On Nov 19 2005, 9:58, Paul Koning wrote:
> >>>>> "Barry" == Barry Watzman <Watzman at neo.rr.com> writes:
>
> Barry> However, one question, this chart shows the high-order bit
> Barry> (parity bit) punched for every character, no exceptions. Was
> Barry> that a standard convention in sending ascii files to paper
> Barry> tape?
>
> You mean the high order bit was always on -- as opposed to being a
> parity bit? That's unusual. Parity is a bit more common, but I
don't
> think there was a single standard. Classic ASCII is a 7-bit code,
> leaving the 8th bit for people to mess with as they saw fit.
It's called "mark parity", though it's not really a parity indicator at
all, just a way of defining that that bit is always set. It's exactly
equivalent to having 7-bit data with an extra stop bit and not unusual
at all on PDP-8s, in fact it's the norm. All DEC-supplied ASR33s were
set for mark parity, as far as I know.
--
Pete Peter Turnbull
Network Manager
University of York
A Corvus _Unix_ box? What was the model designation for this beast? I
have a Corvus Concept 68k with shelves full of manuals and lots of
software. None of it seems to be Unix-y.
--
Do you have the service manual for the Corvus Omnidrive?
I've been trying to find that for the bitsavers archive for a
while now.
Corvus took the basic Concept hardware and added a SUN-style MMU
to the memory board and tried to sell it with Unisoft Unix as a
first try at a Unix computer. This machine didn't have a bitmapped
display.
There were several iterations of the design (Frank McConnell may
remember all of them). The two that probably sold the most were
to Valid Systems as the SCALDstation, and to Unisys.
On Nov 19 2005, 2:14, Tony Duell wrote:
> Are there any Econet enthusiasts here?
Yes :-)
> I've just bought most of an Acorn Econet fileserver (it's missing the
2
> floppy drioves and their cables, the mainboard and PSU look intact).
>
> The mainboard contains :
> 65C102 CPU
> 64K EPROM (2 off 27256). I've not tried to look at their contents yet
There are several versions of the firmware, each with its own little
idiosyncracies ;-) One EPROM is the MOS and the other is the
fileserver code, as you might expect.
> 64K DRAM
> WD2793 disk controller (not what I'd expect from Acorn)
> 6522 VIA
> Real time clcok chip and backup battery
> TTL glue
> An Econet module (looks like the one used in a Master or Arc, the
type
> with the hardware collision detection). Oddly theres a 26LS30 on the
> mainboard, does this thing source the Exonet clock too?
Yes, it does, and it's a decent asymmetric clock. It's supposed to
switch itself off (or actually, I suspect, not switch on at boot time)
if it detects another clock already on the wire.
> The PSU looks to be a normal switch-mode unit giving +5V and +12V
>
> On the back are the 5 pin DIN econet socket, a 26 pin header
identified
> as 'Printer' (presumably wired as a BBC micro printer port)
Yes, just as normal.
> and a 34 pin
> header. I am told this is to add a hard disk, and it looks similar to
a
> Beeb's 1MHz bus. I assume it takes the normal SASI host adapter and
ST506
> bridgboard (I have spares of those somewhere...)
Yes.
> On the front are 2 LEDs (power and mode) and what looks like a
> reflectiove optoswitch (why?)
The optoswitch detects whether the front panel is in the open or closed
state. When closed, the box starts up as a server. When open, it runs
in maintenance mode. The plastic "hinges" were rather fragile and
frequently broke, leading sometimes to the loss of the cover.
> Can anyone tell me anything more about it, how to use it, what the
> intenral links do, etc?
I should have the manual somewhere. You shouldn't need to change any
links.
--
Pete Peter Turnbull
Network Manager
University of York
Today I was hooking up my homebrewed driver board to the M-series
connector on the back of my Tally 420PR tape punch (interfaces to
my 8/A and . Fortunately, before I inserted the eight data pins
into the connector body it occurred to me that Tally and DEC might
not interpret the holes in the same order. And indeed they don't!
The paper tape has five holes on one side of the sprocket hole and
three on the other. Typical DEC terminology is Bit 1 = MSB and Bit
8 = LSB. Is that in fact how DEC labeled it?
Is the MSB on the outside of the 5-hole side or the 3-hole side?
Which hole on the tape is which?
Even more interestingly, Tally labels their punch pins as follows:
(* is the sprocket hole)
8 7 6 1 2 * 3 4 5
and I confirmed this by actual test. So much for consistency
<sigh>
-Charles
Most of the PCI prototyping boards that I've seen are either outrageously
expensive or absolutely bare (i.e. no interface logic at all)--and still
not that inexpensive.
Does anyone know of a reasonable (<$100) PCI prototyping kit with a
reasonable amount of interface logic built on?
Cheers,
Chuck
>Date: Thu, 17 Nov 2005 23:33:45 +0000 (GMT)
>From: ard at p850ug1.demon.co.uk (Tony Duell)
>Some manufactuerers did not copy-protect their PALs. For example, all the
>PALs in the VAX 11/730 CPU are readable (for all they're the key to the
>design). All PALs in every PERQ I've seen (including the AGW3300) are
>readable. All PALs in the Torch XXX -- apart from those on the (3rd
>party?) 68020 kludgeboard -- are readable. But then again, most PALs on
>clone ISA boards are protected.
>
>If the original chip is a HAL, you are out of luck. HAL == Hard Array
>Logic, it's a mask-programmed equivalent to a PAL. I've never found one
>that can be read out, I suspect the circuitry simply isn't there.
Oops. Forgot to mention in my previous message. I saw a programmer
the other day that said it supported user defined test inputs to
PLDs. There wasn't any detail, but it sounded like you could use
the thing to set up a set of input data and get the results that come
out of a PLD. This could be much faster than sticking the target
chip on a breadboard and flipping switches and reading LEDs to
compare I/O.
Let's see, (checks bookmarks) it was the Dataman 48Pro.
Unfortunately, it retails for about $1000. Here's a quote from the
blurb: " Dataman 48Pro isn't only a programmer, but also a tester of
TTL/CMOS logic ICs and memories. Furthermore, it allows the
generation of user-definable test pattern sequences for PLD devices."
I have a Needham EMP-30 which will program the smaller PALs but I
don't think it has any provision for nifty testing of the I/O of the
things.
Jeff Walther
>Date: Mon, 14 Nov 2005 23:48:14 -0800
>From: "Chuck Guzis" <cclist at sydex.com>
>On 11/14/2005 at 11:24 PM Jeff Walther wrote:
>
>>For big surface mount chips I like to use Chip Quik desoldering
>>alloy, which will lower the melting point of the solder on the board.
>>If I preapply Chip Quik, I can usually use the 600F setting for a
>>minute or two to loosen a chip. I've successfully done this on chips
>>as large as 208 pin QFPs.
>
>Jeff, unless the thermostat on your heat gun is faulty, you should be able
>to go much lower than 600F, shouldn't you? 60/40 solder flows at about
>370F.
You would think so, wouldn't you? As I recall, I tried lower
temperatures first and it just took too long for the solder to
loosen. My back of a beer soaked envelope explanation would be that
the heat is conducting away at some rate and so one needs a higher
temperature source than the target temperature. But beats me. The
600F setting is the one that gets the chips loose in about 2 minutes.
The heat gun could be poorly calibrated. It was inexpensive but gets
the job done.
Interestingly, if I'm doing a bunch of boards, e.g. pulling the flash
off of cheap ATA-66 cards, after the first card the following ones go
faster. Either the heat gun takes a while to reach its set
temperature, or my work area gets hot and helps the boards along or
something. I use a 1/16" sheet of sheet metal as a work surface. I
figure it's anti-static protection and fairly impervious to
mechanical, chemical and thermal insult.
>It seems to me that I've also seen special desoldering rigs that use hot
>air and a special nozzle to better focus the airstream.
I've heard of those, but they seem to cost multiple hundreds of
dollars. I like the < $40 heat gun + modeling clay solution.
That's a little bit of hyperbole as I also have dental picks and the
Chip Quik set for the big chips and a nice bottle of resin. With
those and a 15W and a 40W soldering pencil I manage.
>Thanks for the tip on Chip Quik; from the MSDS, it appears to be a
>Tin-Indium alloy.
I thought there was bismuth involved but the memory is moldy. It
melts/mixes in with the existing solder and lowers the melting point.
That's the point behind the stuff. It's fairly expensive, but very
little of it is needed per desoldered chip. And four beads of the
stuff makes the big QFPs come off soooo much easier.
Jeff Walther
>Date: Thu, 17 Nov 2005 23:33:45 +0000 (GMT)
>From: ard at p850ug1.demon.co.uk (Tony Duell)
>Some manufactuerers did not copy-protect their PALs. For example, all the
>PALs in the VAX 11/730 CPU are readable (for all they're the key to the
>design). All PALs in every PERQ I've seen (including the AGW3300) are
>readable. All PALs in the Torch XXX -- apart from those on the (3rd
>party?) 68020 kludgeboard -- are readable. But then again, most PALs on
>clone ISA boards are protected.
>
>If the original chip is a HAL, you are out of luck. HAL == Hard Array
>Logic, it's a mask-programmed equivalent to a PAL. I've never found one
>that can be read out, I suspect the circuitry simply isn't there.
There are a couple of articles in the archives about reverse
engineering the behaviour of PALs. One article started out very
promisingly (to my inexperienced eye) and the author stated that
parts 2 & 3 were to follow, but they never did. Oh well.
I would like to clone the external floppy drive and SCSI adapter for
the Outbound Model 125. I've acquired most of the required parts
for each. However, they each have a GAL 16V8 (just one per product)
installed. The terror at trying to figure the contents of that GAL
has been stalling me for months (well that, plus all the other stuff
around here, like getting the autumn garden planted).
How heat sensitive are PALs and GALs? Am I likely to deprogram the
thing when I desolder it from the board?
Jeff Walther
I just dug my Osborne 1 out of the attic after probably 10-15 years.
Blue case, double density motherboard.
Anyone have thoughts about osborne-specific things I should do before
just powering it up? It was in working order when stored, and has
been dry.
De
