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, which compares very favourably to disk-based computers. Not only is the machine ready to use immediately on power-up, but it will also continue running, from the same point, the program that was running when the unit was powered off. 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 files, and support for the real-time clock and the bar code reader. Unlike other Microsoft BASIC interpreters of the time, 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.
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.
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.
Read more about this topic: TRS-80 Model 100