The IBM 6580 Displaywriter System is a 16-bit microcomputer that was marketed and sold by IBM's Office Products Division primarily as a word processor. Announced on June 17, 1980 and effectively withdrawn from marketing on July 2, 1986, the system was sold with a 5 MHz Intel 8086, 128 KB to 448 KB of RAM, a swivel-mounted monochrome CRT monitor, a detached keyboard, a detached 8" floppy disk drive enclosure with one or two drives, and a detached daisy wheel printer, or Selectric typewriter printer. The primary operating system for the Displaywriter is IBM's internally developed word processing software titled "Textpack", but UCSD p-System, CP/M-86, and MS-DOS were also offered by IBM, Digital Research, and CompuSystems, respectively.

Textpack is a proprietary word processing suite developed specifically for the Displaywriter, that was aimed at automating document creation and finalization. Though capable of multi-tasking, Textpack is not a general purpose operating system like DOS or CP/M. Instead, it bootstraps directly to a menu of text editing and pagination functions, with additional options to manage Textpack data disks or load one of several IBM supplemental programs, called "Feature Programs". Textpack was offered in six versions, titled: "E", "1", "2", "3", "4", & "6". These versions of Textpack were tiered in functionality, with only basic text editing being offered with the lowest Textpack versions, E and 1. More advanced features, such as customizing keyboard macros and menu shortcuts, automatically generating custom headers and footers, automatically processing math equations, or emulating a 3101 or 3270 terminal, were reserved for Textpack 4 or Textpack 6. If the Displaywriter system possesses enough RAM, and is running Textpack 4 or 6, it can also load a Feature Program concurrently with a document, and tab between editing the document and the Feature Program in real time.

According to IBM, the approach of offering stripped down versions of the full Textpack product was an attempt to make the Displaywriter more economical for smaller businesses, who IBM envisioned would choose a cheaper software package and then upgrade as their needs required. However, in practice this was undercut by both the Displaywriter hardware being significantly more expensive than competition in the word processing and general microcomputer spaces and the fact that limitations coded into Textpack prevented a fluid upgrade path for customers in many instances. For example, if a customer were using Textpack 1 and wanted to use their Displaywriter to create graphs and charts, they would need to pay approximately $1,500 ($4,500 in 2023) for Textpack 4, the Chartpack software disk, and the RAM upgrade to support the new software.

During the production lifespan of the Displaywriter, Textpack was praised for its functionality and ease of use compared to other word processing options, though the high price tag was criticized, especially in comparison to the IBM 5150 PC and other compatibles. As a result of this, Displaywriter Textpack found strong adoption with clients that had deep pockets, such as in government, higher education, and legal sectors, and poor adoption with smaller businesses and at-home users. Despite selling UCSD p-System for Displaywriter directly and initially working with Digital Research to create a CP/M-86 port for Displaywriter, the Displaywriter was not ever strongly marketed as a true microcomputer, and was almost always sold with Textpack. Additionally, the Displaywriter never received any significant display updates to bring its graphical capabilities up to par with the IBM PC or compatibles. As a result, by 1983, the Displaywriter had lost any true market niche, and in 1984, IBM announced "DisplayWrite", an almost exact replica of the Displaywriter Textpack for the IBM Personal Computer line, making the Displaywriter truly obsolete. The established large contracts with government entities, including the Reagan administration and military buoyed the sales slightly until the Displaywriter was soft

Textpacks 4 and 6 also offered the ability to combine all program disks into a single DS DD floppy, which could then also be used for document storage if space remained on the disk.

According to IBM, this tiered approach of incorporating multiple levels of operating systems and associated feature programs, was an attempt to make the Displaywriter more economical for smaller businesses, who could choose a cheaper software package and then upgrade as their needs required. The Textpack version could be increased without having to repurchase feature programs, and new feature programs could usually be integrated without having to increase the Textpack version. That said, revisions of feature programs are keyed to Textpack maintenance levels. For example, a revision of Textpack 4 from 1984 could not use a revision of a feature program from 1982, it would require a newer revision of that feature program from 1984. IBM used the six character disk labels of the program disks to determine whether one disk was compatible with another. If a disk label of a noncompatible program diskette is changed to a label associated with a compatible diskette, the Displaywriter will attempt to execute the disk as if it contained the correct software, but certain features will either not function properly, or Textpack will abend.

Diskettes used within Textpack are always formatted as either 284 kB capacity if the disk is 1D, or 985 kB capacity if the disk is 2D, regardless of a disk's actual advertized capacity. This is a software limitation of Textpack, and not a hardware limitation of the Displaywriter. Because there is no user accessible setting to designate disk sector size within Textpack, the operating system arbitrarily assumes that all 1D disks are rated as SS SD with 256B sectors and that all 2D disks are rated as DS DD with 256B sectors, which results in the aforementioned capacities. The format that Textpack diskettes utilized, though similar to the IBM 3740 Data Entry System, was uniquely proprietary and not interchangeable with any other IBM system, including the Displaywriter's predecessor, the Office System 6. Text created in Textpack is stored in a file structure unique to the Displaywriter and is encoded with 8-bit EBCDIC. The Displaywriter also supports ASCII, but 8-bit EBCDIC is used in this context in order to take advantage of the 256 characters available per EBCDIC font set, compared to the maximum of 128 characters available per ASCII font set. The Displaywriter uses two of these EBCDIC 256 character font sets, which are stored in ROM on the display adapter card in either two or four PROM chips depending on the card revision, in order to achieve a total of 512 possible available characters. When instructed, the Displaywriter draws from these font sets to generate a working character table in RAM for the operating system to use. Only 256 of the available 512 characters can be used concurrently by the user, but characters from either character set can be mixed and matched to total up to 256 and characters can be hot swapped to in software. Changing characters can be done in Textpack by using the "keyboard change" button on the keyboard. The ASCII code set is accessible within Textpack while using the Asynchronous or Bisynchronous communication features, where the Displaywriter converts the stored EBCDIC characters into ASCII before transmitting and after receiving text. Additionally, if the user wishes to type in ASCII directly during a communication session, they can change the keyboard to keyboard #103 which is the standard ASCII keyboard. While in ASCII mode the Displaywriter can generate all printable ASCII characters. ASCII control characters can be accessed at any time, even in EBCDIC mode, by depressing the control key (the blank key above REQST on the keyboard), and then pressing a corresponding key in the alphanumeric block. This is because they don't add to the 256 displayable character total.

UCSD p-System was the official "data processing" operating system for the Displaywriter, offered by IBM through contract with Softech Microsystems. Announced in September 1982 and made available in December 1982, as part of the contract, p-System was extensively supported by Softech Microsystems, and had multiple feature upgrades offered from IBM as time went on.