I’ve been restoring a RM380 I picked up not long ago and it’s been good news
and bad news. All the cards are in wonderful condition and the case is
presentable however the two BASF 6106 floppy drives are highly corroded and
probably won’t work again but this isn’t what I’m wondering, the origina
On Mon, Feb 27, 2023 at 10:29 AM jake utley via cctalk
wrote:
>
> I’ve been restoring a RM380 I picked up not long ago and it’s been good news
> and bad news. All the cards are in wonderful condition and the case is
> presentable however the two BASF 6106 floppy drives are highly corroded and
>
On Mon, Feb 27, 2023 at 12:06 AM Chuck Guzis via cctalk <
cctalk@classiccmp.org> wrote:
> On 2/26/23 16:42, Chris Zach via cctalk wrote:
> > Oi.
> >
> > So after finally getting things going I started copying the Pro/380 OS
> > files to a bunch of 1.2mb floppies. Great. However after a bit I start
Well, the weekend of hardware sudden death continues. The reason for getting
the UltraBook IIi out was to do some more work on kOpenRay, the free Sun Ray
server software I very occasionally maintain. Among other devices I use(d) two
Accutech Gobi laptops to talk to it since they have an oddball VPN
On 2/27/23 06:50, Warner Losh wrote:
> You should be using QD floppies, but those are rare. DD floppies from
> later than
> 1985 though work just fine (discovered empirically while a poor college
> student,
> reconfirmed recently when I made all those Venix disks).
Speaking from experience and c
On Mon, Feb 27, 2023 at 9:30 AM Chuck Guzis wrote:
> On 2/27/23 06:50, Warner Losh wrote:
>
> > You should be using QD floppies, but those are rare. DD floppies from
> > later than
> > 1985 though work just fine (discovered empirically while a poor college
> > student,
> > reconfirmed recently w
On 2/27/23 09:30, Warner Losh wrote:
>
> Prior to about 1984 or 85, the failure rate for DD floppies for me was
> high enough that I splurged for the QD. After 84 or 85, I never had any
> problems
> using DD media. I suspect that yields must have gotten better, but maybe I
> just had bad luck pri
> On Feb 27, 2023, at 9:50 AM, Warner Losh via cctalk
> wrote:
>
> On Mon, Feb 27, 2023 at 12:06 AM Chuck Guzis via cctalk <
> cctalk@classiccmp.org> wrote:
>
>> ...
>> I thought the Pro 300 series used RX-50 drives; i.e. 400K 96 tpi DD
>> media. So even with your 5.25" HD drive, you shoul
On Mon, 27 Feb 2023, Warner Losh wrote:
You should be using QD floppies, but those are rare. DD floppies from
later than 1985 though work just fine (discovered empirically while a
Are they? I guess that I have at least as many QD floppies as DD, if not
even more. :-)
However, in a PC, to wri
Hi Bob
Thanks - thats very interesting. I guess there was quite a bit of overlap with
the 11 and the 8/A so 'marketing' stepped in :-)
Oh really - what a nightmare :/ - they are rare boards it seems.
On Mon, Feb 27, 2023 at 11:10 AM Christian Corti via cctalk <
cctalk@classiccmp.org> wrote:
> On Mon, 27 Feb 2023, Warner Losh wrote:
> > You should be using QD floppies, but those are rare. DD floppies from
> > later than 1985 though work just fine (discovered empirically while a
>
> Are they? I
On 2/27/2023 12:54 PM, Chuck Guzis via cctalk wrote:
On 2/27/23 09:30, Warner Losh wrote:
Prior to about 1984 or 85, the failure rate for DD floppies for me was
high enough that I splurged for the QD. After 84 or 85, I never had any
problems
using DD media. I suspect that yields must have gott
As already said here most of the better DSDD diskettes could handle 48
or 96 TPI.
The biggest problem I remember from that era (on 6809 Systems in the
early '80s and early PC's) is intermixing 48 and 96 tpi drives and
reading/writing both drives.
Since the tracks are half as wide on the 96 T
> On Feb 27, 2023, at 10:21 AM, Mike Katz via cctalk
> wrote:
>
> the drive would see half the new data and half the old data.
I think that explaining it this way can easily lead to an incorrect inference
on the part of an arbitrary hypothetical neophyte that what is going on in the
drive i
On 2/27/23 12:55, r.stricklin via cctalk wrote:
>
>> On Feb 27, 2023, at 10:21 AM, Mike Katz via cctalk
>> wrote:
>>
>> the drive would see half the new data and half the old data.
>
> I think that explaining it this way can easily lead to an incorrect inference
> on the part of an arbitrary h
Actually it's not the controller, it is the fact that the head gap on
the 48 tpi drive is twice as wide as on the 96TPI drive.
So the actual head sees the magnetic fluxes from two different tracks,
This looks like noise to the data separator on the controller.
The way around this was to magn
For my students, I used analogies and visual aids.
1/48, 1/96 is a little hard for some to visualize.
"48 tracks per inch, is about half a millimeter spacing, with the actual
data being aabout a third of a millimeter wide.
96 tracks per inch is about a quarter of a millimeter spacing, with the
On 2/27/23 14:14, Fred Cisin via cctalk wrote:
> Then, I made the students describe how to make a 48tpi disk with a 96tpi
> drive.
One thing that folks need to bear in mind is that it's the change of
direction of magnetization that induces a signal in a drive head. So a
DC or AC erase on the "str
Then, I made the students describe how to make a 48tpi disk with a 96tpi
drive.
Whether to count their answers as acceptable or not was mostly just the
understanding of need for "bulk erase"/"virgin disk"
On Mon, 27 Feb 2023, Chuck Guzis via cctalk wrote:
One thing that folks need to bear i
It is also worth noting, that although not all "360K" diskettes are up to
the task, they will still be much closer than "HD"/"1.2M" diskettes!
"360K" diskettes are 300 Oersted
"Quad density" diskettes are also 300 Oersted. The only difference is
that "QD" diskettes are tested for 96tpi, where
On 2/27/23 15:50, Fred Cisin via cctalk wrote:
> Could you explain [in dumbed down form], the differences between "tunnel
> erase" and "straddle erase"? Is it solely that the erase head(s) are
> behind, VS alongside the R/W head?
How about ChatGPT's explanation? (Is this a first for CCTalk?):
W
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