Posted By
SVS
on 2016-01-30
14:56:40
 |  IC 6523 TIA info
Sorry for this very tech question, but anyone can check this info regarding an IC of our loved 1551 drive?
PORT C bit 4 (R/W head)
bit=1 means Write or Read mode?
I ask for this because I've found conflicting information in 2 docs.
Many thanks!
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Posted By
gerliczer
on 2016-01-31
10:14:02
| Re: IC 6523 TIA info
The mainboard drawing shows that it is connected to the Output Enable signal of the U6 Gate Array. Which in turn is connected mostly to the U11 Hybrid IC. That controls not only the R/W head but also the stepper motor. I think this means that the gate array initiated state changes of the hybrid will occur when this line is raised to high. Which is not limited to selecting reading or writing mode. I hope somebody actually knowing 1551s could confirm or deny this.
What are the conflicting information sources?
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Posted By
SVS
on 2016-02-01
06:11:56
| Re: IC 6523 TIA info
I've found a html-document named "Retró rovat VI: Újra egy „kerregő”, a változatosság kedvéért" then in Hungarian language. It was difficult to understand, but now I've just performed a new better translation. Actually it is said the bit=0 stands for head writing. The same is stated in the TIA Description by Gaia.
Then, if you confirm, I'll take the info as verified. Thank you.
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Posted By
Chicken
on 2016-02-01
03:33:54
 | Re: IC 6523 TIA info
I can confirm that the information in Gaia's document is correct. Back in the days I got my information from a different source, though. Probably, it was some document by Michael Stiller.
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