So, I finally tore down my Tandy 6000 to figure out why the video was no longer working. In the end, it turned out to be the Z80 went bad. As you may know, to get at the cpu in the 6000 you need to take the machine completely apart..a real PITA which is why I waited so long to do this, I guess. Anyway, what I found interesting is that the Z80 was not a Zilog part. It was an SGS from Italy. The DMA chip was also an SGS part. I hadn't seen these used before in a TRS-80.
IMG_2422.jpg
I replaced the Z80 with a Zilog unit from a parted out Model II and now the 6000 runs fine.
I know SGS was an second source manufacturer for the Z80. But, I'm wondering if these are sub-standard? This 6000 had very few miles on it as it is in like-new condition. It's also a very late model 6000. It's well known that Tandy would save a buck wherever possible so I wonder if these were a cheaper alternative to a real Zilog.
IMG_2422.jpg
I replaced the Z80 with a Zilog unit from a parted out Model II and now the 6000 runs fine.
I know SGS was an second source manufacturer for the Z80. But, I'm wondering if these are sub-standard? This 6000 had very few miles on it as it is in like-new condition. It's also a very late model 6000. It's well known that Tandy would save a buck wherever possible so I wonder if these were a cheaper alternative to a real Zilog.