I would imagine this question has been asked hundreds
of times, but what to do about it? Im guessing soaking
it in bleachy water (50/50?). What say you?
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> Sounds similar to the Belkin Omniview (which I use---it was given to me by
>someone that no longer needed it). I too am using a PS/2->AT adaptor for a
>few of the units with no problem, but the PS/2->serial mouse adaptors won't
>work through it---I've tried. Well rather, what didn't work was:
>
> PS/2 mouse -> KVM -> PS/2 cable -> serial adaptor -> computer
>
> The unit I have also supports serial ports, so I suppose the following
>*may* work:
>
> PS/2 mouse -> serial adaptor -> KVM -> serial cable -> computer
>
> but I haven't tried that.
I have a 4 port one of those as well (in fact, the 8 port no name brand
one was replacing my 4 port Belkin).
My Belkin supported PS/2 for Mouse/Keyboard and AT Keyboard and Serial
Mouse. I could hook up any combination and it passed or adapted all the
signals. Very nice unit. Worked pretty well, although I had some problems
with it syncing to Windows NT 4 (I would have to wait about 30 seconds
after switching to an NT machine before I could use the mouse, if I tried
before waiting, it would just randomly bounce all over the screen
clicking... I got myself into a couple of bad situations that way as it
decided to click on the wrong thing).
I originally was looking on ebay for another of the 4 Port Belkin
OmniView units I have, but all the used ones were going for close to, or
even over the price of the 8 port no name one I got. And none of the
Belkin ones had cables or the rack mount frame, which meant the final
price would be even higher. So I gave the no name brand a try, and I've
been very happy with it. The other nice thing is the Belkin took up 2.5
rack spaces, which means if I got a 2nd one, I'd have lost a total of 5
spaces to run 8 items. The no name brand is a 1u device so I saved quite
a bit of rack space.
-chris
<http://www.mythtech.net>
Apologies if this is OT
I've been amassing bits and pieces to build my own little data centre at
home (all rack mount stuff - some of which is probably approaching
classic anyway).
All I'm missing at the moment are two racks (an integral part of a rack
mount system :-) but I think I've sourced a couple locally (they're to
expensive to ship from interstate) and a KVM switch (8 port minimum).
Everyone wants a truck load of $ for KVM switches and I figure for the
price it might be more fun to build one but I've been struggling to
locate a circuit diagram. I figure they're just a fancy switch of some
type.
Anyone have any pointers please?
TIA!!!
++++++++++
Kevin Parker
Web Services Consultant
WorkCover Corporation
p: 08 8233 2548
m: 0418 806 166
e: kparker at workcover.com
w: www.workcover.com
++++++++++
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I thought I had this mastered but apparently I don't, and it's driving
me nuts.
Background: The PCjr, PC and XT use floppy controllers that support
double density data rates. High density drives (1.2MB & 1.44MB)
obviously support faster data rates, but also support the slower data
rates for compatibility with double density media.
A nice upgrade for an old machine is to add a 3.5" floppy drive.
Genuine 720K double density drives are pretty hard to find now, but of
course 1.44MB drives are all over the place. The 1.44 MB drives have
nearly the same pinout as a classic 5.25 double density drive, and they
usually have a media sensor switch which forces them to use a slower
data rate when using double density media.
So I swapped the 5.25 double density drive from a PCjr and replaced it
with a 1.44MB drive. The Jr can't tell the difference electrically - it
wil just use 40 of the 80 tracks. Everything else will be the same.
It ran diagnosics and made all of the right noises, then failed. Hmm.
So I took the double density media I was using and cut a copy of DOS 3.3
onto it and tried again. Disk boot failure. Hmm.. bad media. Tried
again, different diskette. Hmm.. consistent.
To make a long story short:
- Original IBM DOS 3.3 diskette: boots and runs fine in any drive.
- DOS 3.3 copied onto a diskette by Windows or Linux using a 1.44MB
drive and booted in a Jr with a 1.44MB drive: boot failure, but disk is
readable. Just parts of track 0 are unreadable.
- DOS 3.3 copied onto a diskette by the PCjr using a 1.44MB drive.
(Booted first with the genuine DOS 3.3, tried to format /s.) Formatting
failed - bad media. (Media is good on other machines.)
So I found a genuine 720K drive, put it in the Jr, booted DOS and copied
DOS again. Then I put the 1.44MB drive back in and booted from the new
diskette. It worked!
Basically, it's behaving like the 1.44MB drives in both the bigger PCs
and on the Jr can't format the 720K media correctly. And I tried
several drives (Sony and Teac) and it failed consistently. A real 720
drive can create a diskette that the other drives can boot from.
(The bigger PCs with the 1.44MB drives *dont* have a problem with the
copied diskette.)
Just whipped out the multimeter. The 1.44MB drive definitely sees
double density media - pin 2 is being driven high for double density
media where normally it would be low. The controller ignores it either
way, has pin 2 was unused back then.
Does anybody have experience with doing something like this? I thought
that the 1.44MB drives had a media sensor that would slow down the
recording rate when using double density media. There should have been
no problem coping/formatting double density media. And yet, here I am ...
Mike
I spent a big part of yesterday sorting out the DEC cards that I've been
picking up the last couple of weeks. This morning I photographed SOME of
the PDP-8 cards. Take a look
<http://www.classiccmp.org/hp/My%20PDP-8%20Cards/> there's definitely some
odd stuff there! This is just a small part of the ones that I got. I'll add
more photos and (hopefully) descriptions later. If anyone wants to take a
stab at identifing some of the third party cards and/or writing a
description I'll be glad to post it.
Joe
Hi Fred,
>Check with Uncle Roger, if he's still around.
>I sold him two HC-20s (the Japanese model (different color, katakana
>on the keyboard, and different ROMs)), and gave him a tote of docs
>that included schematics. All the text is in Japanese, but a schematic
>is a schematic.
Um... who is "Uncle Roger"? Is he a participant in this list? How to
contact him?
Regards and thanks for responding.
Dave
--
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
http://www.parse.com/~ddunfield/museum/index.html
A friend of mine showed me some 8" disks labeled "Apple" written on the
label but did not have an Apple logo on them. Did Apple ever issue
software on 8" disks and/or support 8" drives?
This makes sense since he also has quite a bit of Lobo Drives stuff
including two Lobo HD/8" Floppy units and a dual Lobo 8" floppy unit.
One of the floppies had "CP/M" in the description, so it sounds like I
need to take care to keep stuff together.
And I will certainly keep my open for SVA and other Apple II controllers
... now that I know they exist :).
Thanks for the responses!
> > Did Apple ever [...] support 8" drives?
> (Typically they were used for interchange with CP/M systems, although
> I know of a few used to exchange RT-11 and UCSD stuff.)
>
> The brands I remember are Vista and Lobo. I think Lobo had patches
> for 8" drive access via Microsoft Softcard and CP/M.
>
> Tim.
Hi Tony,
>Now, I would start by checking that LCD supply voltage signal. It starts
>on the main board where IC 2C (4049) acts as an oscillator and driver to
>operate a voltage doubler, You should see about 7V (I think) on the +ve
>end of C1 or C6. This then goes up to the keyboard, to a 2 transistor
>voltage controller circuit there. Check for an adjustable voltage (set
>with the thumbwheel on the side of the machine) at the emitter of Q2 on
>the keyboard. This voltage, BTW, is fed back to the mainboard to power
>some of the ICs that connect to the LCD driver chips.
Thanks for the useful information.
I am seeing only about 3.5v on C1/C6 ... and it has about a 1v DC
square(ish) wave superimposed on it. I see the same voltage/waveform at
the transistors, and on the voltage input to the LCD. The thumbwheel
does not affect it a whole lot - it mostly clips the tops of the square
wave.
Unplugging the LCD module makes little difference, so it's not a loading
issue (at least not from the module).
I see lots of very healty looking 5v square waves coming out of IC2C,
however I am having a great deal of difficulty trying to trace the circuit
on the board. Can you give me a bit more of the circuit? Which pins
coming out of IC2C are driving the power supply, and what is the circuit
between these and C1?
Regards,
Dave
--
dave04a (at) Dave Dunfield
dunfield (dot) Firmware development services & tools: www.dunfield.com
com Collector of vintage computing equipment:
http://www.parse.com/~ddunfield/museum/index.html
> However, if I try to READ a file, and I've tried this with dd and
> Eric Smith's tapedump utility and whatnot, it always returns with
> 0 files read. It apparently sees the file marks as it will say its
> reading file 1, file 2, etc., but it never actually dumps anything.
>
> I've tried the multiple tapes at multiple densities and they are
> tapes I've read before on another system.
Any idea what block size was used to write the tapes? Any relevant
messages in the kernel log (i.e. output of "dmesg")? Which /dev/device
are you using to access the drive? What's the dd command you're using?
> WTF???
Sounds like _my_ life. :-)
De
