EMULATION
Running the classic Tandy TRS-80
Les Pounder travels back in time to when Doctor Who had a mop of curly hair and a trio of computers ruled our homes.
Credit: http://48k.ca/trs80gp.html
OUR EXPERT
Les Pounder is associate editor at Tom’s Hardware and a freelance maker. He has worked with the Raspberry Pi Foundation and he blogs about hacks and makes at bigl.es.
QUICK TIP
The INPUT keyword can only be used in a program and not directly at the interpreter. We found this out after far too much Googling.
If you want to use the INPUT keyword, or test out an idea, make sure that the line starts with a number (100,200, etc).
L ooking back, 1977 was a pretty good year. We had the space shuttle Enterprise being put through its paces, a plucky farm boy single-handedly destroyed a moonshaped space station and learnt about space wizards, and we had a trio of excellent home computers.
We’ve already covered the first two machines in that trio – the Commodore PET and Apple II – in previous issues of Linux Format, but the final machine, the Tandy TRS-80 isn’t a machine that most UK readers will have had the chance to use. Nonetheless the Tandy TRS-80 was a big deal in its native US market. It was released on 3 August 1977 and it was sold via Radio Shack (TRS actually refers to Tandy Radio Shack) for approximately $399. In 2021 the price would be a hefty $1,799 adjusted for inflation! For your money you got a Zilog Z80 CPU running at 1.774MHz, 4KB of RAM and a comfortable QWERTY keyboard. A bundled cassette drive was your gateway to a wondrous world of eight-bit gaming.
The base system was enough for home users and hobbyists to cut their teeth with the burgeoning home computer scene, but Tandy also had a series of upgrades to keep your TRS-80 updated and to add to its annual profits. You could purchase aftermarket RAM upgrades, up to a whopping 48KB (in 16KB packages) and replace the slow and fiddly cassette drive with floppy drives and even a hard drive.
In 1982 the TRS-80 line was the best-selling home computer, eclipsing the popular Apple II that saw only a fifth of the TRS-80 sales. The TRS-80 was later renamed to the TRS-80 Model 1, and we saw the TRS- 80 Model 2 released in October 1979 –a machine that broke compatibility with the original TRS-80. The Model 2 was aimed at small businesses and came with a 4MHz Z80, 32KB RAM and an eight-inch floppy disk drive.
Software for the Model 1 and 3 was unfortunately not compatible with the Model 2, largely because of differing disk formats and system architectures.