From: Bryan Pope (bpope_at_wordstock.com)
Date: 2007-03-21 00:50:08
And thusly were the wise words spake by email@example.com > > > Is there a webpage that describes how to measure the I/O signals? > > Have a look at the NRFD (Not Ready For Data) signal first. This signal > tells the computer that the drive is not able to receive data at all at > this moment. So have a look at this signal first: (L) means active and > the computer will wait until it is (H). So if it is (L) indeed, check > the level all the way up to the I/O ICs in both the drive and computer. > Ruud, A logic probe is also in my order from Jameco. Once I get that (next week) I will check what you said. > I read you replaced a 6522. In the drive or the computer? I had a > similar case and here the troubleshooter was the 6522 in the computer. > It was in the drive, from another working one. I was going by the 2031 troubleshooting guide on zimmers.net which said if it locks up while loading check the IEEE interface components and the ROM. Another section (page-12l) titled "IEEE Interface" says all of the signals are controlled by device U3H (the 6522 I tried swapping) plus U1S (75160) and U1A (75161). Hopefully I was going in the right direction! Thanks!, Bryan Message was sent through the cbm-hackers mailing list
Archive generated by hypermail pre-2.1.8.