Mixsonian Larry


Home Computer

Space Shuttle EnterpriseOn August 12, 1977, the first flight test of the new space shuttle was performed using the prototype shuttle named the Enterprise after the Start Trek TV show space ship by the same name.  I watched the test on the news that night, it was interesting to see the shuttle sitting on top of a Boeing 747 airplane, which show how big the shuttle was.  Many years later I would see the Enterprise up close at the Smithsonian Air and Space museum.

ADM-3a Computer terminalADM-3A computer terminal

By August I had my IMSAI 8080 for a year and I had added an ADM-3A computer terminal which displayed 24 lines of 80 characters which allowed me to run the BASIC computer language and write small programs.   It was a laborious task to do so though, I would have to use the front panel switches to toggle in a fifty line ”bootstrap loader” program.  This small program then would then read in the BASIC system from a cassette tape which then would talk to the ADM-3A computer terminal to type in and run programs.  Programs could then be saved and loaded from cassette tapes.   It all was not very reliable, the BASIC system would hang or crash, reading and writing to cassette tapes was very awkward and unreliable.  But I had great fun with my own computer at home. 

In August MITS started shipping the DOS operating system for the Altair 8800 computer and IMSA offered the CP/M operating system for my IMSAI computer.  The only problem was it required a floppy disk to run but my friend Charlie, the Harris technician who got the job in Melbourne, found a deal on a dual 8 inch floppy drive for only $600 and we both bought one, him for his Altai and me for my IMSAI 8080.  The floppy disk and CP/M operating system made a huge difference in what I could do with my computer.   Now all I had to do was use the front panel switches to enter the start address of the bootstrap program on the floppy disk controller, put the CP/M disk in the drive, hit start and it would load the CP/M operating system from the disk.  How cool was that!   With CP/M I could then load BASIC from another floppy disk, the even better could load and save programs to floppy disks.  Floppy disks had come down in price to $8 (equivalent to $33 today. The floppy disk unit could read and write the newer “double density”  disks which could hold a whopping 256 kilobytes.  I could store a dozen or more BASIC programs on a single disk.

8 inch floppy disk

Updated: 03-19-2023