971018 - Differential Story
Back in 1997, hard drives were not so cheap here in Japan. New hard drive
of 1G capacity costs about JY10,000. As a matter of fact I could not pay such
money for SCSI hard drives. According to my master of MCA, used 5" full height
drives were relatively cheap to get. He wrote that he sometimes got 1G drive
for JY1,000 in used PC market. OK, that was the way I liked.
As usually, trolled around junk shops. Found three ST42400ND at a shop. A
clerk said they were defective and their testing system could not detect them.
I had taught by the master of MCA that the last letter "D" in Seagate drive
meant "Differential". Paid JY3,000 for three drives. Ordered Rancho
single-differential converter to US hi-techinc.com (it cost me another
JY5,000, MAD level increased one step higher).
Nov. date unknown
Got single-differential converters from hi-tech inc. One was Rancho's
converter and the other was labeled as "Juke Box". Rancho converter could be
used in bi-directional, from differential drive to single-ended usual adapter
and/or from single -ended drive to differential adapter. Juke Box is a tiny
card to be connected to differential hard drive directly.
Opened up my "Grandma", connected the Rancho off from short cached SCSI 2/A
with yellow DIP terminator (of course the terminator was pulled off) after the
small IML drive, and then connected a ST42400ND to Rancho differential end.
Hey-ho, 2G capacity would be provided for me with Rancho converter. "Power
on!", pushed the main SW. "Go baby go, go. Go
baby go go...?" Charming error code was displayed
on the LED panel (don't remember it). Tried various combination of jumper
blocks on the Rancho card. No lucks... Pulled off the Rancho card and powered
SCSI drive was not detected by the system. 5580 warned me that Spock SCSI is
The short, cached SCSI /A that I used for the test was known to be capable
to handle IML drive >1G. And that was the only one I had back then. I had not
yet tried it with a usual single-ended narrow drive larger than 1G (because I
had not such a drive. All of my 3.5" SCSI drives were below 500MB). Yes I had
some of bigger drives but they were all 5" full height shape made of DEC,
Micropolise and Fujitsu. What the h*ll happened there. I examined short Spock
to every inch with my ohm meter and found that a very little black square chip
was defective. Same part used in 16bit SCSI card had electrical connection
(sorry I don't know how to say call it) between both end, but the one in 32bit
Spock had no connections. A needle of my ohm meter deflected outer ward. The
part might was supposed to be a FUSE with it's silk marking "F1". What kind of
fuse it was? I asked to the Forum and got an answer that it might be a part so
called "polyswitch". Few days latter I got similar kind of tiny chip and used
it to replace the burnt one. Bingo! Specification of the chip I bought was
bit different from original part but it was functional and revived my precious
Oh, well, I should talk about Rancho. As a matter of fact I don't remember
how I got rid out of the trouble. But Rancho converter securely drove
ST42400NDs. It had been sat in my 5580 for about 3 years with a ST42400ND. I
also got some differential drives latter. HP, Sequant (probably HP OEM) and
Seagate. Most of them were donated to used PC Parts forum.
Someday in 2000, I happened to see funny drive cages pulled off from
unknown server machine at a garage shop. I could just recognize markings "IBM",
"DFxx" through punching holes of the cage. They were not slim height drives so
I assumed they should be DFHS S4F (Single Ended 50pin Fast) or S4F (Single
Ended 68-pin Fast/Wide). I Paid JY3.000 for 3 assembly of cages and drives.
Back at home, disassembled the cages, saw the labels on the drives saying "DFHS
S4E" Grrr... they were actually First/Wide drives
Read message by Dan that he wanted to sell differential corvette. The part
number was same with the one supposed to be functional on PS/2 (according to
Louis' page). Paid for it through PayPal. Received a
Differential First Wide SCSI II /A.
I'm ashamed. I have not yet checked it to drive DFHS S4Es in my 95.
Japanese Lesson #1
go go: "5" is "go" in Japanese. "55" is
"gojyu-go" (say, 10 is "jyuu").
Mathematically "55" should be pronounced as "gojyuu-go".
I usually call it as "PS go-go"
I don't know how IBM called PS/55, PS fifty five, PS gojyuu-go, PS go-go...
But anyway... Go baby go, go. GO baby go go go go. Jophny B. Good...
I bet Sony PlayStation will never reach to "55" and PS/55 will always be
high above from it.