>From: "Tom Jennings" <tomj(a)wps.com>
>
>On Tue, 25 Jan 2005, Eric Smith wrote:
>
>> By the way, those floppy drives must be incredibly valuable, since
>> 8 1/4" drives are *very* rare.
>
>Actually, they will become very common; since the universe is
>expanding, they'll become 8 1/4", 8 1/2", etc. Don't forget all
>floppies were 5.25" once, and some on this list talk about smaller
>drives, but we know they are all crazy. Unfortunately bit density
>decreases with time due to bogon density increasing.
>
Hi
It is a good thing that everything is also expanding along
with it. Keeping the drive aligned would be a real pain.
Dwight
On Jan 25 2005, 9:11, Eric Smith wrote:
> There are no specific documents on it. It's in the MCS650x data
sheet.
> It's just a 6502 die in a smaller 28-pin DIP package with not all of
the
> pins bonded out. Specifically, A12 through A15, RDY, /NMI, SYNC, SO,
> three NC pins, and one Vss pin are not available.
>
> The pinout is:
>
> /RES 1 28 Ph2 out
> Vss 2 27 Ph0 in
> Ph1 out 3 26 R/W
> /IRQ 4 25 D0
> Vcc 5 24 D1
> A0 6 23 D2
> A1 7 22 D3
> A2 8 21 D4
> A3 9 20 D5
> A4 10 19 D6
> A5 11 18 D7
> A6 12 17 A11
> A7 13 16 A10
> A8 14 15 A9
That's a 6506 (above). 6507 is:
/RES 1 28 Ph2 out
Vss 2 27 Ph0 in
RDY 3 26 R/W
Vcc 4 25 D0
A0 5 24 D1
A1 6 23 D2
A2 7 22 D3
A3 8 21 D4
A4 9 20 D5
A5 10 19 D6
A6 11 18 D7
A7 12 17 A12
A8 13 16 A11
A9 14 15 A10
Note Vcc is one pin lower (in number). 6507 has one more address line,
no IRQ, and no Phi1, but it does have /RDY.
--
Pete Peter Turnbull
Network Manager
University of York
On Jan 25 2005, 11:40, Bill Sudbrink wrote:
> without really trying:
>
> Part amusing story, part warning.
[ ... ]
> So I open up the drive, straighten out the latch and then, since I
have it
> apart anyway, decide to clean the head. I get a Q-Tip and some
alcohol,
> lift the pressure pad arm and clean the head. (Anybody spot the
problem
> yet?)
Yes, because I did it once on a similar drive. I had to dismantle it
to straighten the spring steel strip, and then re-align the upper head,
IIRC (it was a double-sided drive). Quite a few drives are like that.
--
Pete Peter Turnbull
Network Manager
University of York
Anyone have any old technical white papers on the MOS 6507, I know its just a slight variant of the 6502, but I would like to look over the original technical specifications for the chip, pinouts, opcodes, instruction set, etc...
Thanks,
Curt
without really trying:
Part amusing story, part warning. I have my OSI C4P all buttoned up with
the switcher supply tucked inside and I decide to fix another thing that
has been bothering me for some time. OSI used MPI B51 floppy drives with
most (all?) of their 5 1/4 inch systems. The B51 has an ejector spring
that operates via a two step latch (mechanical latch, that is). The first
step locks the spring when a diskette is inserted (so you can close the
drive door), the second step releases the spring once the drive door is
closed so that the diskette will be ejected when the door is opened. The
latch alignment is finicky and this drive had the spring locked and stuck.
So I open up the drive, straighten out the latch and then, since I have it
apart anyway, decide to clean the head. I get a Q-Tip and some alcohol,
lift the pressure pad arm and clean the head. (Anybody spot the problem
yet?) I put everything back together and fire it up. Now the drive is
flaky as heck. Read fails about 50% of the time. What did I break? I
check to see if the track zero sensor moved. Nope, original paint spots
are in place and uncracked. Did I, in fact, gunk up the head when I was
cleaning it? I look with a strong light and magnifying glass. The head
is smooth and clean. Did I pull some wire loose? Not that I can find.
After fooling with it for a while, I notice that the click of the head
load does not sound the same as before I took it apart. I look at the
solenoid, everything seems OK. I troubleshoot this for several evenings.
Finally, I go back to the head load investigation. I defeat the head unload
rail with a wedge of paper (so that the head will be loaded whenever the
drive door is closed). No help. Then, finally, I use a dental mirror to
look at the head and pressure pad with a disk inserted. The pad is not
in contact with the diskette surface! What the!?!?!? It turns out that
the pressure pad arm is "hinged" not with a proper hinge but with a thin,
somewhat springy, metal strip. There is also a proper coiled spring on
top of the arm to provide more pressure but, when I lifted the pad arm,
I flexed the "hinge" enough that the coil spring couldn't push the pad
into contact with diskette surface. If you just look at it with the
door open, everything looks fine. The pad arm seems to be firmly resting
on the unload rail, ready to drop down onto the diskette when loaded. So,
I disassembled the arm, gently flexed the "hinge" back to straight,
reassembled and back in business. One of the oddest things I think I've
ever had to work out. Maybe this is getting me ready to tackle my ASR33.
Bill
Hi
Most of these were designed such that a single
output pullup resistor didn't use all of the
sink of an output transistor. This means that
two outputs tied together and would not draw too much
current.
DTL does the same thing and allows the wired AND.
As I recall, with RTL, you only needed to apply
power to one device if they were inverters
since there was no other active logic,
like flops.
Dwight
>From: "Steve Thatcher" <melamy(a)earthlink.net>
>
>I don't see how doing a wired-and is possible when RTL includes a pullup
resistor on each output. You would get to a point where an individual output
transistor would not be capable of sinking all the "low" current.
>
>You can get a basic idea of the logic families here...
>
>http://www.asic-world.com/digital/gates5.html
>
>best regards, Steve Thatcher
>
>
>-----Original Message-----
>From: "Dwight K. Elvey" <dwight.elvey(a)amd.com>
>Sent: Jan 7, 2005 12:22 PM
>To: cctalk(a)classiccmp.org
>Subject: RE: RTL Logic
>
>Oops!
> I forgot one thing. You can put several RTL outputs in
>parallel as a wired AND. You can't do that with the
>general CMOS or TTL. You'd need to look out for this.
> Does anyone have a source for DTL parts. There are
>a could I've been looking for.
>Dwight
>
>
>
Hello everybody,
once more I turn to the list in my quest for enlightenment...
At the university's computer collection where I work, an HP board with the
number in the subject turned up. It is a printed circuit board, about 7"
wide x 5" deep with a 2x50 trace edge connector. The only visible parts are
what looks like a few SMD capacitors; there are three black covers on the
board, two of them like 1"x2" in plastic (neat the connector edge), the last
one about 6"x3" and made from sheet metal (to the front edge). One of the
smaller ones has a Static Discharge warning label stuck on it. There are two
flat-but-heavy heat sinks bolted to the opposite side of the board, beneath
the two smaller covers.
One of the two black ejector handles on the front edge of the board says
"512k RAM". I haven't found any useful information by googleing, only a few
resellers.
We would like to know what machine this part is for; I suppose this will
make finding further information much easier.
Thanks in advance, yours sincerely
--
Arno Kletzander
Stud. Hilfskraft Informatik Sammlung Erlangen
www.iser.uni-erlangen.de
GMX im TV ... Die Gedanken sind frei ... Schon gesehen?
Jetzt Spot online ansehen: http://www.gmx.net/de/go/tv-spot
>From: "Jay West" <jwest(a)classiccmp.org>
>
---snip---
>
>I can't believe the 21MX M or E user guide isn't online, but I don't see it
>anywhere. You'll definitely need that book!
>
---snip---
Hi Jay
It seems like there is some manual on Al's site that describes
the 2100 instructions. As I recall, there was nothing specifically
for the 21MX, though.
I entered a few instruction on my machine and they seemed to work.
I also looked at some of the boot ROM's and the instructions
match. I'd load the boot ROMs and then just inspect the code.
I can't recall which manual it was without checking at home.
Dwight
>>(I'm not being a troll, really, I don't care what machine you use or your
>>reasons to or not to use it... I'm just poking fun at your claim that it
>>isn't powerful enough)
>
>[1] I thought the definition of a troll was someone who pokes fun at a
>person or people to get a 'rise' out of them, especially whilst making
>advocacy claims that clearly aren't true...
Ahh, but I wouldn't fit that definition, because I wasn't trying to get a
rise out of you. I didn't expect a response.
And how dare you say my claims aren't true. They have to be true... I
mean the fact that I have no support AT ALL to back up my statement that
there is no match to the Dual Proc G5 in the Windows world... well, you
think I need PROOF?!? Selam didn't need proof to claim Linux caused the
popular rise of the internet... proof be damned... I'm right because I
say I'm right!
:-)
(note the smiley... the internet way to point out sarcasm, less you
honestly think I'm being serious above)
>And no -- the Mac Mini isn't serious enough for video work, and there are
>some darned good PC platforms that are. 'Nuff said.
Well, yeah, I can't actually argue there. Although I am planning to buy a
Mac Mini for myself specifically to do A/V work... but that's because I'm
poor, and a Mac Mini is a cheap upgrade from my G3 iMac that will let me
bump up a notch in tools.
Hey, wait, if I'm planning to use it, are you saying I'm not doing
serious video work?!? I'll have you know, not ALL my videos are
comedies... there are a few dramatic scenes of a serious nature in
there... how dare you insult my work without seeing it (normally insults
wait until AFTER they see it and can justify the comment in any number of
ways... I ain't gonna win no inde fest)
:-)
(note the smiley again... although I am really hoping to get a Mac Mini
to do better video work then I can with my current iMac)
-chris
<http://www.mythtech.net>
I've got a Data I/O 29b with Unipak2 that is on the fritz. I thought it was
working, but it's not.
It frequently reads chips right, then 60 seconds later reads different
values with different checksums. It's sporadic. It never gives any failure
messages (other than bad verify ram to device). It just doesn't get the
right values sometimes.
I'm not up on the internals/repair of this unit, nor do I have time at the
moment and I need a working one ASAP.
Would anyone on the list know a shop that does repair of these units? Or
maybe be able to ship me a 29B and/or Unipak 2 so I can at least determine
which major component is ba and get over this hump?
Thanks for any thoughts/advice :|
Jay West
