhazia was substantially lower than the national rate.

The commission recorded 474 voters from Java district casting ballots in Sachkhere, every one of them affirmative. Its detailed report also notes polling in two Ossetian-populated villages but excludes those totals, because the local commission had not been constituted according to law.

From mandate to act, nine days later

The Central Election Commission certified the proposal as adopted on 4 April and published detailed territorial results on 5 April. Former U.S. president Richard Nixon, privately visiting Georgia, had toured polling stations on referendum day.

On 9 April the Supreme Council relied on that mandate to adopt the Act of Restoration of State Independence of Georgia — the second anniversary of the Soviet army's deadly crackdown on demonstrators in Tbilisi.

10 May 1994 at the Union Buildings

Nelson Mandela took the presidential oath before Chief Justice Michael Corbett and signed it at the Union Buildings in Pretoria on 10 May 1994. The newly constituted National Assembly had elected him unanimously the day before.

In his inaugural address he described himself as the first president of a united, democratic, non-racial and non-sexist government, and committed the new government to reconciliation, nation-building and peace.

Two deputy presidents, one of them the man he replaced

Thabo Mbeki and the outgoing president, F. W. de Klerk, were sworn in as deputy presidents in the Government of National Unity. De Klerk handed over the presidency and then took office under Mandela.

The ANC had won 12,237,655 national votes — 62.65% of valid votes — and 252 of the National Assembly's 400 seats. The coalition cabinet was announced on 11 May.

The flypast, and a football match

South African military aircraft flew over the ceremony trailing the colours of the new national flag. Witnesses initially tensed at the sound before recognising the flypast as a salute to the new commander-in-chief.

After the Union Buildings ceremony and the luncheon, Mandela flew by helicopter to Ellis Park for a South Africa–Zambia football match.

Midnight, 30 April 1995

At midnight on 30 April 1995, the National Science Foundation decommissioned the NSFNET Backbone Service after a two-year transition of its commodity backbone functions to commercial providers. The shutdown applied to that dedicated NSF-funded backbone, not to the Internet as a whole.

NSFNET connected about 2,000 computers in 1986 and more than two million by 1993, and its backbone eventually reached 45 megabits per second. Merit Network had managed it since 1987 in partnership with IBM and MCI.

No single successor

U.S. Internet traffic moved among several privately operated backbones rather than through one replacement owner or system. By summer 1995 there were at least 14 commercial or other high-speed national and super-regional TCP/IP networks.

NSF's announcement said most consumers would experience no change in service or fees as a direct result of the backbone shutdown.

What NSF kept paying for

NSF continued subsidising regional research and education networks on a declining scale — 100% in the first year, then 75%, 50% and 25%. It estimated the average research or educational institution would face roughly $1,500 in additional annual connectivity cost.

The foundation also funded the vBNS research backbone, institutional and international connections, InterNIC and networking research. The government did not stop funding the Internet on 30 April.