C128: Too little RAM in C64-Mode - Please Help!
Peter Eriksson
I hope everyone's enjoying the holidays! Personally, I'm trying to but
I've just come across a problem that really bugs me (as the subject of
this post suggests). Here's the deal:
When I set up my kid brother's C128 earlier today, I discovered it only
reports 1284 bytes of free RAM in C64-mode (in the startup banner)! In
C128-mode however, 122365 bytes of RAM are reported as free. The computer
itself hasn't been used for a few years, but it has been stored in a dry,
dark and reasonably cool (around 20C which is around... 75F), in its
original packaging.
None of the software I've tried so far (all C64 software) has worked,
apart from "Heist" (which for some reason seems to be working flawlessly).
Can someone please tell me what's wrong with the C128? I'd very much
appreciate any help as I'd really like to get everything going again!
Merry Christmas,
Peter Eriksson
--
[ tall enough to catch the stars ]
pe...@acc.umu.se - icq uin: 13638622
kie...@theriver.com
I discovered it only
>reports 1284 bytes of free RAM in C64-mode (in the startup banner)! In
>C128-mode however, 122365 bytes of RAM are reported as free.
I suspect you're short in C128 mode also;the C64 actually checks the RAM
for free memory.The C128 doesn't check.the "122365 BYTES FREE" messege is
in ROM IIRC
keith
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Peter Eriksson
> I suspect you're short in C128 mode also;the C64 actually checks the RAM
> for free memory.The C128 doesn't check.the "122365 BYTES FREE" messege is
> in ROM IIRC
Well, I've done some more extensive testing and come to these conclusions:
When I'm in C128-mode and type "print fre(0)", the result is "58109". The
same figure for the C64-mode is "1282", but when I use the "Action Replay
5.0" cartridge (which also forces the C128 to enter C64-mode), "print
fre(0)" returns -26627 bytes! Yeah, that's a negative number of bytes.
Either way, the amount of RAM reported in all cases is too low.
Keith, do you or anyone else know what's going on here? How do I deal
with this problem?
Kind regards,
Peter
Nicolas Welte
> When I set up my kid brother's C128 earlier today, I discovered it only
> reports 1284 bytes of free RAM in C64-mode (in the startup banner)! In
> C128-mode however, 122365 bytes of RAM are reported as free. The computer
One or more of the RAM chips in bank 0 are bad and must be replaced. There are
test programs to determine which one it is, but those come on a cartridge.
C128 mode does not do a memory test, so it always reports the full number of
BASIC bytes, but C64 mode will stop at the first bad byte.
Since the first bad byte is after the end of the used BASCIC RAM, you can run
a small test yourself. Now I'm not sure where that byte is exactly, but it is
very probably at location 2049+1284=3333 (ohh, what a magic number!). So if
you run this test:
R=3333:POKE R,0:?PEEK(R):POKE R,255:?PEEK(R)
and you don't get the numbers 0 and 255 printed out, then please post the
numbers and I can look up the bad chip. If you get those numbers, 3333 is not
the bad byte, so you could try a few numbers around that.
Nicolas
PS: Merry Christmas to everybody!
BlackJack
> When I'm in C128-mode and type "print fre(0)", the result is "58109".
> The same figure for the C64-mode is "1282", but when I use the "Action
> Replay 5.0" cartridge (which also forces the C128 to enter C64-mode),
> "print fre(0)" returns -26627 bytes! Yeah, that's a negative number of
> bytes. Either way, the amount of RAM reported in all cases is too low.
No, the fre(0) function of the C64 is somehow "defect": it returns the
unsigned 16 bit value as as signed one, which means values higher than
32768 are returned as negative numbers.
To get the correct value you have to add 65536 to the result if it was
negative.
But this won't help in your situation because the Action Replay bypasses
the memory test just like the C128 ROM does.
BTW: To define a corrected version of the fre(0) routine you may use this:
10 DEF FN FR(X) = FRE(0) - (65536 * (FRE(0) < 0))
.
.
.
42 PRINT FN FR(0)
Ciao,
Marc 'BlackJack' Rintsch
Chris
Have you tried reseating the ram? If the chips are socketed you can just
pull them up out of their sockets and carefully put them back in. Be
careful of static shock and of course, unlug the computer completely before
pulling chips. If the C-128 works like an old 386 that used DRAMS for me in
the past then the C-128 will still boot with only some of the chips in
place. This way if after your reseat them all and you still have trouble,
then you can isolate which chip is bad. I'm sure you can get replacements
cheap on the net.
Resocketing the CPU may also help. In any event be super careful of the pins
because I've bent plenty in my day without realizing it.
Happy holidays,
chris
--
"Peter Eriksson" <pe...@acc.umu.se> wrote in message
news:Pine.LNX.4.42.011225...@mao.acc.umu.se...
Peter Eriksson
OK, I havn't studied German for a while so I guess I better stick to
English for the time being :) Thanks for your reply - I've typed in
the RAM-test of address 3333 a few minutes ago, and you were quite
right; there is something weird about that address.
I noticed that I got different values from the PEEK() statements on
occasion, both in C64 and C128 mode so I took the liberty of adding a
GOTO jump into the program, looping the whole shebang to look for
different values. Here's what I got:
32, 223
0, 223
0, 255
32, 255
Although 0, 255 did actually appear, I take it all those other values
report that something is really wrong?
(Just for the record, I did try changing the address from 3333 to 3329
to 3339, and all the other addresses seem to be working fine. In this
range, only address 3333 is showing these weird results)
Nicolas, I have never ever dealt with a problem like this before.
Could you please explain to me on a real basic level what's wrong and
what has to be done? I'd very much appreciate it!
Frohe Weinnachten aus Umeå - Schweden,
Peter :)
--
Tall Enough to Catch the Stars
pet...@hotmail.com
Peter Eriksson
and thank you for your reply. I had no idea the Commodore 64 carried
bugs like the one you're describing. Nonetheless, it was interesting
reading! Thanks. :)
Merry Christmas to you as well!
Kind regards,
Peter
Raymond Day
and piggybacking it on top of the old one will fix it. Maybe only one ram
chip is bad. So you could just take one good ram chip and piggyback it on
top of one of the ram chips out of 8 in the C64 bank. Then tern on the 128
and see if that works. Then you know that if the bad ram chip and can
desolder it or just solder the new ram chip piggybacked on top of the bad
one. When you piggyback it for test make sure the pins are snug.
-Raymond Day
Peter Eriksson
thank you for your reply here at comp.sys.cbm. I've seen other threads
in this newsgroup describing similar problems, and it seems this "piggybacking"
approach is quite popular.
Now, I take it the term "piggybacking" actually means putting one chip on
top of the other? Raymond, you're saying I should make sure that the pins
of the upper RAM-chip are snug, but I fail to see how I could get those
pins snug if the actual chip is put on top of the other? I mean, the pins
of the upper chip has to be *longer* to reach the socket/motherboard the
original RAM-chip is placed on, right? (otherwise the pins would simply
not reach the socket/motherboard).
Finally, you're referring to "one of the RAM chips out of eight in the C64
bank". Does this "bank" comprise of eight physical slots? How many banks
are there? (Two?) Which of them is used by the C64 mode (in other words,
how do I recognize it)?
Kind regards,
Peter (in Sweden)
Nicolas Welte
> I noticed that I got different values from the PEEK() statements on
> occasion, both in C64 and C128 mode so I took the liberty of adding a
> GOTO jump into the program, looping the whole shebang to look for
> different values. Here's what I got:
>
> 32, 223
> 0, 223
> 0, 255
> 32, 255
>
> Although 0, 255 did actually appear, I take it all those other values
> report that something is really wrong?
The fact that you sometimes got a 32 when there should be a 0, and a 223
instead of a 255 (255-223=32) means that the memory bit that is responsible to
hold a value of 32 at address 3333 is acting totally crazy. It just doesn't
store what it should, it returns a random state.
In the C128 and plastic C128D computers, there is a single RAM chip that is
responsible for storing this bit. A decimal value of 32 corresponds to bit 5
in binary notation (since 2^5=32), so I'll check my service manual for the
chip location: U43 holds this bit in RAM bank 0. If you had a metal C128DCR,
this bit would be stored in U39, together with the bits 4,6 and 7.
Since this question turns up sometimes, I'll make a table now for future
reference. This is also useful if you have a RAM test program that outputs
chip locations, which are made for the first generation C64, and you want to
repair one of the other computer types.
C64 with 8 RAM chips: RAM chip type 64kbit x 1: e.g. 4164
bit
0 U21
1 U9
2 U22
3 U10
4 U23
5 U11
6 U24
7 U12
C64 with 2 RAM chips: RAM chip type 64kbit x 4: e.g. 41464
bit
0,1,2,3 U10
4,5,6,7 U9 on large boards / U11 on small boards
C128 and plastic C128D: RAM chip type 64kbit x 1: e.g. 4164
bank 0 1
bit
0 U38 U46
1 U39 U47
2 U40 U48
3 U41 U49
4 U42 U50
5 U43 U51
6 U44 U52
7 U45 U53
C128DCR: RAM chip type 64kbit x 4: e.g. 41464
bank 0 1
bit
0,1,2,3 U38 U40
4,5,6,7 U39 U41
> Nicolas, I have never ever dealt with a problem like this before.
> Could you please explain to me on a real basic level what's wrong and
> what has to be done? I'd very much appreciate it!
I hope I made clear what is wrong, you have a bad RAM chip that causes this
single memory bit to read back random values. The cure is easy, the RAM chip
has to be replaced. First of all, you need to get a proper replacement. If you
need one of the 4164 chips, you can also use a 41256 instead, those are easy
to get from old PC mainboards, or other old computers. 4164 are so old that
they can be hard to find. Since the RAM chip number prefixes often change from
manufacturer to manufacturer, you can ignore this and just look that the chip
has 16 pins and the number ends in 64 or 256. If you have to use a '256 chip,
you have to solder a short piece of wire between pins 1 and 16 of that chip
(these are the pins just left and right of the alignment notch on the chip).
This mod will make the chip look just like a '64 chip to the system.
To remove the old chip at U43, you can just cut off the legs of the chip first
with a small wire cutter or small scissors, and take care not to damage the
circuit board. Then hold each of the stuck pins with tweezers and heat up the
solder joint on the board, and pull out the pin. Do this for each pin, and
then clean out the holes in the mainboard. If you have a solder sucker, heat
up the solder and then suck it out. If you don't have one, some people report
good success with a syringe needle that just fits the hole. Insert it while
the solder is hot, and keep rotating the needle a little while the solder
cools down. This will leave a clean hole. I know, not everybody has syringes
at home. I also don't have them, I only heard of this technique :-) Then
insert the new chip and solder it in place (and add the wire, if you have a
'256 chip). If you're unsure about your abilities in soldering, use a chip
socket for the new chip.
Unfortunately there might still be another bad chip that you will only
discover once you have the good one in place, and the RAM test advances to
other adresses. Then the whole procedure starts from the beginning.
> Frohe Weinnachten aus Umeå - Schweden,
Danke, und viel Glück bei der Reparatur!
Nicolas
Peter Eriksson
thank you so much for helping me out - not only has your reply been
quick, but also real pedagogical (as in "pretty easy to understand"
:).
OK, so I have to find a replacement RAM chip for the current one at
U43 (I take "U43" is printed on the motherboard). Nicolas, you mention
that
these chips (4164 and their "cousins" 41256) are usually found in "old
PC mainboards" and old computers in general. Just how old do you mean
by "old"? The 86386 generation? 286? AT? XT?
One of the largest distributors for electronic spare parts in Sweden
is a company called "Elfa" (http://www.elfa.se/ - the site should be
available in English). Although my search at Elfa for "41256" didn't
come up with anything, I've actually found a circuit called "4164-12",
labeled as "dynamic RAM". Here are the specifications from Elfa:
Name: 4164-12
Organization: 64 K×1
Accesstime (ns): 150
Capsule: DIL16
Nicolas, is this what I'm looking for? "4164-12"? Elfa is selling this
circuit for 131 SEK, roughly equivalent of 15 EUR. Is this the market
price, or will I be paying too much? (it's not that I can't afford 15
EUR, it's more that I don't have any idea how many chips that have to
be replaced - from what I understand, it can be just one but it might
as well be ... any number up to sixteen, in the event all of the chips
in the C128 will be broken?)
[ About the actual replacement technique ]
Thank you for taking me thru all this, Nicolas! I think it's becoming
more and more appearant I have to buy some soldering tools (including
the tin sucker). Man, it has been ages since I ever held one; back in
junior high (around 1990) I took a few classes of electronics in
school, so this could get interesting... hm, to say the least. :)
(Always heat the circuits first, then apply the actual soldering/tin,
right? :)
I have one final question, Nicolas (if that's okay with you). You're
saying I can use a "chip socket for the new chip". Would that be a
chip socket that will eventually let me just (carefully) push the
replacement chip into place (and, should it break again, just pull it
out with a pair of plyers or something similar)? Kind of like the
sockets holding the Kickstart chips in Amiga computers?
Nicolas, I will try to make an inventory of the stuff I need to pull
this off! I really appreciate your help on this. Believe me, you've
taken my knowledge in C128 (and 64) hardware lightyears away from my
past knowledge in just a few hours! :)
Vielen Dank für die ganze Hilfe ich kann erhalten (hey, pretty good,
huh? :),
Peter
Sam Gillett
Nicolas Welte wrote ...
[snip]
>then clean out the holes in the mainboard. If you have a solder sucker,
heat
>up the solder and then suck it out. If you don't have one, some people
report
>good success with a syringe needle that just fits the hole. Insert it while
>the solder is hot, and keep rotating the needle a little while the solder
>cools down. This will leave a clean hole. I know, not everybody has
syringes
>at home. I also don't have them, I only heard of this technique :-)
A machinist's scribe, or a mechanic's seal pick (looks like a small ice
pick) will also work. These can be found at hardware stores and do not
require a prescription to purchase. :-) Insert it gently while the
solder is hot, and rotate slowly as solder cools. Do not force the tool as
circuit boards are easy to damage.
Best regards and Happy New Year!
Sam Gillett aka Mars Probe @ Starship Intrepid 1-972-221-4088
Last 8-bit BBS in the Dallas area. Commodore lives!
Mike Lee
Peter Eriksson wrote:
> pe...@acc.umu.se - icq uin: 13638622H
Hi there,
I have an action replay cart in my 128, but no matter, when oyu are on 64 mode,
ofr free ram do it this way to get aproper reading of free ram, ?FRE(0)+65536
this is the way to get a proper full memory reading.....
Mike....
Alex Eisenhut
> PC mainboards" and old computers in general. Just how old do you mean
> by "old"? The 86386 generation? 286? AT? XT?
>
garbage.
Back in the day, 30 pin SIMMs also had 41256s soldered on them.
> Nicolas, is this what I'm looking for? "4164-12"? Elfa is selling this
> circuit for 131 SEK, roughly equivalent of 15 EUR. Is this the market
> price, or will I be paying too much? (it's not that I can't afford 15
Ridiculously expensive.
When you have determined your needs, e-mail me, I have BAGS of 41256s
and 4164s.
I can send you a few.
Peter Eriksson
> When you have determined your needs, e-mail me, I have BAGS of 41256s
> and 4164s.
> I can send you a few.
Thanks a bunch, Alex! I thought I'd go downtown today (or tomorrow)
and get the tools I'm missing for uhm... open heart surgery of the
C128. :) Hopefully, I can get hold of a few 4164 RAM-chips myself, but
in case I can't I'd very much appreciate it if I could buy a few from
you. Hm, that would be a pretty cool reason for me to exchange some
SEK into EUR as well, right? :)
Alex, I'll keep you updated! Again, thank you for your kindness!
Frohe Weinnachten,
Peter (aus Umeå, Schweden)
Peter Eriksson
> A machinist's scribe, or a mechanic's seal pick (looks like a small ice
> pick) will also work. These can be found at hardware stores and do not
> require a prescription to purchase. :-)
Well... perhaps not a prescription, but at least a description (or
better yet, a *translation*) :). I've never heard of the word "scribe"
used in another context than "writing" (as a verb) and "people who are
writing ("writers")" (as a noun). Not even dictionary.com comes up
with a better explanation, Sam. :)
Anyway, I thought I should go for the real deal (with a soldering/tin
sucker). A nationwide hardware store sells a couple of models
depictured at this URL:
http://www.clasohlson.com/images/products/S/hi/B/HD3_302074_hi_S.jpg
Sam, can you please have a look and tell me what you think? (It looks
like the tip of this... hm, "sucker" (no pun intended :) is made out
of plastic?!)
Now, as for the soldering-iron itself, I thought I'd pick one driven
by 15W. Would that be sufficient for jobs like this one (desoldering
chips and soldering replacement parts)? I have a gut feeling too much
heat can do more harm than good, so just do be on the safe side I
though 15W should to the trick. Any comments on this?
Finally, I know there's a liquid you pour on the soldering tin you're
using to lower the melting temperature of the tin. Is this something
you'd recommend using in situations like this one?
Although I'm kinda excited about this, I'm still a bit nervous about
all this. This would be my first go at anything like this, and it's my
kid brother's C128. I really want to do this right, guys. :)
Kind regards,
Peter
--
Merry Christmas and a Happy New Year!
pet...@hotmail.com
Nicolas Welte
> these chips (4164 and their "cousins" 41256) are usually found in "old
> PC mainboards" and old computers in general. Just how old do you mean
> by "old"? The 86386 generation? 286? AT? XT?
Mostly on PC/XT and old AT computers. New ATs and 386 used SIPP and SIMM
sockets already.
> Nicolas, is this what I'm looking for? "4164-12"? Elfa is selling this
> circuit for 131 SEK, roughly equivalent of 15 EUR. Is this the market
That's way too expensive. You pay so much, because the chip is long out of
production, it became an expensive spare part. Try to get a used one, or take
Alex' offer for a bag of those chips :-) I also think I have a small bag of
those chips left, so before you have to buy the expensive ones, I can look
through my inventory.
> be replaced - from what I understand, it can be just one but it might
> as well be ... any number up to sixteen, in the event all of the chips
> in the C128 will be broken?)
That is it, you don't know now how many chips you need. It won't be as many as
16, with a little bit of luck you have only this single bad chip. But you
never know.
> [ About the actual replacement technique ]
> (Always heat the circuits first, then apply the actual soldering/tin,
> right? :)
Yes, you remember the correct technique :-)
> I have one final question, Nicolas (if that's okay with you). You're
> saying I can use a "chip socket for the new chip". Would that be a
> chip socket that will eventually let me just (carefully) push the
> replacement chip into place (and, should it break again, just pull it
> out with a pair of plyers or something similar)? Kind of like the
> sockets holding the Kickstart chips in Amiga computers?
That's exactly the type of sockets I meant. The kickstart sockets are of a
cheap kind, but they will do for about 100 chip swaps easily. There are
slightly more expensive precision sockets with round pins, you can use them if
you want to have something that is made for eternity.
> Vielen Dank für die ganze Hilfe ich kann erhalten (hey, pretty good,
> huh? :),
Bitteschön, gern geschehen. But now it shows that you didn't use your German
for quite some time :-)
Nicolas
MagerValp
PE> Anyway, I thought I should go for the real deal (with a
PE> soldering/tin sucker). A nationwide hardware store sells a couple
PE> of models depictured at this URL:
PE> http://www.clasohlson.com/images/products/S/hi/B/HD3_302074_hi_S.jpg
PE> Sam, can you please have a look and tell me what you think? (It
PE> looks like the tip of this... hm, "sucker" (no pun intended :) is
PE> made out of plastic?!)
The blue/silver one is great, I've used it.
PE> Now, as for the soldering-iron itself, I thought I'd pick one
PE> driven by 15W. Would that be sufficient for jobs like this one
PE> (desoldering chips and soldering replacement parts)? I have a gut
PE> feeling too much heat can do more harm than good, so just do be on
PE> the safe side I though 15W should to the trick. Any comments on
PE> this?
If you don't want to buy a soldering station with adjustable tempera-
ture, yeah, err on the side of caution. Desoldering requires a bit
more heat than soldering though, so maybe a 25W one would be better.
PE> Finally, I know there's a liquid you pour on the soldering tin
PE> you're using to lower the melting temperature of the tin. Is this
PE> something you'd recommend using in situations like this one?
Solder flux is good to have around, but it should be the non-acidic
kind iirc. The strong stuff might eat through your PCB :)
--
___ . . . . . + . . o
_|___|_ + . + . + . . Per Olofsson, konstnär
o-o . . . o + Mage...@cling.gu.se
- + + . http://www.cling.gu.se/~cl3polof/
Helge Wunderlich
>Well... perhaps not a prescription, but at least a description (or
>better yet, a *translation*) :). I've never heard of the word "scribe"
>used in another context than "writing" (as a verb) and "people who are
>writing ("writers")" (as a noun). Not even dictionary.com comes up
>with a better explanation, Sam. :)
Maybe Norwegian is easier ? "Rissenål" is the Norwegian word. It is a
tool used for scribing, or scratching, marks into hard surfaces, such
as metal. Any small, pointy tool to put into the hole to prevent the
solder to flow back into the hole will do.
>Anyway, I thought I should go for the real deal (with a soldering/tin
>sucker). A nationwide hardware store sells a couple of models
>depictured at this URL:
>
>http://www.clasohlson.com/images/products/S/hi/B/HD3_302074_hi_S.jpg
A word of caution on these: They produce a powerful recoil, causing
the tip to snap forward as you "fire" them. The impact combined with
the strong vacuum and the heat *might* result in the entire hole
plating being sucked out of the main board. If the board is a
multi-layer board (more than two layers), this is fatal to the board.
Some of these tools claim to be "recoil free", but as long as they are
designed with a piston being flung back by a spring, they can not
possibly be recoil free.
A much better solution is to use solder wick ("avloddingslisse" in
Norwegian). Not as quick and elegant as the "cannon", but much more
gentle on the main board. Clas Ohlson sells that too.
>Sam, can you please have a look and tell me what you think? (It looks
>like the tip of this... hm, "sucker" (no pun intended :) is made out
>of plastic?!)
Yes, they're plastic. PTFE (aka Teflon) to be precise. PTFE can take a
lot of heat, and nothing sticks to it, so the solder metal will not
clog them. The tip will take damage if left in direct contact with the
soldering iron for any length of time. After a lot of use, they will
become fringed, but replacement tips are available.
>Now, as for the soldering-iron itself, I thought I'd pick one driven
>by 15W. Would that be sufficient for jobs like this one (desoldering
>chips and soldering replacement parts)?
15 W is about right. Ideally, you should use thermostat controlled
iron with about 40 W of power, but they are quite expensive. 15 W is
only just strong enough to use solder wick properly, but if you get
the thinnest wick, it will work fine. To be absolutely sure, you may
want to let the board cool off for a couple of minutes after doing two
or three solder points. Cut off the used part of the wick often, as it
will suck heat from the iron too.
>I have a gut feeling too much
>heat can do more harm than good, so just do be on the safe side I
>though 15W should to the trick. Any comments on this?
Actually, too cool is just as bad as too hot. You'll end up using too
much time for the solder, and the heat will flow far into the board
and components. A solder operation should ideally last about 2-4
seconds.
>Finally, I know there's a liquid you pour on the soldering tin you're
>using to lower the melting temperature of the tin. Is this something
>you'd recommend using in situations like this one?
Stay far away. This is plumber's stuff. It may be highly corrosive,
and eat your main board to shreds within a few months. There are types
suitable for electronics use, but the flux contained in the solder is
all you need.
>Although I'm kinda excited about this, I'm still a bit nervous about
>all this. This would be my first go at anything like this, and it's my
>kid brother's C128. I really want to do this right, guys. :)
You'll be his hero forever. There are not many people on this planet
that are capable of repairing a computer main board, you know :-)
--
Helge Wunderlich
Please delete obvious part of email address to send email.
Charles Richmond
>
> [snip...] [snipo...] [snip...]
>
> Although I'm kinda excited about this, I'm still a bit nervous about
> all this. This would be my first go at anything like this, and it's my
> kid brother's C128. I really want to do this right, guys. :)
>
would recommend that you replace it with a low-profile socket. Then
the new chip would be socketed, in case you have to replace it some
time in the future...
--
+-------------------------------------------------------------+
| Charles and Francis Richmond <rich...@plano.net> |
+-------------------------------------------------------------+
Sam Gillett
Peter Eriksson wrote ...
>Well... perhaps not a prescription, but at least a description (or
>better yet, a *translation*) :). I've never heard of the word "scribe"
>used in another context than "writing" (as a verb) and "people who are
>writing ("writers")" (as a noun). Not even dictionary.com comes up
>with a better explanation, Sam. :)
I found this in a dictionary:
scriber
noun
1. A sharply pointed tool used for marking lines, as on wood, metal, or
ceramic. Also called scribe.
Helge also had a good definition. :-)
>Anyway, I thought I should go for the real deal (with a soldering/tin
>sucker). A nationwide hardware store sells a couple of models
>depictured at this URL:
>
>http://www.clasohlson.com/images/products/S/hi/B/HD3_302074_hi_S.jpg
>
>Sam, can you please have a look and tell me what you think? (It looks
>like the tip of this... hm, "sucker" (no pun intended :) is made out
>of plastic?!)
As Helge mentioned, the recoil from spring loaded solder suckers can be a
problem. I prefer the type that is simply a rubber bulb with a teflon tip.
I find it easier to control. Many technicians prefer the spring loaded
models. I have used both kinds and both types will work.
The teflon tips are fairly durable if not left in contact with the tip of
the soldering iron longer than necessary. And they do not get clogged with
solder as easily as the old style stainless steel tips.
>
>Now, as for the soldering-iron itself, I thought I'd pick one driven
>by 15W. Would that be sufficient for jobs like this one (desoldering
>chips and soldering replacement parts)? I have a gut feeling too much
>heat can do more harm than good, so just do be on the safe side I
>though 15W should to the trick. Any comments on this?
For working with IC's a 25 watt iron would be the largest that you might
want to use, and 15 watt the smallest. I prefer a 20 watt iron for most
printed circuit board work. For IC's you need a small diameter tip on the
iron. I prefer the cone shaped tips. Many technicians prefer the
screwdriver shaped tips.
>
>Finally, I know there's a liquid you pour on the soldering tin you're
>using to lower the melting temperature of the tin. Is this something
>you'd recommend using in situations like this one?
Most liquid fluxes are acid, and should not be used in electronic work. Use
a solder with a rosin flux core. A small diameter solder is best for what
you will be doing, as it is easier to control the amount of solder applied.
If you can't find solder with a rosin core, use a rosin paste type of flux.
The definition of flux as used above isn't in most dictionaries. Flux as
used in soldering is a chemical used to clean the surfaces being soldered
and/or improve adhesion of solder to the surfaces being soldered.
>
>Although I'm kinda excited about this, I'm still a bit nervous about
>all this. This would be my first go at anything like this, and it's my
>kid brother's C128. I really want to do this right, guys. :)
Work carefully, and avoid getting in a hurry. A little practice with the
soldering iron before you start on the computer might be a good idea. Find
a scrap circuit board, perhaps in an old radio. Practice unsoldering and
soldering on that. Then you will be ready for the C-128.
Best regards, and Happy New Year!
Alex Eisenhut
> Thanks a bunch, Alex! I thought I'd go downtown today (or tomorrow)
> and get the tools I'm missing for uhm... open heart surgery of the
> C128. :) Hopefully, I can get hold of a few 4164 RAM-chips myself, but
> in case I can't I'd very much appreciate it if I could buy a few from
> you. Hm, that would be a pretty cool reason for me to exchange some
> SEK into EUR as well, right? :)
No no no. No charge. Just figure out what you need. As long as you can
wait a month for surface mail...
>
> Alex, I'll keep you updated! Again, thank you for your kindness!
I'm cleaning up my electronics stuff. There's very little chance I'll
need bags of 4164s or 41256s anytime soon. I prefer core memory or
bubble memory for all my hacking needs... :) It's just more fun to give
stuff to people who need it than to throw it away. I also have various
static RAM chips, like 6264 and 62256s.
>
> Frohe Weinnachten,
> Peter (aus Umeå, Schweden)
Happy Holidays!
mike
> A machinist's scribe, or a mechanic's seal pick (looks like a small ice
> pick) will also work. These can be found at hardware stores and do not
> require a prescription to purchase. :-)
Another options if to use round toothpicks.
>
>Although I'm kinda excited about this, I'm still a bit nervous about
>all this. This would be my first go at anything like this, and it's my
>kid brother's C128. I really want to do this right, guys. :)
>
It sounds like you are new to soldering. I would recommend that you practice
on an old/no good pc board before working on the 128 board. Also, if can find
one, a dual wattage soldering iron is good. I use one that you can switch
between 15 and 30 watts.
Mike
Matthew Montchalin
|>Although I'm kinda excited about this, I'm still a bit nervous about
|>all this. This would be my first go at anything like this, and it's my
|>kid brother's C128. I really want to do this right, guys. :)
|
|It sounds like you are new to soldering. I would recommend that you
|practice on an old/no good pc board before working on the 128 board.
|Also, if can find one, a dual wattage soldering iron is good. I use
|one that you can switch between 15 and 30 watts.
What is the appropriate price that a person should pay for a soldering
iron? What kind of price is the one to look for, regarding acid free
solder?
Peter Eriksson
sorry for this reply taking so long. I've had so much spare time I didn't
know just how to handle it. :)
> No no no. No charge. Just figure out what you need. As long as you can
> wait a month for surface mail...
Guess what? I've just received an offer just like yours from another guy
here in Sweden. Hopefully, I won't have to leach from either one of you guys
as I really hope to find a source of 4164 chips myself; I can't think of one
single Usenet newsgroup that is filled with some much positive thinking and
generousity as comp.sys.cbm.
Alex, no matter if I will ask you to send me any RAM chips for my brother's
C128 or not, I still feel I'm in debt to you. :) I'll keep you posted on the
development!
Kind regards,
Peter
--
Seasons Greetings from Umeå, Sweden - The European Union
pe...@hotmail.com
Peter Eriksson
well - the response to my problems has been overwhealming, to say the least!
I wouldn't even have dreamed of getting some many people involved in my
problems. Helge, you are certainly one of them, and I'm real grateful for
it! I've taken what you and Sam has written into account and posted a reply
to Sam's post parallel to this one in comp.sys.cbm.
Helge, can you please give me the article number of the soldering wick you
are mentioning (if it's not too much trouble)? I'd really like to consider
all my alternatives before I actually do this! :)
(I've never actually thought that a soldering process that isn't warm enough
can do more harm than good, considering it would take more time for the
tin/solder to actually melt - thanks for letting me in on the secret, Helge.
:) I don't think of would have thought about it myself if it wasn't for you
pointing it out)
Oh yeah, I have one final question. :) Helge, you're saying that "the flux
contained in the solder" is all I need. To clarify this - does the solder
itself contain this miracle flux? I don't have to buy anything besides the
actual tin/solder? In junior high, I remember we used a liquid of some kind
(which my teacher called "fluss" - I guess that would translate as "flux")
when soldering electronics (stuff like "running lights" and some simple
burgler alarms).
> You'll be his hero forever. There are not many people on this planet
> that are capable of repairing a computer main board, you know :-)
Thanks, Helge. :) Although I wouldn't go as far as saying I'll be his hero
forever, I hope to make him glad. After all, we've had so much fun with this
C128 I feel I owe both him, myself and the actual computer to give something
back (I got the C128 myself in 1986 - my brother got it from my when I got
my Amiga 500). I bought a C1581 a while ago so I thought I'd compile a whole
new library of C64/128 programs on 3.5" floppies. Pretty neat, huh? :)
Happy New Year, Helge!
Kind regards,
Peter
PS: Ja, jeg snakker lite norsk. På somrarna jobbar jag extra på ett
utomhusbad här i Umeå och vi har ganska många norska turister från Mo-i-Rana
här. :)
--
Seasons Greetings from Umeå, Sweden - the European Union
Peter Eriksson
thanks for the tip. I've heard others talk about low-profile sockets, and
the idea itself does make a lot of sense (it makes any future replacement
operations a lot easier, plus it won't risk damaging the RAM chip itself
during the soldering process).
Charles, do you know if the C128 case is high enough to fit these sockets
plus the chips themselves?
Kind regards,
Peter
Helge Wunderlich
>Helge, can you please give me the article number of the soldering wick you
>are mentioning (if it's not too much trouble)? I'd really like to consider
>all my alternatives before I actually do this! :)
20-810-15 is the number in my Norwegian 2001 catalogue. They have
three different thicknesses. This is the thinnest one, which is best
if you are using a 15 W soldering iron.
I just saw a nice soldering iron in the catalogue: 30-7742. It is 50 W
with adjustable temperature control and costs NOK 400. Seems like a
nice tool, but maybe overkill for one single memory chip.
>Oh yeah, I have one final question. :) Helge, you're saying that "the flux
>contained in the solder" is all I need. To clarify this - does the solder
>itself contain this miracle flux?
Yes, that's correct. One or more tiny channels of flux inside the
solder. This causes a little flux to be released whenever you apply
some solder. This is also why you should cut solder with a pair of
pliers (or other cutting tool), not pull it. Pulling will stretch the
metal and not the flux, resulting in parts of the solder having no
flux in it.
>I don't have to buy anything besides the
>actual tin/solder?
Correct. To be sure, check that the solder is "suitable for
electronics". Some types contain corrosive flux, but those are
generally only available in thicker gauges.
Thinner solder is better, but more expensive. 0.8 mm is good for your
job.
>In junior high, I remember we used a liquid of some kind
>(which my teacher called "fluss" - I guess that would translate as "flux")
>when soldering electronics (stuff like "running lights" and some simple
>burgler alarms).
If the objects to be soldered are badly corroded, or otherwise have
poor "solderability", it might make sense to use some extra flux. Your
ojects are already nicely covered in solder, so there is no use for
extra flux.
>Happy New Year, Helge!
Thanks, the same to you.
Charles Richmond
>
> Hi Charles,
>
> thanks for the tip. I've heard others talk about low-profile sockets, and
> the idea itself does make a lot of sense (it makes any future replacement
> operations a lot easier, plus it won't risk damaging the RAM chip itself
> during the soldering process).
>
> Charles, do you know if the C128 case is high enough to fit these sockets
> plus the chips themselves?
>
an extra chip-thickness at the most...
jaseinblack
"Charles Richmond" <rich...@ev1.net> wrote in message
news:3C2FFCED...@ev1.net...
> I believe that you can fit the socket in there...the socket should add
> an extra chip-thickness at the most...
My C128 has had a RAM chip replaced before, and this is socketed, so it
should be OK.
Jase
jaseinblack
"Chris" <chri...@home.com> wrote in message
news:pb8W7.329956$5A3.12...@news1.rdc2.pa.home.com...
> If the C-128 works like an old 386 that used DRAMS for me in
> the past then the C-128 will still boot with only some of the chips in
> place.
This doesn't work - all you get is a blank screen :-(
Jase
jaseinblack
"Peter Eriksson" <pet...@hotmail.com> wrote in message
news:7cf73dc3.01122...@posting.google.com...
>> Finally, you're referring to "one of the RAM chips out of eight in the
C64
> bank". Does this "bank" comprise of eight physical slots? How many banks
> are there? (Two?) Which of them is used by the C64 mode (in other words,
> how do I recognize it)?
As far as I can tell the C64 row of chips are the ones marked U38-U44.
Jase
jaseinblack
are
> test programs to determine which one it is, but those come on a cartridge.
> C128 mode does not do a memory test, so it always reports the full number
of
> BASIC bytes, but C64 mode will stop at the first bad byte.
By coincidence, I got my 128 down from the loft the other day and had the
same problem - except I had 772 Basic bytes free. Which isn't a great deal
:-)
I too ran a program in C64 mode that went through a part of memory poking a
value in and seeing if the same value came out - it didn't :-(
I found a C128 diagnostics disk in D64 format from the web, copied onto a
5.25" disk and ran the C64 diagnostic test. It said that RAM chip U38 was
faulty. If you want a copy of the D64 image, do let me know. It was quite
useful, although didn't run 100% properly (presumably due to the iffy RAM).
I cut a 4864 from an old C64 and attempted to solder that onto the legs of
the duff chip - it didn't work, making it worse - the machine would display
garbage on screen and not give me a cursor.
I thought that either the RAM chip was broken (quite probably after being
cut from the old C64 and soldered clumsily onto the 128's board) or it was
the wrong chip.
I found some 4124s for sale at wwwrs.com (IIRC) and have ordered a couple of
these, at almost 5GBP each, so I'm waiting for those. I'm going to solder a
DIL socket on to the C128 should it need replacing in the future.
It remains to see if it all works!
Jase
Peter Eriksson
although I'm sorry to hear about your C128 not doing too well, it *is* still
a pretty strange coincidence. :) Jase, I think it would be real interesting
running this diagnostics analysis myself. Can you please point me to the
source of the program you're using?
Best of luck with the repairs (and a happy new year!),
jaseinblack
> although I'm sorry to hear about your C128 not doing too well, it *is*
still
> a pretty strange coincidence. :) Jase, I think it would be real
interesting
> running this diagnostics analysis myself. Can you please point me to the
> source of the program you're using?
It's at http://www.zimmers.net/cbmpics/c128s.html - on this page near the
bottom is a link labelled "Diagnostics 128."
Not that I know how it works, but if you get stuck give me a shout!
> Best of luck with the repairs (and a happy new year!),
Do let us know how you get on with your repair.
Jase
mike
<n...@chance.com> writes:
>I found a C128 diagnostics disk in D64 format from the web,
How about posting the url?
Mike
jaseinblack
"mike" <green...@aol.comnone> wrote in message
news:20020102145500...@mb-cv.aol.com...
> How about posting the url?
I would have done initially, but didn't know if anyone was bothered, so
saved myself the effort :-)
It's in a separate post, and here: http://www.zimmers.net/cbmpics/c128s.html
Jase
mike
Göran Sandström
I don't know if you've read your .acc-mail, but there I sent you a letter
where I said what I'm going to say now too.
I, just like you, live in Umeå, and I've got a bunch of 4164 and 41256
laying around, and I've got soldering equipment. (And the knowledge how to
use it. I worked at a contract manufacturer of electronics with testing and
repair before I began my studies.)
I'm going to make an order from elfa soon too, so if you need som low
profile sockets...
So if you would like some help just let me know.
/Göran