Those are NOT DTL chips!
Your looking at CTL logic, which uses a circuit similar to an uncommited
emitter output rather than the
conventional totem-ploe output stage.
There are no drop-in replacements, and you cannot use DTL or TTL parts.
Jay Jaeger wrote:
I have one I am working on -- attached to an HP
2114. The drive spins
up and can seek. The interface cards in the CPU pass their
diagnostics, but the controller is locking up -- looks like a problem
in the state flip flops that control the early part of a command.
Also, my guess is that this one is 1.2MB, not 2.5MB. It has one
fixed platter and one removable platter. It also is exhibiting
head/disk interference ("ting") on unload, but so far doesn't seem to
be damaging anything when it does it (but I am using junk pack, just
in case -- can't tell if the ting is coming from the fixed or
If you want to recover the data, you might consider putting the
platter into an RK05, doing an a/d and capture of the raw data (or
even the bit stream after recovery) from the pack. Might be safer.
The logic in my IOMEC 1802 controller that is unhappy has Fairchild
chips -- not standard 74xx fare. It may well be that they are DTL
(sample markings on one are DT uL909759 7020), which I am currently
guessing is a 9097 chip.
At 11:11 AM 8/26/2003 -0500, Tom Uban wrote:
Is there any chance that someone has an Iomec removable platter
disk drive? The type that I am looking for uses an IBM 2315 style
2.5Mb cartridge, similar to an RK05.
I know that this is a pretty futile request, but it never hurts
Jay R. Jaeger The Computer Collection