Photos: From the first PCs to the ThinkPad – classic IBM machines

Announced in 1980 the Selectric III typewriter expanded the keyboard to 92 characters.

Like its predecessor, the Correcting Selectric II, it has a correcting key that can erase the previously typed character.

This IBM 1052 was a console output printer for System/360 machines in the 1960s.

It was a cut-down Selectric I/O printer with no backspace and no tab. Keyboard input was provided by a separate keyboard.

The IBM Electronic Composer, announced in 1975, had the ability to store about 5,000 characters in its memory.

Users were able to work on two different documents, thanks to the machine having a main and alternate storage area.

The machine had two power switches, one for the typewriter portion and the second for the memory — which, if powered down, would result in the documents being lost.

The machine was an improvement over IBM's earlier Selectric Composer as the user could have the machine retype stored documents differently justified, rather than having to manually retype them.

One of IBM's early experiments with releasing smaller computer systems was the IBM 5110 Computing System from 1978.

The 5110 was designed to be used for automating common business tasks, such as general ledger and accounts payable. It could also be reprogrammed to provide reports to help management analyse sales, schedule resources, reduce inventory cost and plan future growth.

The 5110 featured a desktop unit that housed a CPU, a keyboard and a 1,024-character display screen. The desktop system unit alone weighed 50 pounds.

It was available with between 16KB and 64KB of memory, and could store as much as 204,000 bytes of information per tape cartridge or 1.2 million bytes on a single diskette.

The Displaywriter System, announced in June 1980, introduced some of the convenience of PC word processing software at a time when documents were generally created on typewriters.

The machine could store and recall documents so they could be revised and could check the spelling of 50,000 commonly-used words.

The system was designed to allow users to produce high quality documents at "rough draft speed".

Displaywriter featured an Intel 8086 processor with 160KB, 192KB or 224KB of RAM and was available with a single or double diskette unit.

A basic system included a display with a typewriter-like keyboard, a printer and a device to read and write to diskettes, which was capable of storing more than 100 pages of text.

Two printers were available with the machine, initially the 5215, a Selectric-based printer similar to the magnetic card Selectric typewriters and later an IBM 'Daisywheel' printer.

The System/23 Datamaster was announced by IBM's General Systems Division in July 1981, only one month before the IBM PC.

The Datamaster is an all-in-one computer with a built-in text mode CRT display, keyboard and two 8-inch floppy disk drives.

The machine was powered by an 8-bit 8085 and had 256KB of memory. A BASIC interpreter was also built into the computer.

The intention of Datamaster was to provide a computer that could be operated without specialists and the machine was designed to be operated by novice users.

The machine came with a choice of two printers and accounting and word processing software. A full function data processing installation, with a single computer and an 80 character-per-second printer cost $9,830, which according to IBM was its "cheapest solution at that time".

In 1981 IBM decided to move beyond the mainframes it had been building for decades and launch its first mass market personal computer, the IBM 5150.

The PC was a success for IBM — particularly in the office market — shipping more than 800,000 units in the two years after it went on sale. What helped drive the machine’s popularity was both the familiarity of the IBM name and the broad range of peripherals and software available for the computer.

The machine spawned a market in IBM-PC clones, known as IBM PC compatibles, made possible by the fact that the machines were built using off the shelf non-IBM hardware and that Microsoft was free to licence DOS for use on third-party machines. The spread of IBM PC compatible machines created a common standard for PCs, simplifying the process of buying a PC by ensuring that any IBM compatible PC would run the same software, no matter which company made it.

The machine's starting price was $1,565, it ran on a 4.77Mhz Intel 8088 microprocessor, came with a keyboard, ran Microsoft DOS, supported up to 256KB of RAM and a colour display, came with an optional 160K floppy disc drive and an optional colour monitor.

This machine is attached to an IBM PC monochrome display and an IBM dot-matrix printer.

The IBM PC monitor, announced in 1981, could output both text and graphics.

It could manage two graphics modes, a resolution of 320 x 200 pixels with up to four colours or 640 x 200 pixels with a monochrome display.

The monitor had four text modes, based on either 40 columns by 25 lines or 80 columns by 25 lines, with up to 16 colours.

It was usually driven by an IBM PC Color/Graphics Adapter (CGA), which included a Motorola MC6845 display controller and 16KB of video memory. It had a 4-bit RGB1 interface.

The IBM 5155 Portable PC might weigh as much as a small suitcase but it was portable, something that couldn't be said of most computers when it was released in 1984.

The machine was deemed "luggable", a reference to its heft and the fact it weighed a not inconsiderable 30 pounds — roughly 30 times more than an iPad Air.

Inside the computer was an IBM PC XT motherboard with an Intel 8088 processor running at 4.77MHz (the same as the original IBM PC).

It came with 256KB of RAM, expandable to 640KB. It had one or two 360KB half-height 5.25-inch diskette (floppy disk) drives and an IBM PC colour graphics adapter driving a built-in nine-inch orange monochrome CRT display.

The Portable PC's operating system was IBM PC Dos 2.1 or later.

The IBM 5216 Wheelprinter, released in the early 1980s, was designed to be attached to a PC.

The machine uses daisy-wheel printing technology, where raised characters are set on spokes radiating out from a central hub. The machine's print mechanism is a simplified version of that of the IBM 5218 Displaywriter printer.

The IBM Proprinter II was one of IBM's second generation printers for personal computers.

The machine is a 9-wire dot-matrix printer that can produce 40 characters per second at high quality settings and 200 characters per second at lower quality.

It connects to a PC via Centronics parallel interface.

The IBM PC AT was the company's second-generation personal computer and was announced in 1984.

The machine was initially powered by an Intel 286 processor running at 6MHz, while later models ran at 8MHz.

The PC AT could support up to 16MB of RAM and initially had one 20MB hard drive. Expansion was via six 16-bit expansion slots and two 8-bit slots.

The display was usually driven by an IBM monochrome Display/Printer adapter or an IBM Colour/Graphics Adapter. Machines released later used the IBM Enhanced Graphics Adapter and, sometimes, Professional Graphics Adapters.

IBM produced a number of point of sale terminals, such as this 1985 IBM 4683 machine.

The 4860 system consists of a PC-based controller and thin client-based POS terminal, typically connected via a Token ring network.

The lightweight, for the time, IBM PC Convertible can be considered to be IBM's first laptop.

Released in 1986 the machine used a 4.77MHz Intel 8088 processor and came with up to 256KB of RAM, expandable to 640KB.

It came with a monochrome CGA-compatible LCD screen and twin 720KB 3.5-inch floppy disk drives.

In total the machine weighed less than 13 pounds or 6kg, thanks in part to its use of the latest surface mount technology to allow more components to be packed into a smaller area.

The IBM RT PC, known as the IBM 6150 in the UK, is based around IBM's ROMP processor. It was introduced in 1986 as the Risc Technology Personal Computer.

The machine ran IBM AIX, Advanced Interactive Executive, an IBM port of UNIX 1.x and 2.x but could also run the Academic Operating System (AOS) or Pick Operating System.

It was followed in 1990 by the IBM RS/600 and the POWER (Performance Optimisation with Advanced Risc) processor line, which was the basis for the PowerPC processor.

This IBM 3151 ASCII series machine is an asynchronous serial communication terminal released in 1987.

It uses the ASCII (American Standard Code for Information Interchange) code set as opposed to the Extended Binary Coded Decimal Interchange Code set more commonly found on IBM terminals.

The system has a 14-inch CRT display that can display 80-132 characters by 24 lines. It can be attached to both IBM and non-IBM computers.

The IBM PS/2 Model 80 was announced in April 1987. The IBM PS/2 was the third generation of IBM PCs.

Unlike previous IBM PCs the model 80 used a new bus called Micro Channel Architecture. The model 80 has an Intel 386 processor, with 1MB or 2MB of RAM and a VGA display adapter.

The machine could run IBM PC DOS 3.3, OS/2, Microsoft PC Xenix and IBM AIX PC.

This computer has two 3.5-inch 2,88MB diskette drive and a 115MB Enhanced Small Disk Interface hard disk.

This portable machine was again classed as a "luggable" as it is portable but weighs more than 20 pounds.

The IBM PS/2 P70-386, released in 1989, has an Intel 386DX processor and supports up to 8MB of RAM.

The PC had a built-in plasma display and its VGA adapter could also power several different external PS/2 monitors.

The machine could run IBM PC DOS 3.3, OS/2, Microsoft Xenix or AIX PC.

Announced in October 1990, the IBM PS/2 Model 95 could be powered by a number of processors, from a 20MHz Intel 486 to a 90MHz Intel Pentium.

The model 95 has a fully interchangeable processor complex motherboard: containing the processor, memory controller and micro channel interface. It has a 32-bit Micro Channel Architecture bus.

The machine supports from 8MB to 64MB of DRAM, in eight 72-pin sockets.

The SCSI adapter can support both internal and external devices, such as hard disks, tape drives and CD drives.

The IBM Personal System/2 L40 SX laptop PC was announced in 1991.

A replacement for IBM's earlier IBM PC Convertible laptop, it was powered by an Intel 386SX 20MHz processor. In spite of being a PS/2 (which were mostly micro channel architecture) it had a PC AT bus.

It could support between 2MB and 18MB of RAM, had one 3.5-inch floppy drive and a 60MB hard disk. An illuminated VGA monochrome LCD screen served as its display.

The PS/2 LX 40 SX was later superseded by the successful IBM ThinkPad range of machines.

In 1992, IBM announced a new series of notebook computers — the ThinkPad.

Featuring a distinctive black case and a TrackPoint pointing device in the middle of the keyboard, the ThinkPad won more than 300 awards for design and quality.

The name comes from the small flip open notebook carried by IBM customer engineers to jot down reminders. The pads had "IBM" embossed in gold letters on one side and "THINK" on the other, and were known as "Think Pads" by the engineers.

This is an early example of a ThinkPad, a model 720. The machine is powered by a 50MHz 486 SLC CPU, can support up to 16MB RAM and a 120MB hard disk.

The display is a 9.54-inch LCD screen with a 640x480 resolution.

The first of the IBM Aptiva PC family was announced in September 1994 as a replacement for the PS/1 line. It was sold until May 2001, when IBM pulled out of the home computing market.

Initially PCs in the Aptiva brand were powered by Intel 486 processors, while later models had more powerful Intel Pentium and AMD CPUs.

Like the PS/1 family Aptiva PCs were sold as bundles that included the monitor, keyboard, mouse and speakers, as well as an installed operating system. During the lifetime of the family that OS changed from PC DOS/Windows 3.1 to the OS/2 Warp.

The Aptiva shown here is a Machine Type 2138 Model E82.

The design of the ThinkPad 701 allowed it to pack an 11.5-inch keyboard into a 9.7-inch notebook.

When the lid of the machine, released in 1995, is opened up the full-size keyboard unfolds and slides into place.

As later ThinkPads featured larger screens the need for a fold-out keyboard was eliminated and the 701 was the only ThinkPad to use this "Butterfly" keyboard.

The 701 is powered by a 486DX4/75 processor and weighs only 4.5 pounds.

The "Butterfly" keyboard won plaudits for its design and was put on display at the Museum of Modern Art in New York.

This IBM Intellistation computer, a workstation-class PC first released in 1997, is running IBM Network Station Manager under Windows 2000 Server.

Network Station Manager is the software needed to boot and manage a group of IBM Network Stations.

The Network Station is connected to this server via TCP/IP over a Token ring LAN, a networking protocol now not commonly used.

Unlike Ethernet technology, Token ring passed a "token" between stations. Only a station in possession of a token could transmit on the LAN, thus avoiding collisions and therefore giving a more deterministic performance.

The advent of Ethernet switching largely removed the disadvantages of Ethernet's protocol and thus today it's the primary LAN of choice.

Announced in 1998, the RS/6000 43P Model 150 was an entry-level desktop workstation powered by an IBM 375MHz PowerPC 604e processor.

The machine could support up to 1GB of RAM and ran the AIX OS. It had five PCI adapter slots and three media bays.

The PC was withdrawn from sale in 2003.

This IBM ThinkPad 770X was a high-end machine at the time of its release in the late 1990s.

It featured a 300MHz Intel Pentium II processor, 128MB of memory, a 14.1-inch TFT screen.

The PC weighed seven pounds and had a battery life of four hours.