IBM Displaywriter System
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 Announced on June 17, 1980 and effectively withdrawn from marketing on July 2, 1986, the system was sold with a 5 MHz Intel 8086, 128 KB to 448 KB of RAM, a swivel-mounted monochrome CRT monitor, a detached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.
Software & Operating Systems
Textpack
Textpack is a proprietary word processing suite developed by IBM specifically for the Displaywriter that was aimed at document creation, pagination and finalization. Though this software bootstraps the system and is capable of limited multi-tasking, Textpack is not a general purpose operating system like DOS or CP/M. Instead, it IPLs 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.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 advertised 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. 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. The format that Textpack diskettes utilized, though similar to the IBM 3740 Data Entry System, was unique and not interchangeable with any other IBM system, including the Displaywriter's predecessor, the Office System 6. Text created in Textpack 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 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. This can be done 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 characters stored as EBCDIC on the disk into ASCII before transmitting and vice versa after receiving ta 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. ASCII control characters can be accessed at any time, even in EBCDIC mode, by depressing the control key, and then pressing a corresponding key in the alphanumeric block. Because they are command characters, they do not have associated visuals and don't add to the 256 displayable character total. 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.
UCSD p-System
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 choose 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 and Softech Microsystems also sold a software upgrade that would provide p-System with the appropriate I/O calls for the RS232 port 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 ship many units for the Displaywriter, but was notably used by the USDA Rural Development as the operating system for the "Farmer Program Servicing Action System", 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", which was an advanced version of Reportpack that included financial modeling and easier report generation, "QUICKSTART Utility", which decreased load time of large programs, and "Money-Track" financial tracking by Pacific Data Systems.
CP/M-86
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 mostly functionally equivalent to other CP/M-86 v1.1 implementations, 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. 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 ROS contains a ASCII character translation table which is leveraged in the Textpack software. This functionality was also 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
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 limited. 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. Limited printer support is included through but DOS assumes that the printer is a tractor-fed 5218 and there is no utility to change this default.IBM List of Official Software Offerings
Hardware and ROS Embedded Programs
The Displaywriter, though often compared to the IBM 5150, was quite different internally. The Displaywriter did not use off the shelf components, an open architecture, or third party peripherals. The electronic components bear a physical resemblance to IBM's enterprise level hardware of the era, and in fact many components have been recycled from other systems, such as certain IBM-branded chips, the monitor, the diskette drives, and the keyboard.Electronics Unit
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 is passive and 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, central processor, ROS, 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 a blue berg 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 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 and offered 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, an 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 or Model F 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 and leased for a month."