C128 and C64 OS

[Daniel]

Hi folks -

I've been really tempted to jump back into the CBM world after watching
a few demo vids of the c64 OS. Heard an interview on a podcast the other
night and... Well, impressed the guy got a wikipedia app running on the
OS. I actually reached out to the developer asking why he stood up a
propxy to scrape wikipedia vs pulling the data with existing API's. He
simply didn't know about it.

Anyway, tangents aside, I'm considering a purchase of a C128 and would
like to know if the C64 OS supports 80 column mode or does the user have
to switch to C64 mode to make it work?

RIght now, my only access to CBM is on a Mini i purchased at gamestop
some time ago but it's finicky about the sort of image it'll load from a
flash drive.

I bought an actual C64 off ebay a few years ago but haven't had a chance
to recap it. There's alot of residue and cleaning to do yet, and figure
out what else if wrong before I can plug it in.

Thanks.

Daniel

[phigan]

Post by Daniel
I bought an actual C64 off ebay a few years ago but haven't had a chance
to recap it. There's alot of residue and cleaning to do yet, and figure
out what else if wrong before I can plug it in.

Don't have the answer to your C64OS question, but there usually isn't a
reason to recap a C64. Unless of course you actually see the caps
looking bad. One big thing to worry about is the original power supply.
If possible, use a new one, or one of those little adapters that combine
two modern power supplies.

[Kalevi Kolttonen]

Post by phigan
If possible, use a new one,

This recommendation is simply too weak. You should
avoid the old power supply at all costs. If and when
it fails, it will usually take a lot of C64's chips
along with it. Do not play with fire!

br,
KK

[Robert Roland]

Post by Kalevi Kolttonen
You should
avoid the old power supply at all costs. If and when
it fails, it will usually take a lot of C64's chips
along with it.

Do you have any references for this? I mean, actual facts.

Have you ever seen an overvolting C64 PSU?

I suspect the issue is massively overhyped.

[Kalevi Kolttonen]

Post by Robert Roland

Post by Kalevi Kolttonen
You should
avoid the old power supply at all costs. If and when
it fails, it will usually take a lot of C64's chips
along with it.

Do you have any references for this? I mean, actual facts.
Have you ever seen an overvolting C64 PSU?
I suspect the issue is massively overhyped.

I am not sure.

Commodore Finland has several thousands of members
and I guess it is safe to say that everybody there
always recommends ditching the old power supplies.

I have just believed in those warnings.

br,
KK

[phigan]

Post by Robert Roland
Do you have any references for this? I mean, actual facts.
Have you ever seen an overvolting C64 PSU?

Just my own experience. And yeah, both of my breadbins have been
affected by bad PSUs. In one, the PLA got half-borked. In the other, one
of the sdram chips got messed up. Actually, the ram one might be a
coincidence of just ram gone bad along with the system's PSU gone bad.
The same thing happened to my Atari PSU that I've had for over 30 years
since NIB. Maybe it's this desert climate.

The PSUs from c64psu.com are worth it, imo.

[Adam Sampson]

Post by Robert Roland
Do you have any references for this? I mean, actual facts.
Have you ever seen an overvolting C64 PSU?

I found one earlier this year -- an Ismet-made wedge PSU that came with
a breadbox C64. The output was approaching 5.2V at the C64 end of the
cable under load.

Having dismantled it, the reason was that it uses a 7805 regulator with
a resistor divider to lift its ground reference pin a bit, and the
resistor values had drifted considerably. The PSU runs quite hot (not
helped by the heatsink and 7805 being buried in potting compound), so
this isn't terribly surprising after 40 years.

Initially I just replaced the resistors, which worked fine, but I later
found timperi's replacement PCB that uses a modern switching regulator:
https://github.com/timperi/c64-wedge-psu-pcb
I've built a couple of these now (using boards from an eBay seller) and
they run much cooler than the original.

Thanks,

[Anssi Saari]

Post by Adam Sampson

Post by Robert Roland
Do you have any references for this? I mean, actual facts.
Have you ever seen an overvolting C64 PSU?

I found one earlier this year -- an Ismet-made wedge PSU that came with
a breadbox C64. The output was approaching 5.2V at the C64 end of the
cable under load.

Does that actually matter though, is 5.2V high enough to cause damage to
anything?

[Robert Roland]

On Tue, 20 Aug 2024 12:27:19 +0300, Anssi Saari

Post by Anssi Saari
Does that actually matter though, is 5.2V high enough to cause damage to
anything?

It is still within the tolerance of both TTL chips and the DRAM chips,
so no damage should occur. Yet.

However: The voltage will not have been this high when the PSU was
new. The fact that it is this high now means that something has
changed. If it has changed, it may continue changing, and one day the
limit is reached.

[Robert Roland]

Post by Adam Sampson
Having dismantled it, the reason was that it uses a 7805 regulator with
a resistor divider to lift its ground reference pin a bit, and the
resistor values had drifted considerably.

I have been thinking about various failure modes that could possibly
cause an overvoltage condition. This is the only one I have been able
to think up. Thank you for confirming.

Not all versions use these voltage boosting resistors, though, so the
myth that all of them will fail, is still on thin ice as far as I am
concerned.

[Daniel]

Post by phigan

Post by Daniel
I bought an actual C64 off ebay a few years ago but haven't had a chance
to recap it. There's alot of residue and cleaning to do yet, and figure
out what else if wrong before I can plug it in.

Don't have the answer to your C64OS question, but there usually isn't a
reason to recap a C64. Unless of course you actually see the caps
looking bad. One big thing to worry about is the original power supply.
If possible, use a new one, or one of those little adapters that combine
two modern power supplies.

The breadbin case is in great shape and the keyboard is complete. I had my
neighbor test the PSU when I got it and he said it was junk.

After opening the case, it was obvious that a good number of the
capacitors were misshaped, leaky, and left quite a bit of residue and some
rusty looking traces.. Some of the resistors flaked off too, so I
ordered a few of each type from the BOM online. Didn't cost more than a
few dollars.

It's going to take a ton of work to restore it, then I need to get a
test rig to see if any of the chips need replacing, if any. I don't know
if the previous owner plugged in the power supply it came in but I knew
well enough not to. I really hope the chips are in good shape.

In the meantime, I have a C64 mini that I use for daily driver.

I have a growing interest in getting a C128.

Daniel

[phigan]

Post by Daniel
ordered a few of each type from the BOM online. Didn't cost more than a
few dollars.

Ah, ok. Good luck with this.

Post by Daniel
It's going to take a ton of work to restore it, then I need to get a
test rig to see if any of the chips need replacing, if any. I don't know

Are there any C= users groups near you that might have someone with a
test harness? I always want to get one myself, but I just can't bring
myself to spend the money on it :).

Post by Daniel
I have a growing interest in getting a C128.

Yeah, I had always wanted a 128 since I was kid, so I finally bought one
from Europe a couple years ago. Definitely wanted PAL so I could watch
all the demos!

[Divarin]

I can't speak about C64 OS as I haven't tried it but with your C64 I would
not recommed recapping unless you know for a fact that there are bad caps on
it.

I'm not a proponent of replacing caps "just in case", caps aren't the
ticking timebombs that CMOS batteries are unless you can see it leaking and
spreading down the traces of the board.

Also modern caps are not necessarily better than the ones already in your
C64. Yes they can go bad and you may end up having to replace one or two at
some point but they're not likely to destroy your C64, more likely it will
just start acting a little flakey.

However I have multiple commodore 8 bit machines all with original caps and
never had any capacitor problems in them. In-fact just this week I was
working on an early VIC-20 and suspected a cap, desoldered it and tested it
and it had a better capacitance and resistance rating than the modern
replacement I was considering putting in its place so I ended up just
putting the original cap back in. My issue turned out to be just an
improper power supply.

I think the whole "recap everything" idea stems from the late 90's PCs due
to the capacitor plague but the C64 and C128 did not use those capacitors.

What is likely to destroy it is the original power supply as those tend to
fail in such as way as to start pumping 12 volts (or more) on the 5 volt
line. I would either build or buy a modern power supply or at the very
least invest in a "c64 saver" which is basically an in-line fuse to protect
your c64 when the power supply dies.

If you are considering also getting a C128 then make sure to get a power
supply with enough amperage for the C128 as well. There are adapters you
can get to use your c64 power supply on the 128 but the 128 requires a
higher amp rating than the 64 does.

Post by Daniel
Hi folks -
I've been really tempted to jump back into the CBM world after watching
a few demo vids of the c64 OS. Heard an interview on a podcast the other
night and... Well, impressed the guy got a wikipedia app running on the
OS. I actually reached out to the developer asking why he stood up a
propxy to scrape wikipedia vs pulling the data with existing API's. He
simply didn't know about it.
Anyway, tangents aside, I'm considering a purchase of a C128 and would
like to know if the C64 OS supports 80 column mode or does the user have
to switch to C64 mode to make it work?
RIght now, my only access to CBM is on a Mini i purchased at gamestop
some time ago but it's finicky about the sort of image it'll load from a
flash drive.
I bought an actual C64 off ebay a few years ago but haven't had a chance
to recap it. There's alot of residue and cleaning to do yet, and figure
out what else if wrong before I can plug it in.
Thanks.
Daniel