ISO Intertec 5.25" floppy drive jumper settings
cisin at xenosoft.com
Sun Dec 2 17:32:47 CST 2018
On Sun, 2 Dec 2018, Adrian Graham via cctalk wrote:
> In my long ongoing quest to image and otherwise copy the hard sectored
> floppies with my Exidy Sorcerer I’m trying to find other floppy drives
> I can use with it since I don’t like relying on just one set of
> drives. I have a Cumana dual drive set that came with my TRS80 Model1
> that I thought might be jumperable to 300rpm, indeed I can see drive
> activity if I try and boot.
If those were being used on a TRS80 Model1, then they are already 300RPM.
> Does anyone know where I might find the/a manual for the drives?
> They’re marked as Intertec 5002040 so I’ve been all over Superbrain
> docs and PDFs on bitsavers but haven’t found anything so far.
If they were used on a Superbrain, then they are already 300RPM.
But, Be VERY careful with Superbrain documentation and [mis]"information".
They started off with an ordinary 200K 40 track MFM SSDD / Single Sided
Double Density 48tpi. (Like the PC-DOS 160K/180K)
When they went to 400K 40 cylinder MFM DSDD / double sided, double
density, still 48 tpi (like the PC-DOS 360K), they chose to call that
"QD" / "QUAD DENSITY"!! ?!?? (equating "density" with capacity)
WHOA! Everybody else called THAT DSDD "Double Sided Double Density", and
used "QD" / "Quad Density" to refer to 80 cylinder Double density 96tpi!
So, when you see mention of Superbrain "QUAD DENSITY", they are referring
to a drive like the PC 360K! NOT what anybody else called "QUAD
Mentions of "80 track" don't help, because that could be referring to 80
tracks made up of 40 tracks per side (40 sylinders), OR be referring to 80
tracks per side.
When Superbrain went to 800K 96tpi Double Density (which everybody else
was calling "Quad Density", Superbrain called THAT "SUPER Density", which
they abbreviated "SD".
YES, they really did call their 800K format "SD"!
Q [Rhetorical]: What did "SD" mean to anybody else?
Superbrain's disk format was 10 sectors per track (numbered 1h through
0Ah), with 512 bytes per sector. The Address marks are pretty "normal",
althought 10 sectors per track can sometimes pose difficulties on NEC
controllers, but the data field in each sector is inverted. And, if I
recall correctly, they used an INCORRECT value in the "Head Number" field
on the sectors on the second side, but would accept disks with correct
I have heard that they used a Z80 for floppy control, but the disks are
consistent with a Western Digital 179x controller.
I doubt that they manufactured their own disk drives, but it is possible.
Look carefully at the drives for any hints of who actually made them.
Are these "full height" (SA400) or "half height"?
I had not heard of Cumana. Google says that it was a British company
(Guildford) peddling disk drives in their own cases, mostly for BBC and
Various forum posts describe Shugart 465 (96tpi), and Mitsubishi 4853
(96tpi) One on eBay looks like a Mitsubishi.
Grumpy Ol' Fred cisin at xenosoft.com
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