| Posted By
candle
on 2019-04-04
18:07:57
|  what are the odds of massive failure of plus 4
Hi All,
I've just had a chance to get "sold as is, not tested" unit off ebay for fairly good price, and i was happy even it can be it will not work, as i'm a hardware designer myself and wanted to have some fun with troubleshooting and possible repair
after a bit of a wait for shipment i found that unit is dead - charlie good i thought hoping for easy repair
well.. what was good in that plus 4 was TED - so this is a win, but what failed puzzels me
unit was in fair cosmetic shape, but obviously there was no internal shielding - even c16 has cardboard one or proper metal shield, and on the pictures i've seen around this site there was some evidence of some kind of shielding, at least to some extent, so my guess is that is was open in one point of time
after borrowing known good c16 i've checked what was simpliest to do
cpu - dead
pla - seems to be working
basic, kernal - good
ted - good
ok, this was promosing - cpu shouldn't be that hard to find, right?
after replacing cpu with the one from c16 still no go - but one of memory chips run hot
quick look on data line reviewed that it is actually damaged, so i've replaced it
still dead - quick look over ACIA crystal pins revealed distorted oscillations that should a sinusoid, but was not
i've figured it is not needed for basic operation so i've pulled it out
this time plus 4 come to life - screen was almost ok, but at least i had blinking cursor and a welcome message
keyboard was not responding and there were some random chars in few places over the screen
after what i've read, i've suspected MOS 6529 chip gone bad, as this was responsible for keyboard - unfortunatly it was not socketed, so after socketing it i found that it is not the case
then i've put my scope over PLA to see if that chip is even getting selected for reads - it was not...
after replacing PLA (another borrow from C16) plus 4 was operational
it seems odd for me that it had almost all socketed chips bad, but on the other hand i know very little about commodore, and absolutly i don't know a thing about TED based computers, but whit experience i've gathered working as a designer, and repair tech i know that at first, failures are simple, not that major and complicated as it was here
what is your experience?
also, are there common upgrades i could make to this unit that would make it more usable 2019?
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Posted By
George
on 2019-04-04
19:23:48
 | Re: what are the odds of massive failure of plus 4
Hi candle,
welcome to this site.
The cause of all the failures seem to be the original commodore power-supply, which get worse the older they get. The output is not stable and the voltage goes up over time, which fries the chips. Mine starts to smell burned , so i have to replace it with a modern one. Many put heatsinks on the chips, but i beleive the first to do is getting a modern power-supply and then put the sinks on.
I do not use mine often, do my stuff on emulators and then test them on a real machine.
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Posted By
Luca
on 2019-04-05
02:00:10
 | Re: what are the odds of massive failure of plus 4
candle, both real facts and legends mix up in theTED/CPU failure's affair about the Commodore 264 series machine. George has just picked up one good point about, and my 2ç are: the bad habits of the users themselves, especially about managing the joystick connections (mostly while machine's on) and the usage of low quality joystick's converter cables, because there's no shield between TED and joysticks' attach.
For a deeper, longer, quite complete discussion around the subject, I direct your reading toward this thread, where all the "parties" speak, plus Bil Herd, the man behind the machine.
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Posted By
candle
on 2019-04-05
08:22:02
| Re: what are the odds of massive failure of plus 4
Hi!
Thank you for your input
I've stumbled on this thread yesterday, but from my perspective, heatsinking chips that run fine for 30+ years is not about science, but religion, and this is certainly not my area of expertise
other than this - yes - my first computer was atari 65xe, and thus problems known from commodore world - ie frying computer because of neglect use of joystick port
atari has well protected input ports, where commodore in general has not, thus is prone to statics discharge and other mishaps - but i guess this is down to the pennies that were shaved off the design
anyways, is there any upgrades i should get/make to get this machine to be more usable, or stock is enough and expcept for some kind of disk drive (iec, or something more like pi1541 due to fastloader support or lack of) is needed?
sid chip seems to be quite common upgrade - don't know the base address though, and i don't know how it would sound with double speed cpu clocking - or there is another method of providing phi2 signal?
it is fairly easy to expand memory to 256k - just wonder if this is used by any software
this is just my atari thinking - stock is pretty useless, one needs 320k of ram at least, with 1088kb being common, solid state drive and some kind of graphics card installed - either provided basics, but with dvi/hdmi output, or extended capabilities (ie vbxe)
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Posted By
George
on 2019-04-05
08:58:39
| Re: what are the odds of massive failure of plus 4
Hi candle,
i can only tell from what i have experienced here and from the things i do.
We usually work with stock machines. The only thing i bought was a sd2iec for transfering files. Many like work to with the original disk drives.
Since the 264 sereis has 16k (C16, C116) and 64K (plus/4) machines, we usually try to fit the demos into the 16K machines too, except someone wants to dedicate his work only to 64K for one reason or another.
Greetings
George
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Posted By
Lavina
on 2019-04-05
13:28:51
 | Re: what are the odds of massive failure of plus 4
Strange about JOY port.
I remember having all kinds of rubbish joysticks attached, detached on the fly many-many times, as well as inserting one of the joys which has lost the small plastic part from the middle of the connector to the tape port and typing load + RETURN.  ))
I cannot describe the screen the poor machine produced, but after a soft reset all went back to normal :D
My PSU is also veeeery old and used, still no problems whatsoever. I did not really know anyone at my hometown back then who had any problems with their Plus4 hardware.
Cheers.
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Posted By
MMS
on 2019-04-06
05:02:10
 | Re: what are the odds of massive failure of plus 4
Maybe a little hypothetic/OFF point
The whole story reminds me to our ESD experience at Philips.
When we started to produce DVD players and CD recorders, the office persons did not care about ESD.
I mean, there were some precautions (the intrernal wrapfoils were ESD free or condustor, including the boxes, we had humidity control, etc), but the personal protection (coats, ESD bracelets, etc) was used exclusively by the repairmen and assembly persons on production lines. And there was no tight control, if properly used. Especially low educated workers tend break the rules and cheat us.
So after 1-2 years the laser diodes of the CD and DVD drives started to weaken and die on the market, so we got a very detailed training how ESD works, so all the engineer and management staff had to wear all the ESD protection TOGETHER. It is not required to even touch the PCB to kill it, if you are charged enough in your pullover, it is enough to get close enough to a PCB on a desk to kill it. Not immediately, it is a slow agony for the ICs. The more you use, the earlier it shows the effect. It may take years to show the results...
The ESD taken very seriously, even an engiunner could get a warning going next to the production line without proper protection (ESD coat, etc). Then this kind on died ICs and laser diodes disappeared on the market, and our Field Call Rate dropped by almost 2%. This is a lot, if you translate it into warranty cost.
I agree, that the overcurrent protection-free TED did not help too much, and the 8501 us rather hot at 2.2MHz. On the other hand (based on my personal experience) I am not 100% confident, that all the ESD rules are ALWAYS kept at the different production lines (these machines were produced in Germany, UK, but also Far-East AFAIK). My experinece is from the early 2000. So you may imagine how much they may know at the mid 80s (not at the IC factories, but at final assembly lines)
It may happen, that these ICs were also sensitive to ESD, but much more resistant than a laser diode. So it may take 5-10 years of operation to die... Then we cannot do to much, just to swap them to modern equivalent ones.
To prove it, it would be interesting to see the defect ratio of the different production factories, and WHERE the currently working ones made. Please do not forget, that C= planned working machines only with 2-3 years lifetime, and C= always tried to save pennies everywhere. ESD protection costs a LOT, so if they chose a cheap location, probably there could be "issues" or loose control on that point.
But it is just a hypothesis.
About upgrades:
256KB extension diagram seems not so complex, but it requires internal wiring and soldering AFAIK. I am not brave enough to endanger the "life" of my only living Plus/4 :-)
Actually there is a not documented pin on the Expansion port say N/C, while on an early diagram is says Ram Enable. I put this question to Bil on FB, if the Plus/4 external RAM expansion was really planed or not, but got no answer.
Till the external RAM expansion is not possible, for me it is a NoGo solution. If an external one could be developed, I am in to buy one.
There are some SWs using this 256KB RAM expansion (Solder/Csory/Hannes), but I think they could be more wide-spread if it could work as an external (online buyable) unit, worth to mention, that I would recommend external (eg USB based) 5V Power source for that to do not overstress these old circuits.
I highly recommend SD-1541/II, it is a fantastic IEC unit with very high compatibility and a nice intuitive UI and control. It is developed in Hungary,and can be ordered from here. I saw several ones at Arok 2018, and I am not aware of any SW cannot be run from that, even the latest C64 demos ran perfectly.
http://retroemu.hu/sd1541-ii.php?lang=en
There was no aim to develop a new GFX card, because our TED chip is the best! If I put away the jokes, certainly HW sprites and chunky GFX modes would be great, but you know SID cards are also rather expensive, I am not sure, who would invest so much in such a small community?
There is one more challenge: there is no chance to produce expansion port expander/splitter, because of the very strange pin distance we have, you cannot buy that connector from anywhere. So you have an 1551, a SID Card, and maybe a GFX card, or a memory expansion, and you should choose, which one you prefer, as you cannot them all together.
Solder had a solution for that, he developed the external cards with C64 connector, and he developed an expansion port splitter with C64 type of socket (taking out the N/C pins) and it was easy to buy.
Two years ago I personally saw a highly upgraded Atari at Ha'vangarda in Poland, if had internal SD, RAM upgrade and an extreme GFX card (had original pokey sound card, eh :-) )
(Maybe it was owned by Hellboy? I am not sure). It was a very nice experience, but I think it is not the way this scene will do.
If you check, even less and less new release with "only SID music", or the original TED's SID FRQ emulation is also used. (because our machine is so capable :-) )
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Posted By
candle
on 2019-04-06
19:17:19
| Re: what are the odds of massive failure of plus 4
even so, one should stop using the machine when any of this components fails - any of these failures renders whole thing unoperational - either with black screen, or no keyboard as input device at all, thus i would exclude creeping esd failure emerging after the years - at least for this unit
as for RAM expansion - is there any banking scheme that is recognised by the community as "standard"?
i've developed many expansions for atari 8 bit line in the past, and still do it whenever i'll find the time - some of those became de facto standard of doing things on this computer
as for the pich of the cartridge connector - i think it is shared between commodore 264 series, atari st/ste/mega and falcon computers - just wonder if the pin count matches - don't have plus4 right here, but other machines i've mentioned have certainly the same pich i saw on plus4
sid chip becomes prohibitory expensive, and chinese suppliers were known to counterfit these chips for some time - current situation is not going to get better i think
there is swin sid project, but the output produces is.. questionable - for casual gamer is okay i guess, but for sid evangelists even real one could be from wrong batch/technologic process (old sid vs new one)
i wonder if saa1099 would be acceptable - they are plenty, dirt cheap and have 6 voices in small, dip20 package
there are some implementatons in fpga, or even small and relativly cheap cpld chips aswell (ie mach xo2 familly from lattice semiconductors)
most custom chips in c16/plus4 are soceted, thus, if external solution is hard to accomplish, and internal ones so far required soldering skills, then i wonder if solution that would be internal, but act as drop in replacement or add-on for internal chip could be a way to go?
my current course of action is get my plus4 going again - thus i must develop:
- cpld based PLA replacement (yes, i saw EPROM based one - i thought it should be possible, since PLA had only 8 output pins, but it might be tight to fit it there due to low profile of the unit
- cpu replacement - this time i'll take a path already explored by others - plain 6502 plus external logic to make for that missing port and bus separation circuit - or/and - 8500 based solution with justs the missing bits implemented outside the chip - it should require less logic to implement it if data is still presented on the bus
- GAL based mos 6529 replacement - just in case i would need one
anyways these are the goals for me for the next few weeks
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Posted By
MMS
on 2019-04-08
18:37:26
| Re: what are the odds of massive failure of plus 4
Atari ST connector vs plus/4
I already checked it in the past as I also realized the same pitch.
Atari used the same pitch for the ROM cartridge port, and because it was limited in size (64k?) it was hardly used. Certainly it had much less pins-
Interesting, that ST was Jack Tramiels first computer after plus/4, and seems the only computer in history used the same non-standard pitch.
Plus/4 has much more pins.
In fact i would have troubles to find so many pins on any cables, even including SCSI cables. (I was considering a converter cable for external expansion unit, to use a more standard and available connector.
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Posted By
candle
on 2019-04-08
12:25:09
| Re: what are the odds of massive failure of plus 4
as for edge connector - there is MEC2-DV Series - 2.00 mm Mini Edge Card Connector by SAMTEC
unfortunatly, there is limited sizes, and the only possibility is to use part of larger one as a cartridge backplane of some kind
unfortunatly, this is smt part, so it might not be durable enough for daily use
at least not without some kind of enclosure around it providing some kind of mechanical stabilisation
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Posted By
candle
on 2019-04-08
20:24:51
| Re: what are the odds of massive failure of plus 4
i've just finnished pcb for 8500 adapter, including SRAM based memory expansion that should be compatible with Hannes/CSORY 256k - i've uploaded picture over my site, but it seems to be down? although i don't know why since ftp side of things works :/
would post it here, but don't know how - can't find a way to register too - seems this is closed community, and the only way i could post is as guest
anyways, http://spiflash.org/c264/mos8500-to-8501.png
whether it work, or how good i'll know in few days - depending of so called "real life" duties 
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Posted By
MMS
on 2019-04-11
16:47:38
| Re: what are the odds of massive failure of plus 4
Unfortunately the link does not work.
If it is not too complex, I may repeat it, though first I have to learn how to solder (OK, properly...)
This mod could solve two things at the same time: dead 8501, and the hard to realize 256K upgrades.
(comment: the SAA sound IC you referred is used in the SAM Coupe also in the Turbosound for ZX Spectrum.
Even Gameblaster and Soundblaster 1.5, although in the later noone used it (they preferred the Yamaha, but it was much more complex to program)
SAA seems to be a rather decent IC, especially seeing, how easy to swith to digital (eg. MOD) playback.
Certainly much cheaper than SID.
Sound is kind of something between TED and a chopped down SID (sawtooth, noise and square without filters), and really enjoyable, and a lot of digital music seen in demos.
https://velesoft.speccy.cz/saa1099-cz.htm
Would be a nice expansion like the Sound Expander for C64
And certainly the price of an SAA1099 is 1.5 - 2.0 €, that is nothing, even if stereo dual use planned.
Well, nice collecton of game mui th dual SAA1099 :-) Really like a TED on steroids.
https://www.youtube.com/watch?v=ZwgZzuFXzLc
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Posted By
MCes
on 2019-04-11
02:42:06
 | Re: what are the odds of massive failure of plus 4
replace 8501 with a 8500 (or 6510) has some heavy hardware limits....
https://plus4world.powweb.com/forum/37903
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Posted By
candle
on 2019-04-11
08:24:56
| Re: what are the odds of massive failure of plus 4
i know these limits, thus i've added externally missing bits in that io port using cpld - write is simple to implement, don't know how it will turn out with reads - if these bits are missing from mask and will be floating then we're good, if they are implemented, just unconnected outside - i'll have to move to another cpu
i've already made 6502C adapter (Sally, Atari part no CO14806) - they are plenty on ebay, and price is reasonable
using this as a donor cpu seems to be logical, because all bus separation logic is already there (Sally's HALT line does more or less the same thing as AEC of 8501/8500) and the only thing missing is internal CPU port
if still no go, then i have mos 6502 pulled out of internal C128D disk drive for futher experiments
anyways, i'll get there, just a matter of time
as for ram expansion - it only requires one single signal from TED - CAS, other than that, it is self-contained and just plugs into cpu socket
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Posted By
unclouded
on 2019-04-13
21:15:23
| Re: what are the odds of massive failure of plus 4
One thing I would love (apologies if it exists already) is a cartridge that would allow me to blast code in to the C16's RAM so I could cross-compile and then upload the binary image to the C16 and then reset it, all under the control of the PDS
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Posted By
MMS
on 2019-04-14
11:56:22
| Re: what are the odds of massive failure of plus 4
Little OFF:
Let me ask, do you think if I add it to a C16, the 256K SRAM module could be seen by the computer also as normal 64K RAM?
It would be a great way to prevent those trace cutting for the 64K RAM expansion
Just buying a defective C16 (I prefer due to my childhood experience), swap the defective 8501 with this one, and may add PLA replacement having working and RAM expanded in 70% of the cases... (PSU could be used from my Spectrum).
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Posted By
unclouded
on 2019-04-14
22:52:02
| Re: what are the odds of massive failure of plus 4
Hi @MMS, I did the [Idörègèsz 64K upgrade](https://idoregesz.hu/product/commodore-c16-internal-ram-upgrade-to-64k/), which didn't involve any trace cutting, which I also was averse to.
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Posted By
candle
on 2019-04-15
08:07:34
| Re: what are the odds of massive failure of plus 4
i would say yes for c16 expansion in that way you've described
we will see in couple of days if i don't get swamped by so called "real life" tasks
how can i check memory expansion compatibility? is there any utility for this kind of upgrades?
external expansion in form of cartridge is also possible, but i know too little in terms of external devices existing using that port and if it would be legit to block it doing just this
i thought it would be nice if i would make 1551 compatible drive using sd cards as a medium, but then found that there are some severe compatibility issues using 1551 in general
it seems like commodore in general is stuck in terms of modern storage devices
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Posted By
MMS
on 2019-04-15
15:06:45
| Re: what are the odds of massive failure of plus 4
@unclouded. You are right! I always forget that piece of HW. My bad.
In fact currently I does not own a C16, because few years back it was much easier to get a working plus/4 than to organise 64K RAM upgrade.
And a C116 is way too expensive...
(that RAM expansion still it does not cure bad 8501, and I have 3 defective Plus/4s).
@candle Thank you for the info! I am really curious about the outcome. You have a customer then :-)
Actually any bigger 64K game would do the job to check 64K utilization, Mercenary is one of the bigger ones, and the recent games (Pet Rescue) left only few bytes left from 64K.
For the 256K there are some disc tools and intro demo from Solder of Synergy for Hannes 256K expansion.
http://plus4world.powweb.com/effects/256K_Support
Real life is a big destroyer of hobby activities, 100% proven! :-)
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Posted By
candle
on 2019-06-10
04:33:20
| Re: what are the odds of massive failure of plus 4
seems that spam filter triggers whenever i want to put a valid link to the pictures
sorry for this
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Posted By
Csabo
on 2019-06-10
08:05:29
| Re: what are the odds of massive failure of plus 4
You can either post the links without the HTTP part (so it's harmless text) or post a maximum of two links per post. The spam filter is set to detect a post as spam if it has 3 outbound links in it, it's extremely common in actual spam.
For image uploads, you could look into something like imgur. It's free, you can upload unlimited pictures, and you will end up with a single link that points to your album.
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Posted By
MCes
on 2019-06-10
10:11:39
| Re: what are the odds of massive failure of plus 4
64k ram expansion can NOT be performed into a cartridge because it will conflict with internal 16k ram bank that is mirrored 4 times (the 2 MSB address lines is not used for decodify the RAM address bank).
Unluckily for the same reason if the SRAM on "6502 PLUS 4" is on "8501 buffer side" it will conflict always with original 16k memory, if the SRAM is on "6502 buffer side" it will be not reachable by TED as grafical memory....(the TED will get bytes from a mirrored areas of internal 16k)
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Posted By
MCes
on 2019-06-10
10:22:15
| Re: what are the odds of massive failure of plus 4
@candle "anyways it works using generic 6502 bought from china"
beware by 6502 from chinese market: they can be EVERYTHING!
I modified the VIC 20 kernal to make cpu test at startup (CPU was detected in 3 cases by result of critical/illegal opcode: 6502/65C02/R65C02) and I found a lot of surprises..... some 6502 was 65C02! (N-MOS or C-MOS can be tetected also by Icc, by Voh, and on your table.... by a multimeter!)
http://sleepingelephant.com/ipw-web/bulletin/bb/viewtopic.php?f=3&t=9225&p=103241&hilit=27hc641#p103241
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Posted By
candle
on 2019-06-10
11:01:22
| Re: what are the odds of massive failure of plus 4
it's all true - it can be everything, so i've put there pulled out cpu from atari1050 disk drive with turbo board using generic 6502 back from '80
and for china chips - i've ordered them from 2 sellers, one are "rockwell, mexico" marked and on the bottom side there is "hong kong" stamp, the others are "MOS" - but both have their markings done with laser engraver - how suitable for the era they were manufactured in? and for what purpose they did even bother to do such thing? 6502 is 6502, i do not care if it would be syntek, mos, rockwell, umc, or whoever elses as long as it works and is in fact 6502
65c02 won't execute illegals, and can't be KIL'ed so this is an easy check
anyways, hardware works, regardless of cpu one puts in
todo: get some demos/games that would utilise 256k and get that part working
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Posted By
MCes
on 2019-06-10
13:22:37
| Re: what are the odds of massive failure of plus 4
unfortunately I had to constatate that also the speed label is fake on chinese 6502: when I had to use them for 2MHz operation I had to test the bus time response to identify wich was 1Mhz and which not...
the C16 PLUS/4 need a 2MHz CPU with "Tads" shorther than normal
(the 8501 timings are referred at the INPUT clock, the 6502 timings are referred at the OUTPUT clock, so the deley time from input to output clk have to be summed at timings declared on 6502 datas...)
I'm afraid that you will to select the CPUs from an chinese stock.... I have no information about how many CPU will be out of spec, but it can't be zero....
this is what i think
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Posted By
candle
on 2019-06-15
09:56:52
| Re: what are the odds of massive failure of plus 4
current status: all cpu i own works perfectly with this board in full voltage limits (5V +-20%) meaning board is not sensitive to timing variations
SRAM part also works - it was not as easy as i thought altough i had some results immediatly
making it solid and without issues with TED accessing the bus was another few hours of work
anyways, now i'm puzzled
what is banking scheme of ram expansion around here?
Atari is pretty simple - a 16k window starting at 0x4000 - might have separate cpu and antic access and thats all
here we have almost all ram replaced by a bank, starting from 0x1000 or 0x4000 - okay, can do that, no worries, and then i read somewhere banks have 16k each - this doesn't work with the hardware schematics i've seen, thus my question
is there any ram test program i could use to check how much ram is availabe for cpu, test it or something?
my 1571 drive seems to be able just to read disks, and writes are corrupted, and my 1541 drive is still 200km away, leaving me limited to the software that will work from sd2iec solutions i've build in a hurry few days ago
best for me would be to see this banking scheme from programmers point of view
edit: just to note: power consumption went down by 150mA just by removing old, now unused ram chips
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Posted By
Midge_the_Mouse
on 2019-06-15
10:00:36
| Re: what are the odds of massive failure of plus 4
I dunno if it's true using any kind of joystick or joy-pad with auto fire is asking for trouble too
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Posted By
candle
on 2019-06-15
10:03:33
| Re: what are the odds of massive failure of plus 4
the way TED handles joystick ports is prone to troubles and misshaps rendering TED useless or partially broken
a simple logic buffer per joystick plus some common sense ESD protection on port will do though
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Posted By
Midge_the_Mouse
on 2019-06-16
01:02:28
| Re: what are the odds of massive failure of plus 4
So candle this logic buffer and ESD protection is their a mod for this or any more information how it's done
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Posted By
MCes
on 2019-06-16
05:56:54
| Re: what are the odds of massive failure of plus 4
candle wrote"edit: just to note: power consumption went down by 150mA just by removing old, now unused ram chips"
I think that it has to be clear: the presence of SRAM into mod-board is INCOMPATIBLE with the physical presence of the original RAM chips on motherboard.
It means that the mod-board CAN'T BE USED simply swapping it with a (faulty) CPU, but it need to desolder the 2 RAM chips: who can't/won't/is not able to do it couldn't use this specific mod.
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Posted By
candle
on 2019-06-16
08:54:25
| Re: what are the odds of massive failure of plus 4
i don't know what is your point - am i a threat for your doings or what?
and yes, since there is no cas inhibit line in plus 4 or c16 you can only make a clean ram upgrade that doesn't require pulling old chips out, or cutting CAS line to the DRAM - not if you doing this with CPU socket anyways
for this purpose one has to make an adapter board for TED, as codingkoala c16 mod is doing
and if one uses SRAM chips or DRAM chips - who cares, you can use DDR4 chips if you're willing to, won't be easy, will be insanly stupid and complicated, but certainly it is doable
this board requires either that old ram chips will be removed (and then you can use expanded memory) or left in place and you're limited to whatever ram size you originaly had
in other news...
macro assembler detects it has expanded ram, but hangs on ram size testing - or so it seems, but hey - i'll get there
[edit]
well.. it's hard to get macro assembler by csory to detect hannes mode extended memory
csory mode will have to wait for next revision of this pcb - have to add support for 16k banks, hopefully it will fit inside cpld
but on the other hard - future world trackmo part works, but still would rather use some kind of memory test program
detection inside future world is quite bizzare - it detects sid chip i don't have in 8/10 cases, and reports over 2mbytes of user rom - most probably because i've pulled off 2 chips with plus/4 software - i don't feel like using spreadsheet on plus4 any time soon
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Posted By
Midge_the_Mouse
on 2019-06-16
10:26:24
| Re: what are the odds of massive failure of plus 4
At Candle about the logic buffer and ESD protection is this a mod or do you have any more information please?
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Posted By
candle
on 2019-06-16
10:58:33
| Re: what are the odds of massive failure of plus 4
https://blog.tindie.com/2019/01/commodore-264-joystick-adapter/
a bit bulky, but seems to be avaliable at least
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Posted By
Midge_the_Mouse
on 2019-06-16
11:19:17
| Re: what are the odds of massive failure of plus 4
Thank's for your response very helpful indeed
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Posted By
MCes
on 2019-06-16
15:38:59
| Re: what are the odds of massive failure of plus 4
@candle,
hi friend:
me, you, somebody else... we are technic but not all people that read this forum are electronics technic, so to prevent some letdown I think that it's honest to make explicit the features and the limits of what it's proposed.
(indipentently if I/you/others are proposing something...)
If the original RAM are present on motherboard (and no other mod as cutting traces/desolder chips is done) an extra 64K(or more)RAM (on cartridge or on CPU socket) will be in conflict ALWAYS at each cpu-ram access (and also TED-ram access) independently if the new ram is SRAM, DRAM,magnetic-core RAM, PAGED, BANKED, ...
If you think that a project of mine have some bug/critical issues/ambiguity in the explanation/others...
PLEASE TELL ME IT! because an honest technical conversation is the way to improve a project, and to make clear what it can do and what it can't.....
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Posted By
candle
on 2019-07-28
16:48:58
| Re: what are the odds of massive failure of plus 4
i can't make technical opinion on a project i don't know nothing about - never seen schematics, vhdl code, or even a board layout
all i can tell is that 6502plus4 board is up and running, 256k of Hannes mode memory expansion is working as it should, and CSORY mode is not doable in current design, as it uses 16k banks instead of 60k (or 48k) and i simply didn't know about that when i was designing the board
implementing this is not hard, but i'll have to redo the pcb to accomplish this task
thing is, i don't know if its worth the fuss
all demos i've tryed and do actually load from sd2iec work fine with Hannes mode, and CSORY seems to be utilised mostly by disk copying software
simple retouch would give me 512k of Hannes mode and 176kb in CSORY mode - but i don't know if this is good enough
ok, little update
i've managed to re-make PLA chip inside little CPDL and i've made a board for it
seems to be working just fine, all pins, including chip select for speech module are emulated
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Posted By
MMS
on 2019-07-30
03:09:45
| Re: what are the odds of massive failure of plus 4
Thank you for the updated infos.
Well, I should go to the attic and find my 3 or 4 dead Plus/4s, and check what should be swapped. 8501 and PLA are highly probable, and then I am lucky Less fortunate when TED is dead.
About 256KB RAM: I think it is a major step forward for mankind , and 512KB as a future in Hannes mode would be super.
As a remark: the original Macintosh with 68000 CPU + 384×256 resolution + GUI released with 128K, and was able to manage MacPaint and MacWrite. The finally successful (and MS Office compliant) version had 512KB, and it was able to manage postscript and so.
According to my personal view 256KB is nice and enough for a 8bit computer, and 512KB in 1984 was enough to support a really legendary and successful 16bit computer of the period (with similar resolution, Amiga required for the top-notch gfx and multichannel music more memory to be on the safe side, namely 1MB).
512KB would be enough to keep in memory a disc based graphical adventure game's all scene's picture at the same time.
So it is a pretty huge RAM (even 256K too).
PS: sorry for the previous typos, I had battery issues on keyboard
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Posted By
MCes
on 2019-07-29
10:04:33
| Re: what are the odds of massive failure of plus 4
with some precautions the C16/PLUS4 PLAs can be reproduced also with GAL22V10, and a strange assembly make them also mechanically compatible with PLUS4, and 1551 cart too....
https://postimg.cc/gallery/3fn2ha05m/
P.S.
How can I post image directly?
How can I will be a "registered user"?
Thanks
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Posted By
SVS
on 2019-07-29
12:50:47
 | Re: what are the odds of massive failure of plus 4
@MCes: 1) I suppose you are already a registered user, since your name appears in the post;
2) To upload directly you can try to click [Features] then [Plus4WorldUploader], but if it fails to work, just send the stuff via email to Csabo or Luca.
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Posted By
MCes
on 2019-07-29
14:46:50
| Re: what are the odds of massive failure of plus 4
@SVS
I'm not a "member" yet: I'm writing as guest, so I can't use the "forum image uploader".
I just written to Luca (we are italian: same language...).
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Posted By
SVS
on 2019-07-30
07:42:19
| Re: what are the odds of massive failure of plus 4
...same language me too 
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Posted By
MikeZ
on 2019-07-30
07:55:51
 | Re: what are the odds of massive failure of plus 4
Here is another data point. I bought 4 plus 4s in 1985-1987 expecting to be able to swap parts in years to come. But, all 4 eventually had TED failures.
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Posted By
MMS
on 2019-07-31
18:10:22
| Re: what are the odds of massive failure of plus 4
Actually, 4/4 TED defect does not sound to fit to the "normal" defect pareto we know.
PLA, 8501 and even the memories tend to fail.
Especially C16, but also the Plus/4 has the PSU troubles too. nothing special, same as the C64, but in C16 the zeners were really too weak.
Are you confident, that there was no gaming involved with fancy autofire joytisck (TED current overload) before the defect?
Or they arrived with defective TED?
Because this is a fact, that the TED has no protection on the joystick port.
In that case you really need the TED protector for TLC, otherwise after a TED change the same story will happen.
Also Luca mentioned those adapters, that use GND and not the select line (if I remember well), these also do not help on the TED lifespan. The reomval and connection of joysticks also a potential risk.
(in fact, the mini DIN connector outer shielding better lead the current, than the C64's DB9 plastic housing.)
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Posted By
MikeZ
on 2019-07-31
05:51:19
| Re: what are the odds of massive failure of plus 4
No. No joysticks at all. Just programming. Made lots of use of user port programming the Plus4 as a microcontroller.
There was also a ROM failure. That I fixed by cloning one of the good ones with Eprom burner.
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