ISIS (operating system)

Operating System ISIS (Intel System Implementation Supervisor in Supervisor System Implementation Intel) was originally developed by Ken Burgett to Intel under the new management Bill Davidow from 1975 for systems Development their Microprocessor (IMDS) processors 8080/8085, and later adapted as ISIS-II for FDD systems.

It was a mono user and mono task operating system, where communication with the user was similar to that of a terminal. Its user interface is in some ways similar to that of CP/M, even from the point of view of the program interface. ISIS-II was distributed as part of Intel's Microprocessor Development System.

To open files, the program sends the name of the file and a handler is returned. Each device has a name, which is entered between a pair of two points (F0 and F1 for floppy drives, LP for printer, etc.). Each diskette has a single directory with no possibility of subdirectories.

At the level of user commands, the system includes:

Commands of the standard operating system for disk management: IDISK, FORMAT, DIR, COPY, DELETE, RENAME, ATTRIBCommands for software development: PLM80, ASM80, LINK, LOCATE, LIB, OBJHEX, HEXOBJCommands for external debugging in the developed device: DEBUG, SUBMIT.It had two editors, EDIT had support for editing with macros. The file you edit is directly supported by the floppy disk (always creating a .BAK file). The other editor was CREDIT.

From a program there was access to a series of procedures that could be used to carry out certain specific operations of the system, facilitate programming and manage external devices in a unified manner. These included:

Operations on the data contained in the files: OPEN, READ, WRITE, SEEK, RESCAN, CLOSEOperations on directories: DELETE, RENAME, ATTRIBOperations with the console: WHOCON, CONSOL, ERRORLoad of programs and return to the system: LOAD, EXITCharacter transmission operationsTest operations and status changes.

The programs and data of the ISIS-II operating system were not compatible with the format of the most extended CP/M operating system, but the differences were not large and there were methods and simple application programs that made the corresponding conversions.

ISIS-II needed at least 32 kilobytes of RAM, half the maximum address space for the 8080/8085 CPU that was 64 kilobytes. In the MDS-800 and in the Series-II, the Monitor occupied the addresses between F800h and FFFFh in memory. The format of the 8-inch floppy disks was single-sided, 250 KB in simple density (SSSD) coding in FM, or 500 KB for double density (SSDD) encoding in MMFM. ISIS-PDS was incompatible and unique in both software and storage media, reaching 720 KB on 5¼-inch double-sided double density (DSDD) drives in the Intel Personal Development System (iPDS-100).

The ISIS-IV operating system was also incompatible with the previous ones, since it ran on the iMDX-430 Series-IV Network Development System-II.

The languages of Intel ASM80, PLM-80, BASIC-80, COBOL-80 and FORTRAN-80 were available under ISIS-II. ASM86, ASM48 and ASM51 were also available on systems with processors compatible with these assemblers.