Re: New 8" system works (was Lobo floppy drives)
- --- In firstname.lastname@example.org, Richard Cini <rich.cini@...> wrote:
>Why is that? I'm wondering why does a "SD" head care if it's a DD or SD disk?
> All --
> Today I was able to get my 8" Lobo drives working with my IMSAI. Whoo Hoo!
> What was giving me fits was that the drives weren't going "ready". Where I
> went wrong was that I was using DSDD disks for testing and not SSSD disks. I
> figured that the sides wouldn't matter but I was mistaken in thinking that
> the DD disks were backward-usable on the SD drives. Once I dug out SSSD Type
> 1 disks, everything worked. Yea!
I'm not doubting this, just wondering why.
I remember the days of DOS and how 360K disks (formatted on a 360K Drive) didn't work (for the most part) on 1.2M drives. The 1.2M drives were suppose to be able to be backward compatible with those DSDD 5.25 disks. Right?
- On Sat, 15 Dec 2012, joshbensadon wrote:
> --- In email@example.com, Mike Loewen <mloewen@...> wrote:Here's the service manual for the Tandom TM-848, with the schematics in
>> The double-sided drives have a 2S signal on pin 10 of the interface
>> connector to indicate single or double-sided media. The outputs of the
>> respective pulse-shaping ciruitry for each sensor is essentially ORed to
>> form a single Index pulse output.
> Cool, so I can imagine the two sensor signals going to an RS flip flop
> to provide the 2S signal and as you said to an OR gate for the index.
Knock yourself out. :-)
> Hmm, thinking about why, I guess the design was to create a hardwareThe 5.25" drives only had a single index hole aperture.
> error if a user placed a DS disk into a SS drive. As Rich found, the
> lack of index pulses caused a drive not ready. Correct me if I'm wrong,
> but in later 5.25" drives, they did not change the index sensor
> location. Then I suppose the errors created would be software
> I vaguely remember hearing a discussion about how computers switchedI couldn't say. Certainly Woz did a lot in software for his Apple II
> from hardware solutions to software solutions, then back to hardware.
> I just don't know the dates, could this 8" to 5.25" be part of that
disk controller design. Another odd thing about the 8" drivers vs the
5-1/4" drives was that the 8" drives had a write-enable notch, while the
5-1/4: drives had a write-protect notch. Very confusing.
Mike Loewen mloewen@...
Old Technology http://sturgeon.css.psu.edu/~mloewen/Oldtech/