• Tag Archives TRS-80 Model I

  • TRS-80 Model I

    Posted on by Azrael Comment

    Tandy Radio Shack – 80 Home computer

    TRS-80

    http://darth-azrael.tumblr.com/post/163450055879/retrobear-tandy-radio-shack-80-home-computer

    The TRS-80 Model I (originally just called the TRS-80) was Radio Shack’s first computer. Introduced in 1977, it was one of the earliest home computers. It competed with the Commodore PET and Apple II as well as the Atari 400/800 all of which were introduced around the same time frame. The TRS-80 was based on the Zilog Z80 CPU and originally shipped with just 4K of RAM though it was expandable to 48K. Most other home computers at that time were based on the 6502 processor.

    The TRS-80 enjoyed a brief period of domination as it was the best selling computer, outselling Commodore and Apple, through 1981. It also had the largest selection of software during that time period. In 1980 it was selling at a rate triple that of Apple who was in second place. After 1981, the TRS-80’s dominance faded as cheaper and graphically more sophisticated computers like the VIC-20 arrived and Apple started gaining a greater foothold. The TRS-80 had a disadvantage in that it did not support color graphics or much in the way of graphics at all beyond basic text. Oddly, at a time when most computers had 40-column displays or perhaps 80-column displays with an upgrade, the TRS-80 had a 64-column display. In addition to TR-DOS, the TRS-80 could also run CP/M but only with modifications.

    A cassette tape drive was included with the TRS-80 to save an load programs. However, it was slow and unreliable. It was difficult to adjust the volume settings correctly for saving and it was often a process of trial and error. In order to add any other hardware, including a disk drive, real-time clock, serial port or even a printer, an Expansion Interface box had to be purchased along with the appropriate expansion card. The Expansion Interface (E/I) box is the box the monitor is sitting on in the picture above. The Expansion Interface box included a floppy disk controller. A single density, 85Kb floppy drive became available about six months after the TRS-80 was introduced. This was also initially unreliable, largely due to buggy TRS-80 ROM code but could be compensated for. More capable third party drives eventually became available as did a hard drive but it was extremely expensive at nearly $2500 for 5MB. A second 5MB drive could be added to the hard drive chassis for an additional $2000. The hard drive chassis could hold up to four drives for a whopping 20 MB at a bargain price of $8500.

    Despite Radio Shack’s mostly low quality software, there were a large number of third party titles available that were much better. For a long time, Radio Shack refused to sell any software it did not develop and this probably contributed the the TRS-80’s fall from domination over the years. Despite note having much in the way of graphical capabilities, there were a number of games (including Zork!) available in addition to productivity and other types of software.

    The TRS-80 was succeeded in 1980 by the Model III (the Model II was a completely different non-compatible business oriented machine) and in 1984 by the Model 4. There was also a luggable version (4P) and finally in 1985 the 4D was introduced. This was the last TRS-80 computer and was available all the way through 1991.





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  • Infocom (1983)

    Posted on by Azrael Comment

    Infocom advertisement from the October 1983 issue of Family Computing

    family_computing_issue-02_1983_oct-111

    Source: Family Computing – Issue Number 2 – October 1983



    Infocom was one of the first major publishers of games for home computers. They are most famous for their text adventures or interactive fiction. That reputation began with their very first game, Zork. However, Zork did not get it’s start on home computers. It was first written for a mainframe.

    In 1977, after having seen Colossal Cave Adventure (‘Adventure’ for short), the very first interactive fiction game, a group of MIT students decided to create their own game. Zork was written in MDL (a Lisp derivative) and given away for free, though you had to have access to a mainframe like the PDP-10 is was written on or the DEC TOPS-20 it was ported to.

    Not too long after, the home computer industry started to take off with computers like the TRS-80 and Apple II being introduced. Naturally, they had the bright idea to turn Zork into a commercial product and Infocom was born in 1979. The major challenge was reducing the 1 MB + program designed for a mainframe to something that could run on a less powerful computer with significantly less memory (32 KB or less). There was also the issue of Zork being written in a language not really suited to home computers at the time. But there was a solution…

    Instead of porting Zork to many computers using machine language, the developers of Zork created a kind of virtual machine or interpreter that could process a reduced version of MDL that became known as ZIL or Zork Implementation Lanuguage. This virtual machine would become known as the Z-machine. An interpreter still had to be written for each machine but this was simpler and had the advantage of making future games based on ZIL instantly portable to every machine with a ZIL interpreter.

    Zork was still too large for home computers of the time so it was ultimately reduced to something smaller. However, the sequels Zork II and Zork III would provide the content that was initially cut. Many other ZIL based games would follow over the next decade. There were ultimately 8 versions of the Z-Machine with later versions supporting graphics as well as text. Modern Z-Machine implementations exist today so with the appropriate data files, all of these games can still be played.

    Interactive fiction isn’t as in vogue as it once was but everyone should give it a try at least once. You might as well start with Zork, the game that started it all.

    The above ad is from the October 1983 issue of Family Computing and features many of Infocom’s releases up to that point.


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