Tandy/Radio Shack Advert - 18th August 1983

Proving that sometimes the same model can live on seemingly for ever, at least in name, is this advert for the TRS-80 Model 4.

The original TRS-80, one of the "1977 Trinity", had been launched six years before, and this model bears little resemblance to it in the same way that a Mk. 4 Vauxhall Astra is nothing like the awesome Mk. 1.

Although it was aimed more a the business market (into which the IBM PC had been launched in 1981), the amount of memory available on the basic model is still only 16K, and it was still running 1976's 8-bit Z80A processor.

Mind you, the IBM it was up against only provided between 16K and 256K and had a 4.77MHz Intel 8088, which was a 16-bit chip internally but only had an 8-bit data bus.

There was also a "conversion kit" available, which enabled Model 2 disk-system owners to upgrade their old box to a model 4.

The TRS-80 family in 1981, showing the Marks I, II and III, plus the TRS-80 Pocket Computer

During this period, some commentators suggested that Tandy seemed to be producing a new machine every week. In fact in the same week as this advert, Tandy's TRS-80 Model 12 was already in the shops.

The Model 12 was a "sub-IBM PC-class" machine with 80K RAM, one or two built-in 1.25Mb floppy disk drives and a detachable keyboard. With two floppy drives it cost £2,999 (about £13,200 in 2025).

Adding a 12Mb hard disk added the same again, i.e. another £2,999 giving a total in 2025 money of £26,500^[1].

One of Tandy's selling points for the Model 4 was its natural progression from the Model III, as it would still run all the software for the earlier machine.

This was essential given the extensive software base of the earlier models - in particular the Model III - with reports in the US press suggesting that Tandy was the biggest vendor of business software for microcomputers, by a large margin.

It was also planning to offer support for CP/M, and so reckoned that the Model III owners could upgrade without losing any of their current software and in doing so would gain access to thousands of CP/M applications.

Reviewing the Model 4 in Personal Computer News, Nigel Cross wasn't convinced by this argument, saying:

"To be fair, I expected much more from a new Tandy machine - especially with the obvious success of its portable Model 100. But the Model 4 does fit the philosophy of business-oriented hardware that runs all current Model III software. This is a selling point but the business person looking to replace an old Model III shouldn't fall for this. It's like trading in an old but reliable and trusted car for a new one that's a different colour and has a couple of bells and whistles. But for the prospective first-time buyer, the Model 4 is well worth adding to your shortlist^[2]".