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Tuesday, July 20, 2004

What is the difference between Model 4 and Model 4D

Many have asked us "What is the difference between a Model 4 and a Model 4D.  The only difference is that the Model 4 D was the last TRS-80 Radio Shack manufactured so it will always have a green screen (green letters on a dark grey backgound. And it has double-sided double density full height disk drives that will hold 360K of storage space.
If you remove the black face plate you will find that the drives are half height. You can replace these original drives with any half height 5.25" double-density disk drive.
Adding double side drives to any Model 4 will give you a computer that is the same as a Model 4D 


Anonymous jan80trs said...

This answer is correct, but not complete. The 4D was an evolution of the model 4 gate-array. These two had the serial port and FDC build into the motherboard. The 4D had clustered arrow keys, the 4 GA did not. The nameplate of the 4D said 'TANDY', but the older 4 was still a 'TRS-80'.

But before that came the first model 4. Just like the III, the 4 (non-gate array) had the FDC and the serial port on 2 different cards. From the front, the 4 and the 4 (GA) were indistinguishable. You had to look at the back to see the architectural differences.

The setup with 3 cards made the first 4 and the III a bit more vulnerable to connection defects. As a collector of TRS-80's, I can confirm that. The 4 was sold in Europe with a green screen. The 4D never made it here.

4:17 PM  

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