Model M Screen Reader Keypad

The IBM Screen Reader Keypad ("SRK") was an 18-key function keypad that was the peripheral component of the IBM Screen Reader series, first announced in January 1988. The IBM Screen Reader was a part of the IBM Independence Series product range^[1][1]
IBM - The IBM PC's debut details - The first 10 years [accessed 2022-09-24]. and on introduction a pioneering screen reader designed to help people with hard or lack of sight access a PC. Whilst this keypad is erroneously solely attributed and named after the IBM Screen Reader/2 that was released as late as June 1992^[2][2]
IBM - IBM Screen Reader/2 Brief Description of Announcement, Charges, and Availability (#292-363) [accessed 2023-03-07]., the Screen Reader Keypad was actually introduced with Screen Reader 1.0 and was included with versions 1.1, Screen Reader/DOS series and finally Screen Reader/2 series without any modification to the keypad design. The Screen Reader Keypad is a part of the large IBM Model M keyboard family and is currently its second smallest known member than uses IBM's famed buckling spring clicky key-switches behind only the Model M15 Numeric Keypad Option. It's a very dense device and in fact shares numerous IBM Model F esque internal design traits as the keypad is in fact related to the IBM 3290-1/5080 Numeric and Program Function Keypads. Only one part number is known - P/N 1393387, FRU 1393515, feature code 2549. The Screen Reader Keypad was withdrawn from marketing on 28th April 1995 and replaced by a new keypad with an integrated cable (P/N 06H5990)^[3][3]
IBM - Withdrawal: IBM Screen Reader Keypad and Cable -- Replacement Available (#195-112) [accessed 2023-03-08]..

Contents

Summary

History

Work for what would become the IBM Screen Reader began in 1984 as a project for an 'audio access system' by Jim Thatcher, a then mathematician working at IBM^[4][4]
American Foundation for the Blind - A History of Accessibility at IBM [accessed 2023-03-06].. Simultaneously on 26th January 1988, the IBM Screen Reader Keypad's application for grant of equipment authorisation was registered with the FCC^[5][5]
FCCID.io - International Business Machines Corporation 9SA6450602 [accessed 2023-03-06]. and its host IBM Personal System/2 Screen Reader package (P/N 6450602) was announced, slated for availability on 18th March 1988. This version 1.0 of IBM PS/2 Screen Reader was touted as enabling "the blind or visually impaired computer user to "hear" the display as the sighted computer user "sees" it" and packed the 18-key Screen Reader Keypad (P/N 1393515, feature code 2549), Screen Reader Keypad Cable (P/N 72X8537, feature code 2550, 6-pin SDL to PS/2 mini-DIN), complimentary software, and documentation^[6][6]
IBM - IBM Customer Announcement Summary - January 26, 1988 (#C88-001) [accessed 2023-03-08].. It was intended for DOS only.

IBM PS/2 Screen Reader v1.0 was withdrawn from marketing effective 15th December 1989^[7][7]
IBM - PS/2 Screen Reader Version 1.0 Withdrawal from Marketing (#289-579) [accessed 2023-03-08]. and replaced with IBM Screen Reader 1.1 ("Personal System/2" was dropped from the name), which was announced on 24th October 1989 and planned availability was slated for the same day v1.0 was withdrawn. v1.1 is upward compatible with v1.0 and the keypad design was unchanged. However, the software was now available in a version for PS/2 (P/N 6450616) and a version for PC/XT and PC/AT compatible PCs (P/N 6450617). The PC version also comes with a Screen Reader Adapter^[8][8]
IBM - Screen Reader Version 1.1 Brief Description of Announcement, Charges, and Availability (#289-578) [accessed 2023-03-08]. (P/N 57F1588, feature code 2551^[9][9]
IBM - IBM Screen Reader/DOS Version 1.2 Brief Description of Announcement, Charges, and Availability (#292-364) [accessed 2023-03-08].), which was an ISA expansion card that added a PS/2 port specifically for the Screen Reader Keypad.

On 23rd June 1992, the Screen Reader line was shaken up again as v1.1 was announced to be replaced with IBM Screen Reader/DOS Version 1.2 and IBM Screen Reader/2 Version 1.0. IBM Screen Reader/DOS is the direct replacement for Screen Reader v1.1 as it's intended for [IBM] DOS only (version 3.3 or later) and follows the previous release's version nomenclature. It was made available on 30th June 1992 and continued recommending the same hardware components^[9][9]
IBM - IBM Screen Reader/DOS Version 1.2 Brief Description of Announcement, Charges, and Availability (#292-364) [accessed 2023-03-08].. Like the original product, IBM Screen Reader/2 was developed under Jim Thatcher and was the first screen reader for a graphical user interface (GUI) on PCs^[4][4]
American Foundation for the Blind - A History of Accessibility at IBM [accessed 2023-03-06].. Screen Reader/2 was intended for use with PS/1 or PS/2 compatible PCs running IBM OS/2 2.0, although it could be used with other systems via the existing Screen Reader Adapter. It was made available on 8th September 1992^[2][2]
IBM - IBM Screen Reader/2 Brief Description of Announcement, Charges, and Availability (#292-363) [accessed 2023-03-07].. The key difference between Screen Reader/DOS and Screen Reader/2 and earlier releases was that the Screen Reader Keypad, Screen Reader Keypad Cable and Screen Reader Adapter were now technically separate purchases^[10][10]
IBM - IBM Screen Reader Features Brief Description of Announcement, Charges, and Availability (#192-154) [accessed 2023-03-08]..

Screen Reader/2 1.0 would be followed up by versions 1.1 and 1.2 within a year. On 24th August 1993, Screen Reader/2 Version 1.21 was announced that required IBM OS/2 Warp 3.0 and introduced a new keypad (P/N 06H5990) that now has a fixed cable and could be connected to a Serial port, PS/2 mouse port or via the existing Screen Reader Adapter^[11][11]
IBM - IBM Screen Reader/2 Version 1.21 Announcement Letter (#ZP93-0544) [accessed 2023-03-08].. There's presently no surviving evidence of what this keypad looked like and whether it was even Model M based. v1.21 was withdrawn from marketing effective 31st March 1996^[12][12]
IBM - Withdrawal from Marketing - IBM Screen Reader/2 Version 1.2.1 (#A95-1465) [accessed 2023-03-08].. Screen Reader/2 2.0 is believed to be the final release, made available on 1st December 1995 and now supporting OS/2, Windows and DOS in one package^[13][13]
IBM - IBM Screen Reader/2 Version 2.0 Announcement Letter (#A95-1198) [accessed 2023-03-08].. Before this launch, however, the original Screen Reader Keypad and its cable were withdrawn from marketing on 11th April 1995^[3][3]
IBM - Withdrawal: IBM Screen Reader Keypad and Cable -- Replacement Available (#195-112) [accessed 2023-03-08]..

Pricing

Before 23rd June 1992, the Screen Reader Keypad was only purchasable with the entire software package, hence the massive price difference between 1989 and 1992. All inflation adjustments were made with US Inflation Calculator.

Design

Key-switches

More information: IBM buckling spring#IBM membrane-type

The Screen Reader Keypad uses IBM buckling spring over membrane clicky key-switches like most of its contemporary larger siblings. Such a switch is comprised of a coil spring, a rocker (also known as a flipper or hammer, the white piece of plastic visible underneath the springs in the photo above) and the membrane circuitry underneath - pressing down on a buckling spring key causes the coil spring to compress and eventually buckle, which then rocks the flipper attached to the bottom of the spring thus actuating the membranes^[16][16]
IBM - Rocking switch actuator for a low force membrane contact switch [accessed 2021-06-17].. The mechanism rocks the membranes before its fully buckled (bottomed out), allowing for part-way actuation. Key travel is 3.8mm^[17][17]
Unicomp - The Customizer Keyboard [accessed 2022-10-04]. License/note: retrieved via Wayback Machine (2000-06-14 capture)..

Despite the fact it uses the same springs and rockers as other buckling spring Model Ms, differences in the internal assembly design explained below contribute to a different sound profile and feeling to other Model Ms.

Outer case

The Screen Reader Keypad is designed with the same look and feel as a regular Model M of the period, retaining the distinctive wedge-shaped case that facilitates a curved internal assembly that partially swoops up to provide a ledge commonly used to hold items such as pens or pencils. However, compared to the IBM Enhanced Keyboard, the Screen Reader Keypad is overall stubbier. Instead, it uses the same side profile as other small form-factor buckling spring Model Ms such as the IBM Space Saving Keyboard (SSK), IBM PS/2 50-key Function Keyboard, Unicomp New Model M and Unicomp Mini Model M. The case is held together with two 7/32" (~5.5mm) flanged hex-head screws.

The case material used is presently unknown. There are several markings on the inside of both the top and bottom case pieces including "ACM" and "GG7160" that may be significant in regard to the material used. The top case piece part number is 1393425 and the bottom piece part number is 1393424.

Internal assembly

In terms of internal assembly design, the Screen Reader Keypad is quite different to other Model Ms. Whilst it's true it's still a membrane-driven buckling spring keyboard, the assembly (P/N 1393388) that houses the buckling springs is actually derived from Model F design principles. This is because the assembly design is actually derived from the 24/25-key IBM 3290-1/5080 Numeric and Program Function Keypads - in fact, there are disused key positions visible that would have been used for the predecessor keypad's extra keys. The only other Model M-designated keyboard that is similarly designed is the IBM PS/2 50-key Function Keyboard.

A typical Model M keyboard assembly can be summarised as having a plastic universal barrel plate (guide for the buckling spring actuators), a membrane blanket (for dampening stress from the said actuators), the membrane assembly itself (a multi-layer printed circuit) and the backplate (provides rigidity and curvature) that's plastic riveted to the barrel plate with everything else sandwiched inside. Such plastic rivets provide the tension needed for the buckling springs to operate properly, which is the single largest flaw in the typical Model M design as they can weaken and break with age. Instead, the Screen Reader Keypad lacks the membrane blanket completely and has a new layer in its place, and the other layers are different as well.

Keycaps

The Screen Reader Keypad's keycaps are IBM's famed PBT dye-sublimated keycaps. Versus the most common keycap material, ABS^[19][19]
WASD Keyboards - Mechanical Keyboard Guide [accessed 2022-07-01]., PBT is more durable, does not degrade/yellow with age, UV or heat exposure, and will keep its texture for longer without shining^[20][20]
Switch And Click - ABS vs PBT Keycaps: What’s the Difference? [accessed 2021-09-09].. Dye-sublimation is also a very durable text printing method that sinks dye material into the keycap's plastic itself, meaning there is nothing to quickly wear off as would be the case with pad-printing or silk screening. This means these keycaps can remain in good condition for a long time. The dye sublimation quality will be similar to contemporary Model Ms but unique to Screen Reader Keypad is their larger font.

Rear labels

More information: Keyboard Rear Labels topic

Like most Model Ms, the Screen Reader Keypad employs a recognisable rear label (casually referred to as a "birth certificate") both on the back of the outer case and the back of the internal assembly that can be used for identification via a part number and model designation and for dating the device.

External rear label

The rear label on the back of the Screen Reader Keypad is a modification of a standard IBM United States-style rear label. The formatting of the standard data (part number, ID/serial, etc.) remains the same, although an FCC ID surrounded in a black box and an FCC compliance statement underneath it are included. Whilst Lexmark and Unicomp era keyboards could have such information included on the rear label, it's unusual for IBM-manufactured Model Ms to have such detail. The date format is typically DD-MMM-YY or MM-DD-YY.

Internal rear label

If present, the rear label on the back of the Screen Reader Keypad's internal assembly is an IBM United States staple without modification. As such, it has a four-digit internal shop date instead of a real date. Some Screen Reader Keypads lacked any internal rear label, instead having the assembly part number and a real date (MM-DD-YY format) stamped or written on the backplate instead.

Controller

The Screen Reader Keypad's controller card is essentially a small version of the original Enhanced Keyboard controller used during the 1980s. Its part number is 1393368 as per the copper filling on the back of the card. The card has a Hitachi HD6805 series microcontroller (specifically, HD6805V1N12P with IBM part number 1393371). The HD6805V1 series is an NMOS 8-bit MCU running at 1MHz with 96 bytes RAM, 3.838KB RAM and 24 I/O ports and 8 input-only ports^[23][23]
Hitachi - 8-Bit Single-Chip Microcomputer Data Book (#U71) [accessed 2023-03-12]. License/note: document archived by bitsavers.. The membrane assembly connects to the card via two 8-pin 2.54mm pitched Triomate connectors (although one pin on the second connector is not used by the membrane's matrix). The card has a large ground wire that is screwed onto the keypad's assembly's backplate.

Flip-out foot

The Screen Reader Keypad has a single flip-out foot unlike anything used on other Model M keyboards. It's a metal bar that heavily resembles the stabiliser element used on buckling spring Model M spacebars. It appears to have a grey-coloured coating that can wear or flake off.

Layout

The Screen Reader Keypad is not designed as a replacement or alternative to a computer's numeric keypad, hence even the 3x3 number section is different to a typical numpad. The number keys plus the "*", "0" and "#" keys are instead arranged like a United States telephone keypad. Both the "5" and "A" keys have homing bumps for orientation. The "HELP" key was used as a toggle to enter a Help mode in the Screen Reader software. Whilst in this mode, the software would tell you what each key does when you press it. The "STOP" key functioned like a general cancel button within the Screen Reader software and was able to interrupt text-to-speech^[24][24]
IBM - IBM Independence Series Screen Reader/2 Getting Started [accessed 2023-03-12]..

Connectivity

The Screen Reader Keypad is technically a PS/2 compatible device but there are some important considerations. Whilst the form of physical connectivity matched that of most early PS/2 compatible Enhanced Keyboards, the Screen Reader Keypad was actually designed to connect through either a PS/2 compatible PC's mouse port or via an ISA card for early IBM PC compatibles (seen below). As such, this keypad will not provide any meaningful operation through a modern PC's PS/2 keyboard port, an active PS/2 to USB converter or via any PS/2 mouse port without the required software. Until a modern converter has been devised, one would either need to use the keypad for its intended purpose on legacy hardware or replace the controller card with something purpose designed.

The Screen Reader Keypad features a 6-pin modular AMP shielded data link (SDL) port and a detachable cable, a known staple for PC-compatible Model Ms from the 1980s and early 1990s. This allows the keypad to be uncoupled from its cable as needed for storage or easy swapping. The cable was typically a high-quality grey and thick coiled cable, and for the Screen Reader Keypad specifically had a part number of 72X8537. The cable ends with a PS/2 port with a standard pinout, however as aforementioned, the keypad's hardware itself will not support it being used with a PS/2 keyboard port. However, the cable can be used for other SDL-bearing Model Ms and likewise other SDL to PS/2 cables can be used as a substitute for the Screen Reader Keypad's original cable.

For PCs lacking a PS/2 port such as IBM PC/XT and PC/AT compatibles, IBM made an 8-Bit ISA expansion card available that provided a PS/2 port to connect the Screen Reader Keypad with. This card was called the IBM Screen Reader Adapter; P/N 57F1588, assembly P/N 57F1587, FRU 33F4842.

Further reading & resources

Internal

External

Sources

ASK. Admiral Shark's Keyboards original content. License/note: CC BY-NC-SA 4.0.

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