14 Jun
2007
14 Jun
'07
1:58 p.m.
I;ve not looked at it properly yet, but the pinout of
that chip appears
at a glance to be _very_ close to that of the WD1793 (closer to that than
the WD1771, for example). More data when I've done a little tracing.
I have now done that 'little tracing'. As far as I can see, the pinout is
the same as a WD1793. There are some pins pulled high (these would be
Ready, HLT and Test/), and DDEN is tied to ground, but then I'd expect HP
to hard-wire it in MFM mode.
I think I'd first check I was getting a master clock on pin 24 (I think
this should be 1MHz), and then look at pin 26 (read clock) when the unit
was trying to read a floppy.
-tony