14 Feb
1999
14 Feb
'99
3:02 a.m.
<Well . . . I'd make the observation that while the ALTAIR was certainly
<built in the mid 1970's, several of the other machines to which you refer
<were not, not were the "mini-floppy" drives which later became common.
Ok, lets get on the same page.
I built altair serial number 200 in 1975, January to be exact. from there
I can elaborate but I think being there and using/building many allows me
historical accuracy.
<In the mid-'70's, both ribbon cable and IDC connectors were quite costly b
<comparison with up-to-then common labor intensive hand wiring. As the
Gee I posted something to that effect. A quote of mine from the mail you
quoted.
<> Believe it. The cable was hand wired and IDC in the mid '70s was really
<> new, expensive and not quite ready for pimetime. IDC was more an early
<> 80s item brought to the party.
<economies of scale took effect, ribbon and the associated connector
<mechanisms became both cheaper and more reliable, so that, by the time the
More reliable yes, reliable no. Testing at DEC done in the QA labs put the
average IDC connector as decaying contact resistance and sometime outright
failure in the 10-20 insertion/removeal cycles. The more common D25 or D37
connector was usually 5-10 time better in number of operating cycles.
Their conclusion was for external connectors where cables may be
moved/changed often the D9/15/25/37 connectors were far better choice.
For internal cables where likelyhood of being cycled was lower the IDC
connectors were accetable.
<mini-floppies were accepted, the associated ribbon cable hardware was
<firmly intrenched in the market. The plastic (T&B Ansley in this case)
<ribbon cable connectors were not the best available. The old 8" drives ha
<enough signals which were used early in the game that the 50-conductor
<cable became the standard as opposed to the 34-pin, which could easily
<handle the operation of a drive once the later-accepted conventions were i
<place.
minifloppys accetance was in the 77-79 time frame and IDC was used but
considered "cheaping out".
<At the time of the ALTAIR, these conventions were not yet in place.
That's not news to me. If anything I'd suggested that was exactly the
case. I'd seen a great amount to standards (pseudo standards) shift from
mid '70s to the mid 80s. One well known one was the S100 bus itself.
Allison