5 Feb
2006
5 Feb
'06
10:28 p.m.
I have done extensive research on this issue. If you happen to take a
look of the schematic of the mscp scsi project, you know my choice. It
is the plain TTL 7406. I can defend this choice for Qbus. It satisfies
the majority of the requirements, and has work around of the rest.
1. availability, price
2. leak current satisfies requirement (Yes, I measured. 0.25mA
specification is for 30V, not 5V)
3. rise/fall time satisfies requirement (This is the most important factor)
4. drain current work around. use one for single terminated QBUS,
parallel two for double terminated QBUS. (when in parallel, leak
current doubles; but the QBUS tolerance doubles too.)
vax, 9000