IBM Displaywriter System

The primary Displaywriter operating system, Textpack, is a word processing suite that was aimed at automating document creation and finalization. It was offered in six variants (1, E, 2, 3, 4, & 6) each sporting progressively more features. These features varied from basic text editing with the lowest Textpacks, E and 1, to being able to spell check, mail merge, automatically generate headers and footers, customize menu shortcuts, save and recall macros, process light arithmetic and simultaneously run additional IBM programs, such as a 3278 terminal session with Textpack 6. 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.

Though technically capable of multi-tasking, Textpack is not a general purpose operating system. It bootstraps to a menu of text editing and pagination functions, with the option to also load one of several IBM supplemental programs, called "Feature Programs". These programs included: "Chartpack", a program to create business charts that could be inserted into typed documents; "Reportpack", a program to create and manage lists of data; "Language pack", to provide spell checking in 11 languages; "Extended Spelling Dictionary", which provided spell checking for United States legal terminology; "Electronic Document Distribution", to share Displaywriter documents with a S/370 mainframe; Bisynchronous and Asynchronous communications; 3277 terminal emulation; 3278 terminal emulation; IBM mag card conversion software; a "PC attach program",[6] which allowed file sharing and fixed disk sharing with an IBM PC/jr/XT; and also several tailored templates for specialized data processing including "Administrative Support", "Educational Fund Raising", "Title Insurance",[7] "Applicant Processing" and "Personnel Report".

According to IBM, this tiered approach with 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 number could be increased without having to repurchase feature programs, and new feature programs could usually be used without having to upgrade the Textpack number. That said, revisions of feature programs are keyed to the maintenance level of the Textpacks they were meant for. For example, a revision of Textpack 4 from 1984 could not use a revision of a feature diskette from 1982, it would require a revision of that feature program from 1984. IBM used the disk labels of the program disks to determine whether one disk was compatible with another. If a noncompatible disk label is changed to a label associated with a compatible diskette, the Displaywriter will attempt to execute the software but certain features will not function properly, or Textpack will outright crash.

Within Textpack, disks are always formatted as either 1D 284KB capacity, or 2D 985KB capacity disks, regardless of a disk's actual rating. This is a software limitation of Textpack. Because there is no setting to designate disk sector size, Textpack will always choose a sector size of 256B, which results in the aforementioned capacities. The format that the storage diskettes used, though similar to the 3740, was uniquely proprietary. Text created in Textpack is stored in a file structure unique to the Displaywriter and is encoded with 8-bit EBCDIC. 8-bit EBCDIC is used in this context in order to take advantage of the full 256 characters available per EBCDIC font set vs the maximum of 128 available per ASCII font set. The Displaywriter uses two of these EBCDIC 256 character font sets to make up a total of 512 available characters. All characters can be switched to in software, but only 256 characters can be accessed by the keyboard at any given time. Accessing a character outside of the 256 currently available necessitates a character change, which can be done using the keyboard change button on the keyboard. The Displaywriter also natively supports the 7-bit ASCII code set.[8] 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 for transmission. 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.[9] 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.

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. When purchasing UCSD p-System for Displaywriter, the purchaser could chose between p-System Runtime, or p-System "Development System", which was the same as Runtime, but was bundled with a BASIC compiler or an additional Fortran-77, 8086 Assembly code, or PASCAL compiler. IBM also sold a software upgrade that would provide p-System with the appropriate I/O calls for the RS232 port(s) on the Displaywriter's communications card, as well as a conversion utility, titled "B&H Exchange Utility", to convert UCSD format files to "B&H" format files, which is the file structure used on the System/23 Datamaster, System/36 and System/38. p-System did not pick up much steam on the Displaywriter, but was notably used by the USDA Rural Development as the operating system for the "Farmer Program Servicing Action System",[10] which was a custom software suite written by the Rural Development agency. Additional programs offered by IBM for Displaywriter p-System included: "Financial Planning and Report Generating System",[11] which was an advanced version of Reportpack that included financial modeling and easier report generation, "QUICKSTART Utility", which decreased load time of large programs,[12] and "Money-Track"[13] financial tracking by Pacific Data Systems.

Digital Research announced CP/M-86 v1.1 with BDOS 2.2 for the Displaywriter in November 1981, with orders starting to ship in Q1 1982. The release contains custom I/O calls and printer configuration menus for the Displaywriter's proprietary hardware. It is functionally equivalent to CP/M-86 for the IBM PC, but with the caveat that the limitations of the Displaywriter disk subsystem and graphics card prevent HDD support or raster/vector graphics support from being possible. That said, most CP/M-86 software is compatible. Due to the wide variety of hardware architectures that ran CP/M, most CP/M-86 software has a keyboard and CRT control code configuration menu, where the appropriate information can be entered for the Displaywriter. CP/M-86 was originally meant to be released under contract, similar to UCSD p-System, but this ultimately fell through, and the operating system was instead offered independently by Digital Research.[14] Reflective of the failed agreement, the independent product revisions were classified as "Maintenance Levels" which is an IBM internal term denoting software revisions, and is not a term used in other Digital Research products. While the internal data stream of the Displaywriter is EBCDIC, the Displaywriter was already fully capable of translating the data stream into displayable ASCII outputs as part of the features of the Textpack software. This functionality was used to run CP/M-86 in ASCII mode. The prerelease version of CP/M-86 had a manually mapped keyboard, but the production release utilized the keyboard IDs produced by the Displaywriter keyboard controller and was capable of switching between keyboard layouts within the setup menu. CCP/M-86 with BDOS 3.1 for Displaywriter also began development in Q4 1981 but was never offered as an official product. Only a prerelease build is available today.

MS-DOS version 1.25 was offered independently by CompuSystems out of South Carolina. Due to the limitations of MS-DOS version 1.25 and the Displaywriter hardware, the scope of applications that can be run is hampered significantly. The release is otherwise similar to MS-DOS 1.25 OEMs done for other systems of the era. The "MS-DOS Loader" written by CompuSystems ignores the Displaywriter's ROM BAT results and does its own hardware assessment when loading the operating system. Printer support is included through Ctrl-P but DOS assumes that the printer is a tractor-fed 5218.

The physical layout of the system electronics unit, which is the box that the CRT mounts to, consists of a power supply on one half, and cards containing different functions slotted into a backplane with six slots, labeled A-F, that IBM referred to as the system distribution board on the other half. The system distribution board has no logic or components of its own. Instead, each of the cards that are inserted utilize the distribution board as an extension of the system bus. The "system card", which is inserted into slot B of the distribution board, contains most of the functions that would be expected on a PC mainboard, including: clock, processor, ROS (ROM), keyboard adapter, interrupt controller and direct memory access controller. However, RAM is not part of the system card and is instead attached as a discrete card in slot E and in some cases also slot F. The disk controller is not located within the electronics unit at all and is instead located within the unit containing the floppy disk drives. Additionally, with some communications configurations, the communications adapter is also located inside the floppy drive unit. These two things necessitated the extension of the system bus outside of the electronics unit through a cable to the drive unit. There is an additional connector on the reverse side of the system card that facilitates this. Slot A on the distribution card will contain the communications card when it is not located in the disk unit. Slot C will contain a feature card and slot D always contains the display adapter card.

The Displaywriter contained, at the time, extensive self test features that were stored in ROS (ROM) chips on the "system card"

While proprietary, the Displaywriter hardware was meant to be configurable to tailor suit the needs of the organization ordering the machine. ffered multiple configuration options and additional feature cards. Feature cards included: a 3277 emulation card, a 3274/3276 attachment card, a printer sharing card, a single external EIA modem card, a dual external EIA modem card, a X.21 communications card, a local device communications card, an enhanced Chartpack display card and a memory expansion card. Additional configuration options included a 25 or 66 line display, one or two disk drives, 1 sided or 2 sided disk drives, a beamspring (Type A) or Model F (Type B) keyboard, and RAM configurations between 128 and 448 KB.

"A basic system — consisting of a display with a typewriter-like keyboard and a logic unit, a printer and a device to record and read diskettes capable of storing more than 100 pages of average text — cost $7,895 and leased for $275 a month."[1] The basic word-processing software was Textpack E, with simple mail merge; Textpack 2 added support for double-sided disks, networking, spellchecking, and print spooling; Textpack 4 added automatic hyphenation, columns, and more sophisticated merging; and Textpack 6 added automatic footnoting and outlining. Other options included multilingual dictionaries, graphics, and reports.[2]