HP-85A tape drive conversion

[Rik Bos]

> -----Oorspronkelijk bericht-----
> Van: cctalk [mailto:cctalk-bounces at classiccmp.org] Namens Jay West
> Verzonden: dinsdag 31 maart 2015 23:17
> Aan: 'General Discussion: On-Topic and Off-Topic Posts'
> Onderwerp: RE: HP-85A tape drive conversion
> 
> When I get a "round-tuit", I'll check what the arrangement is for the 264X
> terminal built-in tape drive. Perhaps they used a similar mechanism to the
HP-
> 85A and it could work with dc2000 tapes (after mod) as well.
> 
> J

The drive mechanism is the same as the ones used in the HP 9825 / 15 / 31 /
35 and 9845 . But this type of drive has issues about the running off the
tape every once in a while.
Somehow the tape end detection not always detects the end of a DC2000 etc.. 
It suspect the tape controller hardware, but I didn't researched it so it's
for the best an educated guess.
The internal controllers of the HP 9845 and 35 have an internal tape counter
which gives an error when the tape is too long, so you can't initialize
DC2000 tapes on a 9845 and 35.
I've modified the drives in my 264X terminal but got no further than a basic
test run, because the DMA card of my terminal doesn't function right and
I've a small shortage of time ;)
The tape speed of those terminals as almost twice the speed of a HP-85.Could
also be a problem because the DC2000 tapes are wider and should have more
head friction.
May be I should pull the thing out of storage and look if I can get it
working.

-Rik