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Posted By

Hypex
on 2017-08-02
23:47:28
 Possible 8501 replacement kit?

Hi guys. I came across this just ten minutes ago. Looks promising. An 8501 replacement using a 6510 on a PCB and a replacement ROM. The 8501 data port is not replicated exactly. Would be nice. But in the mean time this could be a goer.

http://hackjunk.com/2017/06/23/commodore-16-plus-4-8501-to-6510-cpu-conversion/#comment-153

Posted By

MMS
on 2017-08-03
16:55:26
 Re: Possible 8501 replacement kit?

Yeah, it is a fantastic find and development. As fas as I know, next to TED, this is the second most frequent defect (and ceratinly there are RAM, ROM PLA and PSU failures too).
Maybe 15-20% of the dead C16 and Plus/4 could be revived with this? For RAM and ROM we have solutions, for PLA there was a similar project, for PSU there is the c64 ones (for round PSU socket versions), and C16 can work with any unregulated standard external PSU.
So if it really works, only the Plus/4 with square connector, and the TED defect need some further solutions (for the later there is also a nice project too).

(OK I do not say, that desoldering the 8501 and solder a new socket is easy, at least not for me)

Posted By

Hypex
on 2017-08-07
10:40:24
 Re: Possible 8501 replacement kit?

The only concern is the missing port line that is worked around in custom ROM. That said, I wonder if an 8502 converter would be feasible? This has the 7 lines we need and there are sources of 8502 which may be cheaper. But the the odd placement of port bit 5 missing on the 8501 may disrupt this arrangement with bit 5 existing on the 8502 but missing bit 7. So that might be better than a 6510 but still not perfect.

Given that WDC looks like they still produce 6502 derived CPUs maybe it would be best to simply adapt one of those and put it on a compatible PCB. Since it would be a new source. Should be easier than trying to do an FPGA based 8501. Though WDC do provide HDL files.

I have found replacement PLAs here:
http://www.ebay.com.au/itm/C16-4-or-1551-PLA-Commodore-16-plus-4-chip-251641-02-251641-03-equivalent-/191782739112?hash=item2ca7245ca8:g:XJ0AAOSwHnFV03nj

http://www.ebay.com.au/itm/PLA-251641-02-for-Commodore-Plus-4-Commodore-16-and-Commodore-116/182691475391?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

If only one of these could be made up to replace the CPU. Like you said there is a WIP for the TED. The FPGATED.

I have a C16 here that is socketed on CPU but didn't know some Plus/4's has it soldered on board.

Posted By

gerliczer
on 2017-08-08
03:16:57
 Re: Possible 8501 replacement kit?

Cannibalizing working C=128s is a stupid idea. Working 8502s are best to keep as repair material for machines breaking in the future.

WDC 6502s are not compatible, because (AFAIK) they are 65C02s. The so called illegal instructions of the original 6500 derivatives are not present and those also lack the integrated I/O port.

No PLA replacement will ever have even a snowball's chance in hell to be turned into a CPU replacement.

Unfortunately, your best chance is FPGA implementations for [7|8]501 and [7|8]360. It's a pity that nobody is willing to make them.

Posted By

Hypex
on 2017-08-08
10:11:30
 Re: Possible 8501 replacement kit?

Well I don't mean to steal one from a C128. Even if it is stuck with an inferior 16 colour palette.

There are sources of 8502 CPUs and they tend to be cheaper than 8501s. I don't know if they are any more reliable. It would have been easier if C= used the same pin layout since the 8502 would be a logical follow up to the 8501. From what I can tell one pin side has the same lines but the other side differs, mostly being offset down one set of pins, from an extra pin on top section.

Given the port lines are read internally from location $01 I don't know if they can be set externally. Perhaps a bit of logic involved can detect a read /write on addresses $00/$01 and fill in the missing bits. But I don't know if the memory can be overridden.

It isn't only our machines that have this problem but the C64 as well. Which AFAIK was fairly popular. The CPU lasts longer but 6510 aren't around any more either. Be good if a run could be made of ASIC CPU's to satisfy both markets and any others. I am surprised an FPGA 6510 design isn't out by now that slots in place even if it would be seen as a "fake" CPU.

Given WDC used the 6502 design and bolted things onto it I'm surprised they didn't base it on the 6510 or 8502. It is the closest to being an ASIC 65xx CPU still available. Like above, I don't know if it could be bolted onto a PCB in a DIP 40 pin layout with logic to bring the extra port lines in. Perhaps easier to do if $00/$01 isn't mapped internally but can be set externally.

Another idea I have would be to have some kind of CPU on a cartridge. But I have read the 264 port isn't like the C64 one where it can have an external CPU. Still having a RAM cart would be good. It has been before. And there are cart PCBs available as seen on eBay. Bare and with EPROM.

Posted By

MMSZ
on 2017-08-09
12:29:19
 Re: Possible 8501 replacement kit?

When I told PLA replacement, I meant the PLA IC in the Plussy that can easily die too.
Certainly for a CPU replacement we need a CPU

PLA replacement project:
http://blog.tynemouthsoftware.co.uk/2015/11/commodore-64-pla-replacements.html
As far as I know the c64 uses exacly the same component.

As I know the top rootcauses of Plus/4 defect (with most frequent causes)
(just guessed figures based on diacussions, threads)
Maybe we can extend this list, how to prevent it, how to be sure it is the defect, and from where you can buy a new or used or alternative component

1) TED maybe 20-25%
Causes: joysticks with autofire, overheating

2) 8501 ~15-20%
Cause: overheating

3) Defective Roms ~20%
Cause overheating

4) defective PLA ~10%
Cause: ?

5) Defective RAMs
Cause: ?

6) with c16: defective PSU
Frequent
Cause: underpowered design, overheating

Posted By

siz
on 2017-08-09
15:34:11
 Re: Possible 8501 replacement kit?

To be on-topic: IEC-ATA also did a 6510 replacement for the 7501/8501 with a patched KERNAL for the serial bus port mapping: https://www.youtube.com/watch?v=dfWMJA69g1M
Unfortunately this one (obviously) does not support fast loaders but a 6502/6522 pair could do that. Or an FPGA implementation.

Posted By

Imperious
on 2017-08-10
08:31:28
 Re: Possible 8501 replacement kit?

What speed is the replacement 6510 running at? I thought the 8501 run at 1.76mhz mostly. I do realise it runs 1/2 that speed as well.

Posted By

siz
on 2017-08-10
10:41:25
 Re: Possible 8501 replacement kit?

It runs at the speed and behaves just like the original 7501/8501. The only difference is the port at $00/$01 which is different on the 6510 so the KERNAL had to be patched for it.

Posted By

Hypex
on 2017-08-10
11:05:30
 Re: Possible 8501 replacement kit?

I wonder if it would have helped if C= used the same layout as the 6510, since it has just one extra port line.

If you look at a 7501/8501 pin layout you will see I/O P5 missing. Which doesn't make sense. Except in putting the clock and data lines at the top in the same position as the C64.

Then in the follow up 8502 P5 is back but P7 is missing! We can't win! It's like C= really stuffed things up for us.

Perhaps if they mapped the serial port to TED or elsewhere it would have helped.

And just to make matters worse reboots like the WDC 6502 are based on the obsolete model and not the popular 6510 with an I/O port.

Perhaps FPGA would be best. Even if it isn't like a real CPU. Or a traditional one.

Posted By

RobertB
on 2017-08-15
20:16:55
 Re: Possible 8501 replacement kit?

Hypex wrote:

> I wonder if...

Those would be questions for CBM engineer Bil Herd at the c128.com forum.

Truly,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm

Posted By

Hypex
on 2017-08-17
00:28:57
 Re: Possible 8501 replacement kit?

Might be a good idea to ask that RobertB. Oh no, YAF. Yet Another Forum.

Since no FPGA 8501 looks like it exists yet I think I found the next best thing. An old project called 6502 to 8501. From 2001! A SpaceTED odyssey.

Here:
http://www.webalice.it/gratteri/65028501.html

It's been tested as working, as claimed here:
http://cbm-hackers.2304266.n4.nabble.com/6502-to-8501-board-IT-WORKS-td4063933.html

But I can see a problem with the design. The 8501 pinout is incorrect. It has P0 to P6 for the port lines. In the schematic it then uses P0 to P6 also. And on the 6522 implementing the parallel port it's wired incorrectly. The top bit is is not connected. The serial won't work despite the effort implementing the logic to do so.

Perhaps if this was corrected and a simpler redesign made if possible this could actually work.

Posted By

MMS
on 2017-08-18
08:28:04
 Re: Possible 8501 replacement kit?

As I see the biggest problem: there is not enough free space available within the Plus/4 to close the keyboard if you do not use the original IC.
So even with working converter board, it will be hard to used.

But from the original 8501R1 still some thousand pieces are available, though they are really not cheap.
https://www.aliexpress.com/store/product/MOS-8501R1/1200151_32280168665.html

You should search for 8501R1

Maybe we should add it to the non-existing "important shop" list. ;-D

Still >9900pcs available, that should be more than enough for our scene.
No claims visible, so they seems all in a working condition (more than 20pcs bought in this year, and only positive feedbacks visible)

I have 3 dead Plus/4s, I think 2 of them is most probably due to 8501.
Maybe would be good to make a Group purchase, and spread it locally (within EU).
I would be happy to help in this action, though recently the postage from Hungary to abroad became extreme expensive.

BTW, do you think, it would fit?
https://www.aliexpress.com/item-img/Wholesale-8pcs-set-22x8x5mm-Copper-Heatsink-Heat-Sink-for-DDR-VGA-RAM-Memory-IC-Chipset/32254500983.html?spm=2114.10010108.1000017.2.4b24ae2b7DgMS9


Posted By

Imperious
on 2017-08-18
08:08:18
 Re: Possible 8501 replacement kit?

To respond to Hypex's post. I actually tried making up that 6502-8501 board, and couldn't get any response from either the serial or cassette port. I think he removed it from his website due to it not working.
The other one from that Spanish website uses a WDC 65c02 and as that has a BE (bus enable) pin, there is no need to try to recreate that, which means using fewer chips.
Unfortunately He never gave any detailed information on what chips have been used, there is one I cannot figure out what it is. I think he has recreated the Gate-in line which has been ignored on the 6502-8501 schematic.
I have used a G65SC816, 6522, 2x 74HCT688, 74HC245, 74LS04, 74LS74

https://ibb.co/iPhGz5

Posted By

Hypex
on 2017-08-19
02:54:37
 Re: Possible 8501 replacement kit?

@MMS

Perhaps I should have posted the a C16 forum where the CPU board would fit?

I don't know if an inverted board would work but there isn't much space. My next suggestion. Stick the CPU in the cartridge slot.

A big thanks for a source of CPUs. It's funny as I started Googling 8502 numbers and came up with some of my own just yesterday. This was after finding a "MOS8501 SemiConductor" listed on eBay by Little Diode, from UK. Perhaps I should have ordered some. I sent a PM asking what it was and they said not available. I rephrased my question and finally got a don't know answer.

I Googled that "string" and something came up. I also tried 251536-01 and it comes up as well. An aircraft spare parts place even has them. LOL. The 8501R1 is a good start. But surely the 8501R4 is the superior choice? Not that it burns out any later.

One find:
https://www.hkinventory.com/p/d/8501.htm

Can't comment on the heat sink but I've been told this combo works. Arctic Alumina Thermal Adhesive and ICK40B sink.

I'd be in your group purchase but I'm outside the EU and in the AU. So it looks like I'm on my own. However, I recently found a Plus/4 owner in my Amiga group. So perhaps I could do a group purchase for the locals here. I've done it before with Amiga software.

:thumbs up:

Posted By

MMS
on 2017-08-19
09:06:54
 Re: Possible 8501 replacement kit?

@Hypex: welcome! I try to help you coming back to the real Plussy users! :-)

1) Although I supposed, Chine to AU would be cheaper and faster than to Hungary, I see no difference

2) Tha HK page is good, brings up two, one of them is German. (off: I can't help, but for the "Charlotte" company always the Iron Maiden classic come into my mind: "Charlott the h*rlott")
As I see, both needs an offer request by email, I feel much more comfortable to just put the CPU into the basket, pay and forget.
Anyhow, I ordered in the last years more than two dozens of different stuff via Aliexpress, and I've never had any bad experience
(OK, once the cheapo car roof antenna did not perform as well as expected, still looks good)

3) Heatsink: generally speaking copper is slightly better, then alu, but really not a big difference.
(would be nice to apply a heatpipe on 8501 )
On the other hand the grease quality may do a big difference in thermal transfer. In the past after an upgrade I used Thermaltake grease in my PC, but I was unhappy with the result, CPU was very frequently close to upper limit.
Then I bought an Austrian grease, Noctua (you may check their fans too, they are very very silent - for a price). Compared to Thermaltake, with Noctua my CPU showed 8°C less and my GPU 5°C less. Why I mention it? In Hungary the Noctua grease costs less than the half than the upper class Arctic greases, and performance-wise it seems to be very same result.
Thin application of grease is much better than the thick ones.
That's why the preapplied double sided heat transfer tapes frequently fail: they are typically just too thick for the task.
So there are some cheap and good looking heatsinks on the Ebay and Ali with self adhesive tapes (really easy to apply), but with grease they would perform much better. Some Raspberry PI owners reported zero impact on CPU temp when used such a heatsink (even copper ones)

4) Heatsink #2
I think the size of heatsink (bigger radiation surface may help) could be increased into the direction of the memory chips/ROMs


5) 8501R4:
Would be nice. But. I saw a guy offering even 60USD for an 8501R4 chip, but he could not get. I think with a heatsink the 8501R1 will also perform well.

This guy had one R4 in the past, and he offers TED too, maybe worth to ask him:
https://www.ebay.it/sch/commdorec65/m.html?item=181999387743&rt=nc&_trksid=p2047675.l2562

Anyhow, I would be surprised, if all the Aliexpress stock would be R1 only. I suppose it could be a kind of mixed batch.

6) Unfortunately the 8501 is soldered into the MB, not in socket.
So there is a high chance that I will kill the MB, when I try to remove the original IC and try to install a socket. (very bad soldering skills)


Posted By

Hypex
on 2017-08-19
11:45:57
 Re: Possible 8501 replacement kit?

@Imperious

If you look at the CPU pinout he has listed and the associated schematic here you will see it is has a mistake (or two) so I'm not surprised it didn't work. It looks like he based it on the 8502 conversion but didn't fix the port lines to match the 8501:

http://www.webalice.it/gratteri/65028501.gif

He has P0 to P6 listed but the 8501 doesn't have that in sequence, it just matches the 7 line count of the 8502 port. It has (the 8501), perhaps oddly, P0 to P4, with P5 missing, then P6 to P7. I suspect, without inner knowledge, that C=? wanted to match the serial layout of the C64 $DD00 port with DATA at P7 and CLK at P6.

Now, without being corrected, following that circuit, the DATA line is connected to the CLK input and the CLK is connected to NC P5 input! So every time it tries to use serial, DATA will be output on the CLK line and the CLK will be missing! LOL!

But I have to ask, did the core actually work? It sounds like it did. Just worse than the 6510 hack where serial can actually work.

I'm no electronic expert, having just dabbled in electronics when I was younger, and then slowly got into programming once I got my first computer, a C16. And your board is after my own heart, looks like my past projects. But having studied that circuit and related threads I can see the problem.

Without correcting the diagram, the on board fix should be simple. Reroute P6 and P5 going to the 6522 and move them up a line bit, so the P6 goes to PA7 and P5 to PA6. If you see what I mean. Relabeling the diagram would be more clearer. Hm. DPaint anyone?

Having read about how to turn a 6502 into a simple computer I've come to an understanding of address decoders and what those data lines are for on the 6502. Now it makes sense, in a nutshell, CPU sends out a request to access an address on the lines, then sucks in that location data byte or blows it out.

To simplify the design, since an access to location $00-$01 needs to be detected, what occurs to me is using an OR logic gate. A TI CD4048B CMOS Multifunction Expandable 8-Input Gate can be configured for this as cascade. The address MSB can go into one, output connected to another with the address LSB, then inverted and used as chip select on the 6522. So that when all A15-A1 lines are ORed together, the output will be zero, inverted into a 1 CS flag. A0 goes to the 6522 as usual. A15-A1 go to two IC chips and reduce the lines to just one. If that can work.

The 6522 also seems superfluous to me since it contains a lot of functions, basically being a CIA, but all we need is one parallel port and DDR. I read 6521 dual parallel port lacked something. I don't know what that was, but these days, I would think a WDC 65C02 and 65C21 combo should work.

A 65C816 also seems over the top, since we only need an 8-bit core, and the already extra opcodes of the 65C02 makes it worse, if they are accidentally are on purpose called upon.

If you still have your board, please try the above fix, and see if it works better.

Posted By

Imperious
on 2017-08-19
22:52:41
 Re: Possible 8501 replacement kit?

@Hypex

My apologies, as I should have mentioned I already tried putting the data ports in their correct place, still nothing worked. The point of using either a WDC 65C02 or the 65C816 is that it has a BE (AEC) line, and therefore the 74LS541's then are not needed to recreate that.
There is a possibility using HC and HCT logic chips are causing an issue due to the difference between logic levels as opposed to LS ic's.
I thing the guy on the Spanish forum had a better understanding of all this, he made a proper board up for it. I am an electronics tech, not an engineer, so my knowledge is not good enough for fully understanding this. I have some more pics and docs where I was trying to figure it out, I'll post what I have later and maybe someone can figure out the missing bits.

Posted By

Spektro
on 2017-08-20
02:56:16
 Re: Possible 8501 replacement kit?

Off topic:

Regarding the MMS's group purchase suggestion... Maybe the 264 scene should have some kind of a co-operative

Its members could invest some money to get the most wanted hardware projects materialized (CPU replacements, custom ROMs, memory expansions, SID cards, 3D-printed parts, and so on), or collect a stock of spare parts, or pay for the forum's domain name etc.

Posted By

MMS
on 2017-08-20
07:15:00
 Re: Possible 8501 replacement kit?

Off: Yeah, like a mini Kickstarter or what
Some of the parts became (or always was) really expensive (user port connectors, microcontrollers, special ICs), and it slows down or make impossible to realize working projects.
Sometimes the most talented HW people do not have enough free money to risk on projects with questionnable final result and limited user base. ( I am almost the opposite )

Posted By

Hypex
on 2017-08-21
01:18:47
 Re: Possible 8501 replacement kit?

@MMS

Yes thank you for the welcome. Suppose I should open a thread to introduce my self since I'm rather a stranger in these parts. And soon one day hope to to realise the teenage dream of having a Plus/4.

1.) Yes your likely right. Think I take advantage and get me some.

2.) (Haha. I hear what you mean. I do agree. I got a bit obsessed when I found it. I sent off some RFQs just for interest. For quantity of ten. I only got one email back so far, from another German site, giving me a price of about 35 euro a piece. For an 8360! I don't recall looking for a TED. :-?

3.) That's some good advice there. Is there a FAQ here you could add those tips?

Personally I've always wondered if an active cooler on any IC can increase risk of damage. A heat sink is passive. But for active cooling, you have two opposing forces, heat and cool, coming together on the IC. That would look to cause stress and fracture structural integrity. Perhaps it's fine.

4.) Should a fan be put into the Plus/4? It would match the fins outside the case.

5.) I thought an 8501R4 would be unheard of until I saw it listed. But would it be any better? Would C= have finally have fixed the manufacturing process to match the proven 6510?

6.) I read about this and it is a concern. I was given a Plus/4 years ago from an Amiga guy who used to go to my Amiga club. He couldn't find the PSU. I opened it up and the whole board was stripped. If it had a CPU I didn't see it. I have another one I've confirmed as broken from a broken black screen.

My soldering was better when my eyesight was but I wouldn't want to solder a computer board. Even an older one. Perhaps I should just have ago against the rarity of working boards. Still, a Plus/4 would be easier than doing SMD. I could do the C64 PSU "fix" but I rather like the trendy square connector. And C64 owners are still looking for reasonable plug-in replacement for their very popular computer.

That CPU in a cartridge is looking good against accidental DIY damage.

Posted By

RobertB
on 2017-08-21
02:33:32
 Re: Possible 8501 replacement kit?

Hypex wrote:

> 4.) Should a fan be put into the Plus/4?

Already have one in one of my Plus/4's.

Courtesy of Ray Carlsen's handiwork,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm

Posted By

Hypex
on 2017-08-21
12:46:25
 Re: Possible 8501 replacement kit?

@Imperious

Yes using a BE line should be good. I've also wondered about the TTL levels. And if they match. Perhaps some looking up for any difference between MOS 6510 and WDC 6522 parallel port will help. The circuit is proven, AFAIK, for 6510 and 8502, but it is old.

Another thing, what did you do with the missing P5? I've read TTL chips don't like floating pins so if it is left at NC it can cause instability. Did you tie it to ground to keep it at zero?

Did the Spanish forum guy post any diagrams or pictures? I look forward to seeing your extra pics and docs.

Posted By

Hypex
on 2017-08-21
12:48:50
 Re: Possible 8501 replacement kit?

@RobertB

Nice. Do you have pictures on your blog I may have missed?

Posted By

MMS
on 2017-08-21
19:38:56
 Re: Possible 8501 replacement kit?

Fan on a Plus/4 is like putting a fan on a Formula 1 car


Actually I think without heatsink the R4 should be more reliable, but with a proper heatsink?
I think after that the R1 should be as reliable as the R4, and the R4 should work till the next century.

(Heatpipe: it was just a joke. I designed few years ago a very slim computer, and heatpipe with the proper radiatior + very slim fan requires at least 40-60mm extra height for the cooling, and it is a bare minimum. or you need special horizontal design (like seen in some HP laptops) )
or just for an idea (this is an Australian company):
http://www.ebay.co.uk/itm/Heat-Sink-Pipe-Flat-Plate-1-2-20-100mm-Thermal-Aluminum-Cooling-LED-CPU-IC-GPU-/272635305655?hash=item3f7a549eb7:g:UAsAAOSwSypY9YjS

Posted By

filker
on 2017-08-22
05:53:06
 Re: Possible 8501 replacement kit?

A fan is good idea. Though I need a peltier or something similar for my Plus/4.

I cool its motherboard in the refrigrator first in order to be able to use it for ~5 minutes!.. As it warms up, the screen starts to fill up with @s, and crashes eventually.

Couldn't figure out the problem. CPU and TED works in another machine. Changed all RAM, sockets, capacitors, PLA, removed func. ROMs, Basic etc. inserted the diagnostic ROM instead... No luck yet. It likes sub zero temperatures.

Posted By

Hypex
on 2017-09-05
10:12:50
 Re: Possible 8501 replacement kit?

@MMS

That's funny. A Plus/4 might look even cooler with those fans spinning on the back! I got another email back on the RFQ. Almost 50 euro for an 8501R1. The 35 euro for the 8360R2 is looking good. So decided to take your lead and order from Ali. Put myself down for two. Will see how it goes. Now that Australian company flat pipe is just what I want on my Plus/4! Even without water or air cooling that should do it good. Looks and acts cool on the inside.

Posted By

RobertB
on 2017-08-24
15:40:42
 Re: Possible 8501 replacement kit?

Hypex wrote:

> Nice. Do you have pictures on your blog I may have missed?

No, I haven't posted any pictures of that. I'll try to remember and do it when I get back to California.

Writing from Portland, Oregon,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm

Posted By

MMS
on 2017-08-24
20:41:08
 Re: Possible 8501 replacement kit?

@filker
OFF I had a Apple G4 motherboard, when it got warm, one of the IC legs on the corner separated (due to torsion happened on IC due to heat) from the motherboard, as the soldering was broken (in fact it was the top1 faiilure mode of that laptop range, and seems to be a design issue).
When I pressed hard the top of that component (it was an inverter IC), then the laptop still worked.

From the sympthoms and the list of exchanged (and OK) parts does not look anything serious, but something that plays a role in the RAM refresh process and in warm condition do not make this. Missing this regulatar updates, the DRAMs start to loose their information after some time.
Unfortunately I am not a HW expert, but worth to check that part of circuitry, looking for a loose / cracked soldering on an IC or component leg.

The Mac case:
http://macintoshhowto.com/hardware/how-do-i-get-my-broken-g4-ibook-fixed.html
(hopefully somehow you can use it to find the failure mode and able to get back the Plus/4 from sub zero state)

Posted By

filker
on 2017-08-25
05:58:14
 Re: Possible 8501 replacement kit?

Thanks @MMS. Although I've checked all solder joints with a magnifying glass, it was a check in a cold state... I'll check that parts you've mentioned. It's certain that I miss something.
By the way, I bought a peltier today And burned it immediately! I was measuring the temperaures of the sides, and it popped in less than a minute. It really needs a big fan (which isn't a case for plus4), and didn't like the power I supplied from a 12V 7A gel battery.

Posted By

Imperious
on 2017-08-25
09:22:51
 Re: Possible 8501 replacement kit?

Well it appears I have less information on this than I thought. A lot of it was in my head, with respect to figuring out exactly what ics this Ferix guy used.
It looks like because He has used a WDC 65C02 with a BE line, he has left out the 74LS541's from the 6502-8501 schematic. I'm not sure whether he has used a 74LS682 and 74LS688 for the 6522 chip select, or used 2 74LS688's.
As I mentioned earlier it looks like he has tried to recreate the gate-in function, from what I can tell using a 74LS74 along with another logic chip I cannot identify. I can figure out he has used a 74LS00, 6522, 65C02, 74LS688x2 OR 74LS682, 74LS245, 75LS74.
I also can tell the Ferix board has just left P5 hanging there. He does show a photo of the c16 boot screen but no proof whatsoever that any of the external data ports are working.

http://www.filedropper.com/plus4-8501

Posted By

ken
on 2017-08-25
12:06:51
 Re: Possible 8501 replacement kit?

if you use the short Header connectors and flush mount machined inserts you can make a board that has more than enough clearance
I just tried a 28 pin adapter board in the socket and closed the cover , then looked into the rear user port and could fully see across the top of the eprom and it was not touching the keyboard
so a no soldering needed adapter can be made
ken.

Posted By

MMS
on 2017-08-27
14:58:57
 Re: Possible 8501 replacement kit?

@filker
in the factory I work we use 2 Peltier cooling element on each production line to keep the soldering paste at~25°C.
We have 12cm fans on them, and still te Peltiers die rather frequently, at least yearly we have to exchange each of them. If you do not cool is properly (on the hot side), it could overheat very fast.
(BTW this soldering paste cooling method developped ~12 years ago, and I can say it is rather advanced for it's age).

The heatpipe is nice as it could be a passive element, and the inside liquid's phase change itself transferring a lot of heat from the IC.
Usually they use a fan to cool down the gas, but I suppose, that from 8501 the linked thin (and long) heatpipe with a normal heatsink (outside the hot Plus/4) could be enough.

The only thing I do not know, how we could prove it is cool enough, and the cooling is efficient enough?
What is cool enough for the 8501?

Posted By

Hypex
on 2017-09-05
10:10:39
 Re: Possible 8501 replacement kit?

@Imperious

Wanted to thank you for the information you dug up there. I don't know how you identified any chips at all. I've examined the pictures and in the large JPG where the chips are visible it looks like someone has taken a small picture and blown it up digitally. It just goes into a square blur when I look at it in actual size.

I don't know where you found this Ferix guy from. I can't find any info on him on the net. Nothing C16 related shows up. A missing P5 shouldn't corrupt any data but I don't know if it would cause instability if there are loose TTL lines left floating.

What would be cool is if a working circuit could be put on a cartridge. Plug in a cartridge. CPU fixed! Or in the least a CPU tester. An external 6502 CPU being able to pull address lines and read memory would be good to test.

Posted By

MMS
on 2017-09-05
15:28:17
 Re: Possible 8501 replacement kit?

Partially OFF:
It is a little old article about spreading the proper quantity of thermal grease. (at the time of 200W Pentium 4s it was much more crucial, than nowadays with 35W i3s. Yikes!)
http://www.tomshardware.com/reviews/thermal-paste-heat-sink-heat-spreader,3600-5.html

Actually I do not suggest to use silver or aluminium based thermal paste.
Maybe Artc Silver only, as it is not a conductor.

Because if you overdone it, then it may flow down from the surface of the IC, and may cause short circiut (or just strange working) IC between the legs. PPl using them need to clean them off properly.
http://forums.whirlpool.net.au/archive/1730434

Anything above 8 W/(mK) is pretty good.
Artics are good, Thermal Grizzly is good (they even have thermal pad/strips with very good results, some is >10). I have no data about Noctua, but pretty good.
FujiPoly is one of the major industrial players, they have products (pads) have >17, that is really unusually high in this industry. But price is like hell.

and some suggestiosn from real users. Not all prefer the Noctua, but some do.
https://linustechtips.com/main/topic/319365-thermal-paste-nt-h1-vs-arctic-silver-5/

And finally a REAL test, hopefully not a sponsored one :-):
https://www.techpowerup.com/reviews/Noctua/NT-H1/4.html

Posted By

Hypex
on 2017-11-06
23:04:48
 Re: Possible 8501 replacement kit?

@MMS

I've taken your advice and ordered two samples for my use. I expect them to come next week. I've got my heatsinks ready to go. So thank you also for those guides including Whirlpool I'm quite familiar with. In addition I have one spare TED with the hope that one other TED is working. And hope that if one chip is fried already in testing that it doesn't take the new one with it. I've heard stories that one bad chip can kill another. Eeek!

Update:
Looks like I've done my money and lost two rare CPU chips. I's been almost two months since I ordered. No sign. I suspect I should have set up a PO box as delivery guys have been lazy in the past by leaving things in letter boxes that should have been signed for. Every time I tried to look up tracking there was no information. I had trouble signing in at one stage and lost the dispute window. So the system automatically assumes the order arrived without you confirming so. Not happy.

Posted By

Imperious
on 2017-11-07
05:54:32
 Re: Possible 8501 replacement kit?

Twice I tried ordering 8501's from Aliexpress, but it was a few years ago. There were sellers selling 5 for $38 or therabouts. Both times nothing ever arrived and I got my money back.

Recently I have noticed the Aliexpress link posted above is now dead, and nothing I have tried in the search bar has brought up 8501's. It is not easy fnding chips via Aliexpress search bar, unlike ebay.

I have a suspicion that Aliexpress have purged a lot of the smaller sellers as it appears harder to find various items than it was a year or even 6 months ago.

Posted By

MMS
on 2017-11-07
19:03:53
 Re: Possible 8501 replacement kit?

Really sorry to hear your troubles.
In the past I ordered several things from Aliexpress, and all arrived in a relatively short time, and without problem though I know these are different guys and companies behind the surface.
(controller, xbox chatpad, simple VR headset, arrows, midi connector, even xbox HDD,)

(PS I had similar experience with Dinodirect (after some OK buys), and then I stopped ordering from them. But never had similar experience with Aliexpress)

Posted By

Hypex
on 2017-11-25
01:19:04
 Re: Possible 8501 replacement kit?

Thanks for the chippy condolences. Compare to eBay CPU chips these were half the price so I could get two for one eBay price. When it was a month ongoing I new something was wrong. I'll just have to remain a soft C16/Plus4 user for now. With my broken Plus/$.



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