Assuming people are still interested I'm working on other, lesser issues
now that the little thing works.
First thought: The interconnections between the CPU board and the IO
board/memory boards are weird. Basically it's a plate, insulator, board,
very odd spacer that provides
On Tue, Oct 13, 2020 at 2:29 PM Chris Zach via cctalk
wrote:
>
> I do have a card around here called an RXV21 from Plessy or something
> like that, maybe it could talk to an RX01 drive and format the disks?
>
Several of the 3rd party controllers could low level format disks.
For example:
RX01 format is a standard IBM format used by many systems, including
many CP/M ones, so it was possible to buy pre-formatted disks. Maybe
they came that way.
That may be it: The Elephant disk does say on the factory label: Single
sided, single density, IBM compatible, 128 bytes, 26 sectors.
On 13/10/2020 22:28, Chris Zach via cctalk wrote:
Then I guess the question rattling around my brain is "How did I get
this Elephant Memory systems disk formatted?"
RX01 format is a standard IBM format used by many systems, including
many CP/M ones, so it was possible to buy pre-formatted
> DEC controllers and DEC 8" drives cannot. Not for any platform.
>
> Back in the day, DEC floppy users purchased pre-formatted floppies.
> If you had an RX02, you could "INIT" an RX01 floppy to RX02 use -
> essentially just rewriting the data portion of the sector to
> double-density (256 bytes
On Mon, Oct 12, 2020 at 7:15 PM Chris Zach via cctalk
wrote:
> Well, the drive is working. Better...
Excellent!
> I've heard that the RX02 can format an RX01, but can it?
Nope.
There were 3rd party controllers that could format 8" media in DEC
machines (DSD for one).
DEC controllers and DEC
Well, the drive is working. Better.
Summary: The PDT11/150 needs to have resistors on the harness to the
floppy drives to limit the current for the sector LED. Without it the
LED will be "off" and you will get a quick 8 stepper motor clicks
without any click to load the heads. Looks like the
Curiouser and curiouser
On a lark I got a 47 ohm (actual reading 50.1 ohms) resistor from the
box, put it on the anode supply line of the sector pulse LED on the
drive that is in the PDT11 (not the one with the blown LED) and hooked
it up to the power supply.
With the resistor in I
On Mon, Oct 12, 2020 at 4:04 PM Chris Zach wrote:
>
> > In a 'real' RX01, each sensor LED (track 0 and index) has the cathode
> > grounded and the anode connected to +5V via a 68ohm series resistor.
> > If you measure the voltage across the pins with the LED disconnected
> > (or if the LED is
In a 'real' RX01, each sensor LED (track 0 and index) has the cathode
grounded and the anode connected to +5V via a 68ohm series resistor.
If you measure the voltage across the pins with the LED disconnected
(or if the LED is open-circuit) with any reasonable meter, it'll read
5V. The meter will
> One is for the solenoid that lowers the pad onto the disk to allow
> reads/writes.
>
> One is for the sensor to detect track 1 (LED and detector)
>
> One is for the sensor to detect sector pulse
>
> One is for the servo motor that moves the head in and out
>
> One is for the read/write head
>
>
When you swap the cables (and keep the drives in place), do you mean
that you swapped the data connection **and** the power supply cable(s)?
There are six wire bundles and connectors that hook an RX01 floppy drive
sub-module to the RX01 read/write controller board (or the PDT11
controller
See below.
Van: Chris Zach via cctalk<mailto:cctalk@classiccmp.org>
Verzonden: maandag 12 oktober 2020 03:14
Aan: Richard Pope<mailto:mechani...@charter.net>; On-Topic and Off-Topic
Posts<mailto:cctalk@classiccmp.org>
Onderwerp: Re: Firing up the pdt11
Well, by "location&
Maybe. The part number is partially missing, the drive itself has a part
number of 70-13077-02, DEC badged. That maps to a print set of
EK-13077-IP which doesn't seem to be anywhere online. Drat.
Looking at Wikipedia these seem to be in TO-18 metal cases. Maybe they
are Gallium Arsenide LEDs?
Could it have been a 5V LED with integral current limit?
That would explain the odd behaviour.
Kindest regards,
Doug Jackson
em: d...@doughq.com
ph: 0414 986878
Check out my awesome clocks at www.dougswordclocks.com
Follow my amateur radio adventures at vk1zdj.net
Ok, this is weirder: I put the "bad" floppy drive on the bench and
started to take a look at it. First I checked the LED (yes, it's an
LED). With a bench voltage of 1.5 volts and a 100ma draw it lit up
nicely in the IR (detected by phone camera, so nice they can see the
light) and the photo
Well, by "location" I mean there are plugs on the controller board for
PD0 (typically called the "top" drive) and PD1 (typically the "bottom"
drive). My test swapped the cables so the top drive was using the PD1:
logic on the board and the "bottom" was using the PD0 logic. In that
situation
Chris,
I would like to get a clarification on this. Does either drive work
fine in the PD0 position or does the drive that was not working in the
PD1 position not work in the PD0 position? You said that the spare drive
that you put in the PD1 position also does not work. I would try it in
18 matches
Mail list logo
