Re: [midatlanticretro] Lobo floppy drives
- From: B Degnan <billdeg@...>
Reply-To: "firstname.lastname@example.org" <email@example.com>
Date: Friday, November 16, 2012 11:47 PM
To: "firstname.lastname@example.org" <email@example.com>
Subject: Re: [midatlanticretro] Lobo floppy drives
Interesting....the S800's in the Intel MDS 720 photoed on my web site also have significantly different jumpers drive 0 vs. drive 1. Maybe that's how it's done, or the boot drive has a lot of differences that the non boot drive. I wonder what this drive was used for.
-------- Original Message --------
> From: "Richard Cini" <rich.cini@...>
> Sent: Friday, November 16, 2012 11:19 PM
> To: "firstname.lastname@example.org" <email@example.com>
> Subject: Re: [midatlanticretro] Lobo floppy drives
> Bill --
> I finished examining and cleaning the interior of the drive enclosure this
> evening. I took note of the jumpers on both drives ? interestingly there
> were many differences between the jumper settings, other than what would be
> expected (i.e., the drive select and the termination).
> Here are the jumper settings:
> Drive0: installed ? DS1-T1-X-B-A-Z
> Drive1: installed ? T2-HL-800-DS2-T3-T4-T5-T6-T1-X-B-A-Z (this drive is at
> the end of the cable)
> Drive1 also had a drive_ready modification which resulted in pin22 being put
> on pin4 of the interface connector (jumper R cut; wire from R to pin 4).
> Given this configuration I'm not entirely sure what system this might have
> been used in since the drives are set so differently. So, I reset the
> jumpers per the CompuPro Disk 1 instructions and once I build a cable, I can
> try it on my IMSAI. Overall the drives look very clean and free from
> excessive dust.
> Rich Cini
> Collector of Classic Computers
> Build Master and lead engineer, Altair32 Emulator
- On Sat, 15 Dec 2012, joshbensadon wrote:
> --- In firstname.lastname@example.org, 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/