TRS-80 Model III (Tandy/Radio Shack TRS-80 Model III)
John Freire came by the DigiBarn in December 2004 bringing this wonderful donation, a sterling TRS-80 Model III (3) which was converted into a Model IV (4) by Radio Shack for him. Indeed this is a very early Model III (number 133) but it has internals of the Model IV (more RAM etc) but retains the silver color of the III (the IV was white).
Commentary by DigiBarn Curator Bruce Damer
I remember seeing this silver baby at our college when I started in computers in 1981 but it was only accessible to the system operators of our PDP-11/34 (I was jealous). It seemed to be a real computer with the built in keyboard and floppies. The DigiBarn's Model III is a relatively rare unit in that it does not have floppy drives. I was told that this was an option. I am not sure how useful this would make the unit but perhaps it was operating with built-in ROM BASIC.
The Model 3 was Tandy's second personal computer. One of the reasons it was developed was because the FCC instituted regulations about the RF emissions generated by computers (and other electronic devices). The Model 1 was completely unshielded (a fact many owners who also like TV and/or radio discovered the hard way), and was unable to pass the emission restrictions.
The Model 3 was somewhat better for new users because the monitor and keyboard were all in one unit. That got rid of the problems the Model 1 had with funky connections between the keyboard and expansion interface. The serial port was also usable. :-) The cassette interface supported both the 500 baud speed of the Model 1, as well as a much faster 1500 baud. Using a cassette based system was much less painful with the data screaming along at that speed.
The Model 3's BASIC ROM was 2k larger (at 14k) than the Model 1, added the 1500 baud cassette speed, allowed for left and right shift keys to be at separate addresses in the keyboard memory area, and added a 25 or 30 HZ real time clock routine (country dependent) which allowed for TIME$ to be added to ROM BASIC.
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