28 Dec
2003
28 Dec
'03
8:31 a.m.
Just got back from Radio Shack. I bought a fast blowing 250v 2 amp fuse
and installed on in the laserdisc player. Unfortunetly, it blows just
as fast as the .75amp fuse. So.... that means I have a dead short
somewhere, right? How do I go about checking that?
Chad Fernandez
Michigan, USA
28 Dec
28 Dec
8:57 a.m.
New subject: new info on fuse
If you have a multimeter unplug your unit, install a good fuse or jumper in
the fuse holder, and check the resistance of power plug to the ground pin or
to the metal chasis on the player. Any continuity means you have something
shorting to ground. If you really need this unit running take it to a vcr
repair facility (if they still exists) and get an estimate for repair.
----- Original Message -----
From: "Chad Fernandez" <fernande(a)internet1.net>
To: <cctalk(a)classiccmp.org>
Sent: Sunday, December 28, 2003 5:31 PM
Subject: OT: new info on fuse
Just got back from Radio Shack. I bought a fast
blowing 250v 2 amp fuse
and installed on in the laserdisc player. Unfortunetly, it blows just
as fast as the .75amp fuse. So.... that means I have a dead short
somewhere, right? How do I go about checking that?
Chad Fernandez
Michigan, USA
12:24 p.m.
Just got back from Radio Shack. I bought a fast blowing 250v 2 amp fuse
and installed on in the laserdisc player. Unfortunetly, it blows just
as fast as the .75amp fuse. So.... that means I have a dead short
somewhere, right? How do I go about checking that?
Can you tell us a little about the PSU design? Is it a 'linear' PSU, with
an iron-cored mains-frequecy transformer? Or a switcher, with HV
capacitors (look for a couple rated at 200V each) and a chopper transistor?
If the former, can you disconnect the secondary windings of the
transformer from the PCB? If you can, then try a new fuse with the
windings disconnected. If that blows, then you have shorted turns in the
transformer, or a short in some component on the mains input side (RF
filter capacitor?).
If it's a switcher, then you have fun (for suitable values of 'fun'. You
need to check forwards from the mains input and at least find the mains
rectifier diodes and the chopper transistor. Check these for shorts. If
the transistor is OK, and one or more of the diodes is shorted, then
replace the diodes (use something rated at _at least_ 400V 2A) and try
again. If the chopper is shorted, well, you've probably got other
problems too, and _I_ wouldn't want to do much more without a schematic...
-tony
3:01 p.m.
Tony,
I pulled the power supply from the laserdisc player. I couldn't see it
adiquately in the machine.
Tony Duell wrote:
Can you tell us a little about the PSU design? Is it a
'linear' PSU, with
an iron-cored mains-frequecy transformer? Or a switcher, with HV
capacitors (look for a couple rated at 200V each) and a chopper transistor?
I find one cylindrical cap that is 200v and 220uf and one 250v .1uf cap
that looks like a chicklet (kind of chewing gum). I don't have any idea
how to identify a chopper transistor..... could that possibly be labeled
"Q1" and have a heat sink on it? I also see a couple transformers and a
bunch of resistors an IC and assume most of the D#'s are diodes. There
are quire a few "Q#" labeled items too.
This power supply does smell a little like something let the magic smoke
out.
If the former, can you disconnect the secondary windings of the
transformer from the PCB? If you can, then try a new fuse with the
windings disconnected. If that blows, then you have shorted turns in the
transformer, or a short in some component on the mains input side (RF
filter capacitor?).
If it's a switcher, then you have fun (for suitable values of 'fun'. You
need to check forwards from the mains input and at least find the mains
rectifier diodes and the chopper transistor. Check these for shorts. If
the transistor is OK, and one or more of the diodes is shorted, then
replace the diodes (use something rated at _at least_ 400V 2A) and try
again. If the chopper is shorted, well, you've probably got other
problems too, and _I_ wouldn't want to do much more without a schematic...
How would I check the rectifier diodes and the chopper transistor for
shorts? Check for continuity with ground on each pin?
Chad Fernandez
Michigan, USA
29 Dec
29 Dec
9:21 a.m.
Can you tell
us a little about the PSU design? Is it a 'linear' PSU, with
an iron-cored mains-frequecy transformer? Or a switcher, with HV
capacitors (look for a couple rated at 200V each) and a chopper transistor?
I find one cylindrical cap that is 200v and 220uf and one 250v .1uf cap that looks like a chicklet (kind of chewing gum). I
don't have any idea
Or a tkind of keyboard :-)
how to identify a chopper transistor..... could that
possibly be labeled
"Q1" and have a heat sink on it? I also see a couple transformers and a
Yes. Q = transistor on most PCBs. The chopper with be on the mains side
of the PSU (and thus will probably have a fairly low number, like Q1) and
will almost certainly be on a heatsink.
bunch of resistors an IC and assume most of the
D#'s are diodes. There
Are there any recognisable markings on the IC?
are quire a few "Q#" labeled items too.
This power supply does smell a little like something let the magic smoke
out.
Ah...
How would I check the rectifier diodes and the chopper
transistor for
shorts? Check for continuity with ground on each pin?
Does your meter have a 'diode test' range? Most do.
If the rectifier is made of individual diodes, then desolder at least one
end of each one, and test them with the diode test range of the meter.
They should conduct (forward voltage -- what the meter displays -- about
0.7V) in one direction, and be open-circuit (meter shows overrange in
some manner) in the other.
If the rectifier is a 4-terminal bridge 'block' then the 4 leands will be
+ve, -ve, and 2 AC. You'll have to work out which is which.
Check (with the rectifier out-of-circuit)
AC to AC : open both ways
Each AC to +ve (2 separate tests) : acts as a diode
Each AC to -ve : acts as a diode
+ve to -ve : looks like a diode with twice the forward drop (about 1.4V)
For the chopper transistor, again take it out of circuit. You need to
identify the connections -- look up the type number in a databook (or get
me to see if I can find it :-)). If it's a flat plastic package with a
metal tab and 3 pins out of one end, then, with the tab downwards and the
leads towards you, the order is likely to be b,c,e from the left. The
collector (c) is also likely to be connected to the tab.
Anyway, once you've done that, check (using the diode test range) :
c to e : open circuit both ways
b to c : acts as a diode
b to e : acts as a diode
-tony
31 Mar
31 Mar
1:27 p.m.
New subject: Help me! Before I take the plunge
Okay, so out of curiosity I found the listing for the Decmate on eBay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=1247&item=51…
Now, this is a pretty cool looking critter.
Please bear in mind that I'm essentially an 8-bit micro guy, and I have
no experience with larger machines except for a VaxStation(not counting
PC crap, of course). I've always considered getting a larger machine
but have never had the space, or the wiring, or the tact required to
convince my better half that having such a machine in the house would be
a good thing.
However, the Decmate has a number of appealing qualities:
Small size -- will fit in my HideOut (computer room)
"Somewhat" PDP-8 compatible -- a whole new world for me
Affordable -- even with shipping it's within my budget
Attractive appearance -- looks like a computer my wife can relate to
instead of some gargantuan refugee from a '50s sci-fi movie
On the other hand, I have some questions (I did a little Googling and
have more to do, but I know there are folks here who can answer my
questions quickly and accurately):
Is it a fair value at $200 plus (probably) another $200 for shipping?
Is technical documentation available?
What OSes will run on it? (OS/8 ?) Are they available for download?
What software, languages, assemblers, etc. are available?
How compatible is it with the PDP-8 -- ie, will it run PDP-8 software?
Does it have a free serial port so I can download software onto a PC and
then serial-transfer it to the Decmate?
How expandable is it? What sort of bus does it have?
What are the Decmate's disadvantages?
Is there a better machine I should hold out for which is small and in
the same price range?
If it has problems, are there people on this list who will help me
troubleshoot the thing (I have a 'scope, logic probe, meter, soldering
tools, etc.)?
Any and all feedback is really appreciated.
Glen
0/0
2:26 p.m.
New subject: Help me! Before I take the plunge
Small size -- will fit in my HideOut (computer room)
"Somewhat" PDP-8 compatible -- a whole new world for me
Affordable -- even with shipping it's within my budget
Attractive appearance -- looks like a computer my wife can relate to
instead of some gargantuan refugee from a '50s sci-fi movie
Well, sort of halfway between :-).
There are also smaller, cheaper DECmates, too. My experience is mostly with
the DECmate III. (Hopefully someone will correct me if something I say
doesn't apply to the DECmate I.)
On the other hand, I have some questions (I did a
little Googling and
have more to do, but I know there are folks here who can answer my
questions quickly and accurately):
Is it a fair value at $200 plus (probably) another $200 for shipping?
That's a subjective call. However, if I didn't already have two (well, one
and a half, really), I'd be interested.
Is technical documentation available?
Yes. Too lazy to look up the URLs, but they aren't hard to find. I think
the hardware info (at least) is available at bitsavers.
What OSes will run on it? (OS/8 ?) Are they available
for download?
There's a special version of OS/8 for DECmates, I think one of the other
OSes also runs on DECmates, but can't remember offhand which it was. It
usually comes with a word processing system.
Yes. I downloaded a bunch of floppy images a while back. The trick will
probably be getting something to write the funky 8" floppies.
What software, languages, assemblers, etc. are
available?
How compatible is it with the PDP-8 -- i.e., will it
run PDP-8 software?
There is a silly incompatibility in the keyboard interface that can cause
characters to be lost with some programs, and I found a bug in the console
output firmware on a DECmate III that required a 1-word patch to Focal '69
to work around.
There is no EAE (extended arithmetic instructions) in a DECmate I, and that
software will hang if you try to use it. Also, a lot of software used to
use the switch registers, and used to halt to let you look at the lights or
change the switches. None of that will work, since the DECmate I cannot
continue from a halt. (Since there aren't any switches or lights, you
likely wouldn't try to run that stuff anyway.)
Most of the programming languages and sort of mainstream stuff will probably
run (possibly with minor tweaks). All the process control and funky
hardware stuff is (naturally) hopeless.
Does it have a free serial port so I can download
software onto a PC and
then serial-transfer it to the DECmate?
It should, but you might need a DP278 board.
I think the 12 bit Kermit stuff is used for this kind of file transfer.
How expandable is it? What sort of bus does it have?
I understand there was an RL02 controller, and some COM (DP278) boards, for
the DECmate I.
What are the DECmate's disadvantages?
Various minor software incompatibilities, mostly with the console interface.
Most of them have been well documented.
Is there a better machine I should hold out for which
is small and in
the same price range?
The DECmate II is about the size of a large old fashioned PC-AT. The
DECmate III is smaller (makes a fine stand for the monitor), but has no
second drive bay, so you get just the dual floppy drive it comes with. Both
of these use 5.25" floppies in RX50 format instead of 8" floppies in RX01
format like the DECmate I. Both come with a communications port.
IIRC, both these machines take coprocessor options which can run some flavor
of CP/M. The DECmate II takes an option for a MFM hard disk. These option
cards are pretty hard to find, if they don't come with the DECmate when you
buy it.
If it has problems, are there people on this list who
will help me
troubleshoot the thing (I have a 'scope, logic probe, meter, soldering
tools, etc.)?
Should be. I've used my DECmate III a bit, debugged around some
compatibility issues, etc. I haven't got 'round to trying out my DECmate I,
though.
Vince
11:53 p.m.
New subject: Help me! Before I take the plunge
On Mar 31, 2005 5:26 PM, vrs <vrs at msn.com> wrote:
The DECmate II is about the size of a large old
fashioned PC-AT. The
DECmate III is smaller (makes a fine stand for the monitor), but has no
second drive bay, so you get just the dual floppy drive it comes with. Both
of these use 5.25" floppies in RX50 format instead of 8" floppies in RX01
format like the DECmate I. Both come with a communications port.
There is a somewhat rare option board for the DECmate II that provides
an RX02 interface, but I know little about it; I've never seen one.
So that board aside, the DECmate I (and VT78) use 8" floppies, and the
DECmate II and DECmate III use 5.25" RX50 floppies.
-ethan
2:42 p.m.
New subject: Help me! Before I take the plunge
Okay, so out of curiosity I found the listing for the
Decmate on eBay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=1247&item=51…
Now, this is a pretty cool looking critter.
Damn right, if I was that side of the pond I'd be all over it. I would say
just buy it and bask in the knowledge that you've saved a pretty good bit
of DEC kit. Even my Missus said that it looked like an interesting machine
and she's seen my MINC out in the garage :)
--
adrian/witchy
Binary Dinosaurs creator/curator
www.binarydinosaurs.co.uk - the UKs biggest home computer collection?
8:17 p.m.
New subject: Help me! Before I take the plunge
On Apr 1, 2005 5:27 AM, Glen Goodwin <acme at gbronline.com> wrote:
Okay, so out of curiosity I found the listing for the
Decmate on eBay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=1247&item=51…
Now, this is a pretty cool looking critter.
Yeah. It's a beautiful specimen of early 80s DEC engineering /
Is it a fair value at $200 plus (probably) another $200 for shipping?
Is technical documentation available?
Well that depends on who you're talking too.
These are I think the only 3 docs available online for the DECmate
(VT278) system.
http://www.bitsavers.org/pdf/dec/pdp8/cmos8/MP00900_VT278_may81.pdf
http://www.bitsavers.org/pdf/dec/pdp8/cmos8/MP01237_278sys_jun81.pdf
http://pdp-8.org/scans/an/ek/ek-vt278-hr-001.pdf
What OSes will run on it? (OS/8 ?) Are they available
for download?
It runs OS278, different enough that AFAIK most OS8 software won't
run. The incompatibilities is mainly due to the non-standard
non-OMNIBUS hardware boards that it uses.
The below is a part of Doug Jone's superb FAQ on PDP8 and it's variants.
<incompatibilities>
A new feature was introduced in the 6120 microprocessor:
The Group I OPR combination RAL RAR was defined as R3L, or rotate
accumulator 3 places left, so that byte swap (BSW) is equivalent
to R3L;R3L. RTR RTL remained a no-op, as in the 6100.
Also, the EAE operations not implemented in the basic CPU cause
the CPU to hang awaiting completion of the operation by a
coprocessor. Unfortunately, no EAE coprocessor was ever offered.
The printer port offered software baud-rate selection compatable
with the VT78 baud-rate selection scheme. The dual-port data
communications option was flexible but completely incompatable
with all previous PDP-8 serial ports.
The console and printer ports are not fully compatable with the
earlier PDP-8 serial ports. Specifically, on earlier serial
interfaces, it was possible to test flags without resetting them,
but on the DECmate machines, testing the keyboard input flag
always resets the flag as a side effect. In addition, on the
console port, every successful test of the flag must be followed
by reading a character or the flag will never be set again.
It was not possible to continue from a halt without restarting
the machine.
The large amount of device emulation performed by the CPU in
supporting screen updates severely limits the ability of the
system to run in real time.
</incompatibilities>
Don't know whether OS278 is available or not or for which media. Have
to look for it by yourself.
What software, languages, assemblers, etc. are
available?
How compatible is it with the PDP-8 -- ie, will it run PDP-8 software?
Does it have a free serial port so I can download software onto a PC and
then serial-transfer it to the Decmate?
Depends on whether it has the optional DP278 board which provides 2
serial ports.
How expandable is it? What sort of bus does it have?
Takes in 3 slots at the back (these are not regular OMNIBUS slots,
it's proprietary to the DECmate).
Slot 1: CPU board + floppy + printer + keyboard
Slot 2: Optional (typically DP278 serial controller)
Slot 3: Optional (typically RL278 disk controller)
The DP278 and RL278 are quite rare nowadays. If your unit doesn't
already have them, you'd be hard pressed (at least your wallet will)
to find them.
Another one of DECmate's advantage is that:
You get a VT100 free! :-)
[Caveat: This is only if you have a DP278 board. Otherwise you'd have
no where to connect it to the host...]
What are the Decmate's disadvantages?
Is there a better machine I should hold out for which is small and in
the same price range?
I don't know, but to me:
- DECmate 1...wow! Such character, and it's soooo 70s :-)
- DECmate 2.. eh? Looks like a PC AT?
- DECmate 3.. Is that a computer or an external disk unit?
If it has problems, are there people on this list who
will help me
troubleshoot the thing (I have a 'scope, logic probe, meter, soldering
tools, etc.)?
The prints/schematics are available.
/wai-sun
10:49 p.m.
New subject: Help me! Before I take the plunge
On Mar 31, 2005 4:27 PM, Glen Goodwin <acme at gbronline.com> wrote:
Okay, so out of curiosity I found the listing for the
Decmate on eBay:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=1247&item=51…
Now, this is a pretty cool looking critter.
Very 1980s...
Please bear in mind that I'm essentially an 8-bit
micro guy...
However, the Decmate has a number of appealing qualities:
Small size -- will fit in my HideOut (computer room)
"Somewhat" PDP-8 compatible -- a whole new world for me
Affordable -- even with shipping it's within my budget
Attractive appearance -- looks like a computer my wife can relate to
instead of some gargantuan refugee from a '50s sci-fi movie
It is smaller and cheaper than, say, a PDP-8/e...
On the other hand, I have some questions (I did a
little Googling and
have more to do, but I know there are folks here who can answer my
questions quickly and accurately):
Is it a fair value at $200 plus (probably) another $200 for shipping?
Others have chimed in, but let me put it this way... _I_ didn't
consider a bid for it.
OTOH, if one has a number of DEC machines, one can one or both of the
RX02s in the pedestatl with, say, a PDP-11. They are indepenent, BTW,
so one could hook one RX02 to the DECmate, and the other to a MINC-11
(same DB-25 external cable pinout).
Is technical documentation available?
Yes, on bitsavers. I was just reviewing the docs for it the other
day, and the schematics look complete.
What OSes will run on it? (OS/8 ?) Are they available
for download?
OS/278 has the necessary patches to deal with the differences in the
console IOT behavior that was well described in another post. Dunno
about download, but you'd have a problem with the downloaded file,
since the RX02 format can _not_ be written by a PC FDC (it's a hybrid
format that only the RX02 drive (and DEC-compatible 3rd-party
drives/controllers) can write.
What software, languages, assemblers, etc. are
available?
Once one has OS/278 up, the list is the same as for OS/8. Primarily,
folks wrote in FORTRAN or 12-bit MACRO, but there are a few other
languages available.
How compatible is it with the PDP-8 -- ie, will it run
PDP-8 software?
Yes, except for the aforementioned console incompatibilities. It's
not hard to tweak stuff to work with the DECmate, but stuff that does
its own console IOTs _does_ need to be slightly tweaked. Much easier
with the MACRO source than without.
Does it have a free serial port so I can download
software onto a PC and
then serial-transfer it to the Decmate?
I don't remember. If one has the communications board (DP278?), one
has the spare port for sure. The only problem then is a
chicken-and-the-egg problem... how to get a program into memory
without already having a program that understands that protocol. The
quickest answer (but not necessarily the easiest answer) is to get a
bootable RX02 disk with Kermit on it.
How expandable is it? What sort of bus does it have?
It is in-cabinet expandable only... the available options are more
serial ports (DP-278), and an external hard disk (RL278?) I have
never personally held either option.
The bus is a proprietary one, that happens to fit on two slots
mechanically identical to, say, an Qbus. The pinout is described in
the pdfs on bitsavers.
What are the Decmate's disadvantages?
Not console IOT compatible
EAE not possible to attach.
Is there a better machine I should hold out for which
is small and in
the same price range?
DECmate IIs and DECmate IIIs are cheaper... I don't consider them if
they are loaded with standard equipment and priced above about $40.
It's easy to add a hard disk (ST-225, for example) to a DECmate II,
making it attractive. The DM II and DM III also use 5.25" 'RX50'
diskettes which *can* be read/written from a Linux/Windows/etc machne.
There's also the possibility for going with an SBC6120
(http://www.sparetimegizmos.com/), but the SBC6120 is *not* cheaper
(but it is smaller and more compatible) than this DECmate I. With
front panel and I/O board, I have several hundred dollars in my
SBC-6120, but at the moment, they are a lot rarer than even the
PDP-8/S.
-ethan
11:07 p.m.
New subject: Help me! Before I take the plunge
On Thursday 31 March 2005 22:49, Ethan Dicks wrote:
--snip--
OS/278 has the necessary patches to deal with the
differences in the
console IOT behavior that was well described in another post. Dunno
about download, but you'd have a problem with the downloaded file,
since the RX02 format can _not_ be written by a PC FDC (it's a hybrid
format that only the RX02 drive (and DEC-compatible 3rd-party
drives/controllers) can write.
I have a couple of DECMATE IIs and I use PUTR (running under DOS) to format
RX50 diskettes and transfer files to the diskettes. I've also used TELEDISK
to copy entire diskettes that I have downloaded and have created virtually
all of the system programs on RX50 diskettes (OS/278, Word Processing, DIBOL,
etc.) that run on a DECMATE II.
I haven't worked with a DECMATE I since the original one I used at work many
years ago - but as I recollect it is not anywhere near as flexible as a
DECMATE II (which has HDD capability - which I've implimented in both my
DECMATE IIs).
The DECMATE I could still be a fun system to own - and if you can find DECMATE
I system images, both PUTR and TELEDISK will make it easy for you to create
entire copies of diskettes (TELEDISK), format (PUTR) and transfer files
(PUTR).
Cheers,
Lyle
--
Lyle Bickley
Bickley Consulting West Inc.
http://bickleywest.com
"Black holes are where God is dividing by zero"
11:49 p.m.
New subject: Help me! Before I take the plunge
On Apr 1, 2005 2:07 AM, Lyle Bickley <lbickley at bickleywest.com> wrote:
The DECMATE I could still be a fun system to own - and
if you can find DECMATE
I system images, both PUTR and TELEDISK will make it easy for you to create
entire copies of diskettes (TELEDISK), format (PUTR) and transfer files
(PUTR).
TELEDISK and PUTR will not solve the problem that a PC can *not* write
RX02-format 8" disks. They are a strange mixed-density beast that can
only be written by RX02-compatible drives. RX01 disks _can_ be
written by a PC with the right FDC chip, but since the DECmate I
shipped with RX02s, not RX01s, its disks are RX02-format.
Possibly one could build RX01 diskette images with the right contents
(with twice as many diskettes) and migrate things over that way, or
emulate the RX02 itself with a PC, but one can *not* just slurp and
burn RX02s directly from a PC.
-ethan
1 Apr
1 Apr
6:25 a.m.
New subject: Help me! Before I take the plunge
Ethan Dicks wrote:
Possibly one could build RX01 diskette images with the
right contents
(with twice as many diskettes) and migrate things over that way, or
emulate the RX02 itself with a PC, but one can *not* just slurp and
burn RX02s directly from a PC.
Has anybody built the RX emulator described at
http://www.chd.dyndns.org/rx02/
The page says that RX02 support isn't finished, but that the RX01
handler is working.
(Ethan, your gmail address is set as reply-to)
Doc
7:18 a.m.
New subject: Help me! Before I take the plunge
On Apr 1, 2005 9:25 AM, Doc Shipley <doc at mdrconsult.com> wrote:
Has anybody built the RX emulator described at
http://www.chd.dyndns.org/rx02/
The page says that RX02 support isn't finished, but that the RX01
handler is working.
I have not built it, but I did have that project in mind when I
suggested that one could emulate an RX02 attached to a DECmate I. One
advantage of the DECmate I CPU is that the controller for the second
drive pair is not an option; it's always present. All one needs is a
straight-through DC37-to-DB25 cable for a single drive, or a
DC37-to-dual-DB25 Wye cable for both RX02s.
I do not have the cable myself (my DECmate I has only one set of
drives in the pedestal), but from reviewing the VT278 schematics, it
would be as easy to fabricate as a modem cable. If one owned a
DECmate with a single set of drives, one could make the dual cable,
attach the 0/1 cable to the emulator, the 2/3 cable to the real
drives, and very easily take OS/278 images on a PC, boot to a prompt
on an emulated drive zero, then copy images from an emulated drive 1
to a real drive 2 or 3. Once one is up and running on real RX02
media, one can swap the DB25 cables and have drives 2/3 emulated.
Since I do not have OS/278, I might just do that some time.
I just wish there were an easy way to attach a real RX02 drive to a
modern machine (I know it can be done, but ISTR we established that a
parallel port wasn't quick enough... perhaps with some small amount of
external circuitry like a shift register...)
-ethan
7:32 a.m.
New subject: Help me! Before I take the plunge
On Friday 01 April 2005 10:18, Ethan Dicks wrote:
On Apr 1, 2005 9:25 AM, Doc Shipley <doc at
mdrconsult.com> wrote:
In theory, you can read (and probably write) RX02's, using Tim Mann's
utilities for the Catweasel. I've got an MK3, and intend to try it out
once I get an 8" floppy drive cable made up to test it with. The board
is PCI, so it'll work in most "modern" machines that have PCI slots,
given that you can find or write your own drivers. :)
Pat
--
Purdue University ITAP/RCS --- http://www.itap.purdue.edu/rcs/
The Computer Refuge --- http://computer-refuge.org
Has anybody built the RX emulator described
at
http://www.chd.dyndns.org/rx02/
The page says that RX02 support isn't finished, but that the
RX01 handler is working.
I just wish there were an easy way to attach a real RX02
drive to a
modern machine (I know it can be done, but ISTR we established that a
parallel port wasn't quick enough... perhaps with some small amount
of external circuitry like a shift register...)
7:02 a.m.
New subject: Help me! Before I take the plunge
On Thursday 31 March 2005 23:49, Ethan Dicks wrote:
On Apr 1, 2005 2:07 AM, Lyle Bickley <lbickley at
bickleywest.com> wrote:
Ooops, my goof - My Decmate IIs use RX50 Diskettes, not RX01's. I knew there
was another reason why I sought out DECmate IIs over DECmate Is. I chose the
DECmate II also because it will run CP/M (with the Z80 option) as well as
supporting a HDD. Of the DECmate I, II and III, the II is most "versatile".
Cheers,
Lyle
--
Lyle Bickley
Bickley Consulting West Inc.
http://bickleywest.com
"Black holes are where God is dividing by zero"
The DECMATE I could still be a fun system to own
- and if you can find
DECMATE I system images, both PUTR and TELEDISK will make it easy for you
to create entire copies of diskettes (TELEDISK), format (PUTR) and
transfer files (PUTR).
TELEDISK and PUTR will not solve the problem that a PC can *not* write
RX02-format 8" disks. They are a strange mixed-density beast that can
only be written by RX02-compatible drives. RX01 disks _can_ be
written by a PC with the right FDC chip, but since the DECmate I
shipped with RX02s, not RX01s, its disks are RX02-format.
Possibly one could build RX01 diskette images with the right contents
(with twice as many diskettes) and migrate things over that way, or
emulate the RX02 itself with a PC, but one can *not* just slurp and
burn RX02s directly from a PC. 
8:03 a.m.
New subject: Help me! Before I take the plunge
Lyle Bickley wrote:
On Thursday 31 March 2005 22:49, Ethan Dicks wrote:
--snip--
I believe the DecMate-I could use RL02's. Never saw one set up that way,
but it was in the advertisements.
OS/278 has the necessary patches to deal with the
differences in the
console IOT behavior that was well described in another post. Dunno
about download, but you'd have a problem with the downloaded file,
since the RX02 format can _not_ be written by a PC FDC (it's a hybrid
format that only the RX02 drive (and DEC-compatible 3rd-party
drives/controllers) can write.
I have a couple of DECMATE IIs and I use PUTR (running under DOS) to format
RX50 diskettes and transfer files to the diskettes. I've also used TELEDISK
to copy entire diskettes that I have downloaded and have created virtually
all of the system programs on RX50 diskettes (OS/278, Word Processing, DIBOL,
etc.) that run on a DECMATE II.
I haven't worked with a DECMATE I since the original one I used at work many
years ago - but as I recollect it is not anywhere near as flexible as a
DECMATE II (which has HDD capability - which I've implimented in both my
DECMATE IIs).
The DECMATE I could still be a fun system to own - and
if you can find DECMATE
I system images, both PUTR and TELEDISK will make it easy for you to create
entire copies of diskettes (TELEDISK), format (PUTR) and transfer files
(PUTR).
Cheers,
Lyle
9:55 p.m.
New subject: Help me! Before I take the plunge
On Apr 1, 2005 11:03 AM, Kevin Handy <kth at srv.net> wrote:
I believe the DecMate-I could use RL02's. Never
saw one set up that way,
but it was in the advertisements.
There was a RL278 option, but I have never seen one in person. I
don't know why it was always referred to as an RL02 controller (as
opposed to the RL8A which was routinely used with RL01 drives... I've
done that myself), but perhaps there's a firmware reason for that.
Certainly there's no engineering reason why the controller couldn't
talk to both RL01 and RL02 drives. The cabling is identical, and the
only difference from the device driver's standpoint is number of
cylinders.
-ethan
28 Dec
28 Dec
3:24 p.m.
Tony,
Is the main rectifier diode a black ractangular box with 4 legs, one
labled +, one labled -, and two labeled with s-shaped swigly lines?
Should I get continuity between the s-shaped swigglely lines?
Chad
Tony said:
check forwards from the mains input and at least find
the mains
rectifier diodes and the chopper transistor. Check these for shorts. If
the transistor is OK, and one or more of the diodes is shorted, then
replace the diodes (use something rated at _at least_ 400V 2A) and try
again. If the chopper is shorted, well, you've probably got other
problems too, and _I_ wouldn't want to do much more without a schematic...
4:06 p.m.
Is the main rectifier diode a black ractangular box
with 4 legs, one
labled +, one labled -, and two labeled with s-shaped swigly lines?
Should I get continuity between the s-shaped swigglely lines?
That is actually a diode bridge, four diodes in a single package. Feed
AC in at the pins marked with a sine-wave (the wiggly lines) and get
full-wave rectified DC (modulo diode drops) out at the + and - pins.
"Continuity"? Maybe. If you apply a voltage there - of either
polarity - that's more than about two diode drops, you will see current
flow, through the rectifier and into the rest of the circuit (probably
charging the primary filter caps). Depending on the instrument you
use, this may look like continuity (because your measurement instrument
does not supply enough current to actually charge the caps
significantly), or it may look like a peculiar sort of resistance that
varies depending on which scale you set the meter to.
That's assuming the diode bridge is in full working order. If one of
the diodes has failed open, you'll see the above for applied voltage of
one polarity and no continuity for voltage of the other polarity. If
one of the diodes has failed shorted, you'll see the above description
for one polarity and something similar but with about half the voltage
developed across it for the other polarity. (The latter could well
explain blown fuses, as it amounts to an almost dead short across the
input for half of the AC cycle - it's just a question of whether the
fuse or the diode blows first.)
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29 Dec
29 Dec
9:22 a.m.
Tony,
Is the main rectifier diode a black ractangular box with 4 legs, one
labled +, one labled -, and two labeled with s-shaped swigly lines?
Yes, you've found it Those squiggly lines are little sine waves, the
conventioanl AC symbol. See my other message for how to test it.
Should I get continuity between the s-shaped swigglely
lines?
NO!. Those should be open-circuit both ways!
-tony
10:33 a.m.
Should I get
continuity between the s-shaped swigglely lines?
NO!. Those should be open-circuit
both ways!
1:02 p.m.
Should I
get continuity between the s-shaped swigglely lines?
NO!. Those should be
open-circuit both ways! transformer between it and the mains.
I have never seen an SMPSU with a mains isolation transformer. Yes, I
have seen PSUs that start with a mains transformer (giving, say, 20V),
and then use a switching regulator to bring that down to 5V (or
whatever), but I've never seen one with a 1:1 isolating transformer
(remmeber that 200V electrolytic, there is rectified mains in that PSU).
-tony
7155
days inactive
7616
days old
23 comments
13 participants
participants (13)
-
acme＠gbronline.com -
ard＠p850ug1.demon.co.uk -
doc＠mdrconsult.com -
ethan.dicks＠gmail.com -
fernande＠internet1.net -
kth＠srv.net -
lbickley＠bickleywest.com -
mouse＠Rodents.Montreal.QC.CA -
pat＠computer-refuge.org -
teoz＠neo.rr.com -
vrs＠msn.com -
waisun.chia＠gmail.com -
witchy＠binarydinosaurs.co.uk