TRS-80 Model 100

The TRS-80 Model 100 is a notebook-sized portable computer introduced in April 1983. It was the first commercially successful notebook computer, as well as one of the first notebook computers ever released. It features a keyboard and liquid-crystal display, in a battery-powered package roughly the size and shape of a notepad or large book. The 224-page, spiral-bound User Manual is nearly the same size as the computer itself.
It was made by Kyocera, and originally sold in Japan as the Kyotronic 85. Although a slow seller for Kyocera, the rights to the machine were purchased by Tandy Corporation. The computer was sold through Radio Shack stores in the United States and Canada and affiliated dealers in other countries. It became one of the company's most popular models, with over 6 million units sold worldwide. The Olivetti M-10 and the NEC PC-8201 and PC-8300 were also built on the same Kyocera platform, with some design and hardware differences. It was originally marketed as a Micro Executive Work Station, although the term did not catch on and was eventually dropped.

Specifications

Processor: 8-bit Oki 80C85, CMOS,
Memory: 32 KB ROM; 8, 16, 24, or 32 KB static RAM. Machines with less than 32 KB can be expanded in 8 KB increments of plug-in static RAM modules. An additional 32 KB Option ROM can be installed, for a total of 64 KB of ROM, and the Standard ROM is socket-mounted so is readily replaceable.
Display: 8 lines, 40 characters LCD, twisted nematic monochrome, with 240 by 64 pixel addressable graphics. The screen is reflective, not backlit. The screen was made by Sharp Electronics. The LCD controllers are by Hitachi: HD44102CH column controller ICs and HD44103CH row driver ICs; the HD44102CH's provide the programmable hardware interface to software. The refresh rate is about .
Keyboard: 56 keys, QWERTY layout with full standard spacing, 8 programmable function keys, 4 dedicated command keys, and 4 cursor control keys. These last 16 are tactile "button"-style keys. Almost all keys other than the 16 "button" keys are capable of key rollover, so multi-key combinations can be used.
Peripherals: The basic unit includes: Built-in 300 baud telephone modem, Centronics-compatible parallel printer port, RS-232 serial communication port, barcode reader input, cassette audio tape I/O, real-time clock.
Expansion: System bus interface DIP socket.
Dimensions:, weight about with batteries
Power supply: Four penlight cells, or external power adapter 6V

The 8K and 24K versions sold for and respectively.
The Model 100 was promoted as being able to run up to 20 hours and maintain memory up to 30 days on a set of four alkaline AA batteries. It could not run from the rechargeable nickel-cadmium batteries available at the time, but a hardware modification was available that made this possible.

Data storage

The computer included a port to connect a cassette audiotape recorder for storage of data and programs. Programs written in BASIC could load and save data and programs to the cassette device. Control was provided to start and stop the tape, but the operator would have to manually put the cassette recorder into "record" or "play" mode as needed.
A popular alternative is the Tandy Portable Disk Drive, introduced in late 1985, an RS-232 serial device capable of storing 100 KB of data FM-encoded on a 3.5-inch single-sided double-density diskette; this drive is identical to the Brother FB100 drive for knitting machines. A second version, the TPDD2, can store up to 200 KB.
A Disk/Video Interface expansion box was released in 1984, with one single-sided double-density 180 KB 5-1/4 inch disk drive and a CRT video adapter. This allows the Model 100 to display 40 or 80 column video on an external television set or video monitor. One empty drive bay permits the installation of a second disk drive.
Another popular form of data backup was that of file transfer to a desktop computer, via either the modem connected to a telephone line, or the RS-232 serial port connected to a null modem cable. The built-in TELCOM firmware makes this a convenient option. The TRS-80 Model 4's TRSDOS 6 operating system includes a utility called TAPE100 that uses the Model 4's cassette port to read and write tapes created by a Model 100, the data of which are stored in TRSDOS disk files. Also because TRSDOS 6 included a communications application, the Model 100 proved a popular "peripheral" for the Model 4 customer.
A bar code reader wand was also offered.

ROM firmware

When first switched on, the Model 100 displays a menu of applications and files and the date and time. The ROM firmware-based system boots instantly, and the program that was running when the unit was powered off is ready to use immediately on power-up. Cursor keys are used to navigate the menu and select one of the internal or added application programs, or any data file to be worked upon.
The 32 kilobyte read-only memory of the Model 100 contains the N82 version of the Microsoft BASIC 80 programming language. This is similar to other Microsoft BASICs of the time and includes good support for the hardware features of the machine: pixel addressing of the display, support for the internal modem and serial port, monophonic sound, access to tape and RAM files, support for the real-time clock and the bar code reader, and I/O redirection between the machine's various logical devices. Like previous Microsoft BASIC interpreters, variable names were restricted to two characters and all program lines and subroutines were numbered and not named. However, the default for floating point numbers is double-precision.
The ROM also contains a terminal program, TELCOM; an address/phone book organizer, ADDRSS; a to-do list organizer, SCHEDL; and a simple text editor, TEXT. The TELCOM program allows automation of a login sequence to a remote system under control of the BASIC interpreter. As with other home computers of the era, a vast collection of PEEK and POKE locations were collected by avid hobbyists.
The Model 100 TEXT editor was noticeably slow in execution, especially for fast touch typists. This was due partly to the slow 8085 CPU and due partly to the slow response time of the LCD screen. Often after speed-typing a sentence or two, the user would have to wait several seconds for the computer to "catch up".
A perhaps not well-known but documented feature of TEXT was that it partially supported the WordStar command interface. The supported commands were the cursor movement and character deletion key combinations on the left hand side of the keyboard; the commands for activating Wordstar menus, like the Block menu, were not functional.
Invisible files in the system RAM named "Hayashi" and "Suzuki" commemorate the names of designers Junji Hayashi and Jay Suzuki. Another invisible deleted file named "RickY" refers to Rick Yamashita. The Model 100 firmware was the last Microsoft product that Bill Gates developed personally, along with Suzuki. According to Gates, "part of my nostalgia about this machine is this was the last machine where I wrote a very high percentage of the code in the product".
Added applications and data files are stored in the internal battery-backed RAM; these can be loaded from and stored to an audio cassette tape recorder or external floppy disk drive. Optional ROMs can be installed in the Model 100, providing a range of customized application software. Only one optional ROM can be installed at a time. Some commercial software applications for the Model 100 were also distributed on cassette.
The Model 100 ROM has a Y2K bug; the century displayed on the main menu was hard-coded as "19XX". Workarounds exist for this problem. Since the century of the date is not important for any of the software functions, and the real-time clock hardware in the Model 100 does not have a calendar and requires the day of the week to be set independently of the date, the flaw does not at all impair the usability of the computer; it is cosmetic.

Applications

When introduced, the portability and simplicity of the Model 100 made it attractive to journalists, who could type about 11 pages of text and then transmit it for electronic editing and production using the built-in modem and TELCOM program.
The keyboard is full-size and uses a standard layout; reviewers praised it but reported that it was noisy. To quiet the computer, owners put orthodontic rubber bands under the keys. The computer is otherwise silent when it operates, except for the speaker, and runs for 20 hours on 4 readily available and easily replaceable AA batteries. Data is protected by a built-in rechargeable battery when the AA batteries discharge or are removed for replacement. There are several simple programs available on the Internet for transferring files between a Model 100 and a modern personal computer.
The Model 100 was also used for industrial applications and in science laboratories as a programming terminal for configuration of control systems and instruments. Its compactness, low maintenance needs, lack of air vents, full complement of ports, and easy portability made it very well suited for these applications.
Third-party peripherals for the Model 100 extended its battery life and file storage capacity. Software was designed, and is still available, to extend the display capabilities and to provide more advanced word-processing or calculation software than the supplied programs. To this day, hobbyists continue to design games, applications, and hardware for this device. Simple drawing programs and games using the pixel-addressable display were favorites among users. As with virtually all other contemporary home computers, users are able to create their own applications using the included BASIC programming language. There are no built-in facilities for 8085 assembler programming, but the thoroughly-documented BASIC interpreter by Microsoft offered the clever coder tricks for accessing machine code subroutines. These tricks usually involved packing the raw object code into strings or integer arrays, and would be familiar to veteran programmers for the older TRS-80 Models I and III.