Chris M wrote:
>
> though). Soldering iron tips are made of copper, so I
> don't see any reason why I couldn't chisel one down
> for a specific task. Any thoughts? Am I courting
> disaster?
Depends on the tip. The better soldering tips are coated/plated with another
metal, and filing removes that coating. It will still work, but will also
require more maintenance to keep the tip working properly.
> From: davis <davis at saw.net>
>
> > would a decent eye loupe do the trick, as far as
> > determining where the problem lay? Truthfully I've had
> > problem power supplies in the past, and nailed each
> > solder junction (on the underside of the board) w/a
> > hot iron, and it always seemed to work like a charm
> >
> > From what I understand about the problem, just remelting the junctions and not applying solder will do the trick.
Remelting the junctions IF you apply flux to the joint will work fine (if the
joint is not too badly oxidized.) Not applying flux is just playing the lottery
as to the quality of the resoldered joint. A badly oxidized joint probably needs
to go through the solder sucker routine before applying new solder w/flux.
Well, I tried today to bring up my 11/84 - initial
tests are showing me that there is something wrong
with the power supply, an H7200. While the fans run,
there doesn't appear to be any +5v. There is a faint
ticking sound heard from the supply, and when I drop
the power, there is a soft squeaking.
So, before I take the this thing apart, are there any
suggestions where I can look, common failures, etc?
Thanks!
-Ian
>
>Subject: Re: newbie building a scratch-built computer
> From: "Holger Veit" <holger.veit at iais.fraunhofer.de>
> Date: Sun, 05 Aug 2007 12:23:15 +0200 (CEST)
> To: "General Discussion: On-Topic Posts Only" <cctech at classiccmp.org>
>
>
>Tony Duell said:
>> IMHO, more important than the EPROM programmer is an EPROM emulator. This
>> is a box of RAM that connectes to the EPROM socket of the target system
>> (the board you'be just made) and also to a host machine (PC, parallel
>> port, serial port, USB?). YOu can quickly download perogams into the
>> emulator, which then appears exactly as the EPROM does ot the target, and
>> the latter can therefroe run said programs.
>>
>> The advantage over using EPROMs is that you can re-write the RAM as many
>> times as you like (EPROMS have a limited number of program cycles) and
>> rewrite it quickly. Unless your programming is a lot better than mine,
>> you will go mad if you have to wait 20 minutes for an EPROM to be erased
>> and reprogammed. each time you want to make a change!
>
>I haven't so far reached the maximum # of programming cycles for EPROMs in
>any experiment. *) As I recommended you might use EEPROMs instead of
>EPROMs mainly because of their moderate capacity (you won't need PC FLASH
>ROMs with 1MB or more for an 8 bit system) and because they don't need
>erasing in the UV coffin.
Neither have I. I have 2716s, 2732s dating back to early 1980s that
have seen many cycles in many many projects and they are still good.
The thing that seems to kill Eproms is excessive erase times and
reverse polarity.
Allison
>
>*) Maybe your and my programming strategy differs; now with SW emulators
>for almost any old CPU being available ona PC, I tend to test my code in
>an emulator, often with single stepping first before I make a HEX file to
>burn it; even with EEPROMs - the old turnaround cycle of change a byte,
>program, insert and test how far it works is still too long even with RAM
>boxes. Admittedly, in the old times, without PC emulation, I did a lot of
>paper testing work first before burning the stuff into an EPROM; this
>discipline meanwhile degraded...
>
>--
>Holger
All:
I just got my hands on an Ampro LittleBoard/286. It appears to be in
good condition but comes with no manuals or software of any kind. The power
connector is obvious but I would like to get a manual and do some reading
before getting deep into the board.
Googling produces very limited info and no manuals. Does anyone have a
copy of the manual they?d be willing to scan or copy for me? Of course, I?ll
put an information page on my Web site once I?ve collected a bunch of info
on it.
Thanks!
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.altair32.comhttp://highgate.comm.sfu.ca/~rcini/classiccmp
Does anyone here know of an online archive of docs for the Xerox 820-II.
I have a few binders for it and I'm wondering how much of this I need to
run through a scanner.
--
David Griffith
dgriffi at cs.csubak.edu
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
Hi,
There's plenty of free x-assemblers you can find on the net. I run
x-assemblers for 8080/85, 8086/88, 6800, 6809, Z80, 2650, SC/MP and 68000.
They all run on a Windows box. I use two old PCs for my development, one is
a 166Mhz Pentium running Win98 and the other is a 486SX (25Mhz) running
Win3.1. Those machines can run all the x-assemblers and editors necessary
for developing code for most old 8-bit processors.
If I need to get serious and require some ICE then I have an Intel MDS220
and an Intel MDS IV, which can do 8080 and 8085 ICE, respectively.
You can find basic processor schematics on the net and do your initial build
on some breadboard. Depending on the complexity, my final build is usually
wire-wrapped or soldered on veroboard.
Most of the x-assemblers will create an Intel Hex object code file, and you
program your home-brew system to be able to download these files and that's
how you load code into your system. Of course, unless you have a front
panel, you'll need to create a boot EPROM, so access to an EPROM burner is
required. I use an old Microprofessor MFP-1P, which has the EPROM burning
board connected and it burns 2516, 2716, 2532, 2732, 2732A and 2764 chips -
which is all I use on my home-brew systems.
One of the projects I am intending to do is to build a dedicated EPROM
burner, using some old 8-bit processor that can program the above chips as
well as the 2708.
Seeyuzz
River
Andrew Burton wrote:
Well, I'm south-east UK (East Anglia) a few miles from Cambridge.
Regards,
Andrew B
------------------------
When I'm in England (4-5 months a year) I live in Colchester. Maybe we can
get together next time I'm over - mid 2008.
Billy
As of now, my two remaining P112 kits are spoken for (you know who you
are). Plans to make more will depend on getting at least 30 units
preordered. This brings me to VCF West.
I've been asked to do a workshop on the P112 at VCF West . I don't really
know what I'd talk about, but at the very least I guess it would be a
bunch of people soldering together their P112 kits. So far, my schedule
looks good for that. So, please email me at this address or my yahoo
account (cupricus) and let me know what you want.
--
David Griffith
dgriffi at cs.csubak.edu
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
Hi,
I would have thought "scratch-built" implied designing and building your own
home brewed system. Building a kit like the Micro-KIM is not a scratch build
exercise. All it will do is give you more practise in soldering.
If the whole purpose of this exercise is to have an old 8-bit system so you
can program in hex and/or assembler, then you can download an emulator and
play around with it from there. If you mainly want to run things off the
various serial and parallel ports then something like the Micro-KIM would be
useful.
If you want to do the whole lot yourself, then the best way to get "dirty"
is to design your own system, build it yourself (either via wire-wrap or
soldering) and develop your own small debug/monitor program. There's plenty
of information on the Internet to find some small designs that you can use,
and also hints and ideas on debug/monitor code.
I design and build my own systems - not for anything really purposeful, but
mainly for fun. I like to see how many different processor systems I can
build. I also like expanding on old systems, such as the AIM65 or wire-wrap
extra memory/IO boards for Multibus-I, etc.
The easiest oldish 8bit processors to use for a homebrew system would be the
6502, 6802, Z80 and 8085. When you've built one... say a 6502... then the
next fun thing is to build (say) and 8085 system, with similar functionality
and using the Intel family peripheral chips. Then you can get onto the less
common processors like the 2650, 9980... or even the SC/MP.
In any event, whatever path you take, have fun, learn and enjoy yourself.
Seeyuzz
River
