Posted By
MCes
on 2022-12-02
10:30:57
 |  chips replacement & mods
When a custom chip fail it can be a great problem, but fortunately some functions can be replicated by new chips &/or little circuits that sometimes have some optimizations,
and normally they need less power to work lowering the temperature inside the machine.....
1) CPU replacement for C16 or PLUS4 (C-MOS core: less power/heat but it can't manage the illegal opcodes)
2) replacement PLA: it's so thin that can be used inside PLUS4 too: it has been tested inside a PLUS4 and the keyboard closes without touching it!
3) 1551 replacement cartridge PLA: it's thin enough to let closing the shield inside the cartridge and the plastic shells... (it's on socket!)
4) 1551 replacement for 2523A (2525A) + 6510T
5) C16 full ROMset (all PLUS4 ROMs functions) into 1 C-Mos chip, C-Mos= less heat
6) Plus4 ROMset into 1 C-Mos chip, C-Mos= less heat
7) make your C16 PAL & NTSC, normal or jiffydos....
8) JiffyDOS for C16 or PLUS4, not only switchless: wireless! (Kernals will swapped on reset button pressing)
9) CPU replacement for C16 only (selected N-MOS core: it manage the illegal opcodes)
10) CPU replacement for PLUS4 only (selected N-MOS core: it manage the illegal opcodes)
11) A 64K S-RAM expansion with jiffydos and TV standard PAL/NTSC (with clock switch and default TV standard setting by a jumper) both selectables by "SYS"
12) A MOS6529A replacement that fit C16 and PLUS4 (only for keyboard driving: only WRITE activity..)
13) the "JUGGLER" Multimod for C16: 64k RAM, new CPU, new joy/keyboard port (TED latch fix) ESD protection for TED (and CPU) thread
.... and more coming soon!
replacement for 7501/8501 (C-MOS core)
NOTE: The core inside is a C-Mos CPU, so it can't execute any illegal opcode: if the SW contain illegal opcode it can't be execute properly.
replacement PLA: it's so thin that can be used inside PLUS4 too: it has been tested inside a PLUS4 and the keyboard closes without touching it!
replacement PLA for 1551 cartridge: it's thin enough to let closing the shield inside the cartridge and the plastic shells... (it's on socket!)
replacement for 2523A (2525A) + 6510T
 
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Posted By
MMS
on 2019-09-28
04:15:29
 | Re: chips replacement
Nice work!
With these replacements, there is a growing chance to revive, and keep running those failed machines!
Also, the value of a working plus/4 / C16 is higher (and increases continuoulsy) than an "untested" or not working one.
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Posted By
unclouded
on 2019-10-17
05:12:11
| Re: chips replacement
I was wondering about just this recently. I'd rather use a "C16 reloaded" than to risk original hardware for regular use.
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Posted By
MMS
on 2019-10-17
19:36:52
| Re: chips replacement
Sorry, but I suppose there will be no "C16 reloaded".
The scene is rather small, and the money required for such a project (especially low volume PCB production) is huge.
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Posted By
RobertB
on 2019-10-18
18:34:43
| Re: chips replacement
With the Ultimate 64 and 64Mini in production, I was thinking that C16/Plus4 cores would be good for those machines (a VIC-20 core announced for big brother, "the c64").
Truly,
Robert Bernardo
Fresno Commodore User Group
http://www.dickestel.com/fcug.htm
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Posted By
MMS
on 2019-10-20
13:09:31
| Re: chips replacement
Ultimate 64 is 215€
64Mini is nice, but does not work with the original keyboard or even with the housing.
Don't get me wrong, these are nice developments (like the C64 in joystick). But...
I know there will be time when no C16 or Plus/4 will worj with the original 1984 main components, but the recent developments may extend this time.
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Posted By
MCes
on 2019-10-24
15:20:59
| Re: chips replacement
Another little project: a Full ROMset for C16 to +4 ROMset!
It lower abot 100...110mA the supply current (1W of heat less inside your C16..) and your C16 appear as +4 (without 64k ram, parallel and RS232 port...), but remember that some function SW need the ram expansion... (the shortcut keys works on 16k also).
The extra ROM images can be deselect cutting the 2 wires.
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Posted By
MMS
on 2019-10-24
17:46:16
| Re: chips replacement
Hi MCes!
Actually I am interested in the ROMset for C16 to reach lower temps inside the C16, but I have no use of the 3+1 SW, never used it.
Any idea, what could fit into the 16+16K EPROM space, has more use and can be activated with a button press with eg. a pop-up window?
I will be more than ready to order for Plus/4 too a ROM set, but 32KB could have a better use 
Please PM me, if you are ready to produce some for me, and how we may manage the rest of the matters.
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Posted By
MCes
on 2019-12-21
09:23:27
| Re: chips replacement
This little board replace the 4 ROMs inside the PLUS4 saving about 25% of all power absorbed.
Consequently the internal overheating will drop of about 25% making fresher yor TED, CPU, as all chips inside!
Also your PSU will be less stressed....
 
 
Its particular shape and its cuttable branches permit, in a future,
to reuse the kernal socket for installing an alternative kernal (as JiffyDOS)
look this my little project: it make selectable the video standard (PAL/NTSC) and a second kernal (in example CBM/JIFFYDOS).
I used the little window near the RF connector to put the selectors....
 
 
Now I'm proposing a JiffyDOS "wireless" solution:
it will be sufficient to plug it on kernal socket and it will work without piercing the case and WITHOUT EXTRA WIRES!
How to handle switching between kernals?
The PLUS4 will boot-up with standard kernal (I prefer always that on standard boot-up the machine seem not modified....)
the kernal will swap each time you will press the reset push button (the original will become JDOS, or JDOS will become the original one), but the reset via software will has no effect.
Obviously it's designed to fit inside the PLUS 4 without cause problems at correct case closing.
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Posted By
MMS
on 2019-12-20
09:03:56
| Re: chips replacement
That switchless Jiffy change could be done on C16 too?
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Posted By
MCes
on 2019-12-20
11:05:58
| Re: chips replacement
@MMS
It's arriving.....
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Posted By
MMS
on 2019-12-20
15:29:42
| Re: chips replacement
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Posted By
MCes
on 2019-12-21
09:19:51
| Re: chips replacement
Wireless JiffyDOS for C16.... (jumper is for PAL/NTSC selection)
 
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Posted By
unclouded
on 2020-04-22
07:08:28
| Re: chips replacement
Are these available for sale? I'm interested in a PLA and CPU substitute for a C16.
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Posted By
Stinaris
on 2020-04-22
11:09:02
 | Re: chips replacement
Wow.
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Posted By
MCes
on 2020-11-23
03:43:06
| Re: chips replacement
And now...... the "CPU4C16"
a CPU replacement for C16 only (selected N-MOS core: it manage the illegal opcodes)
This solution has:
A) normal sw N-MOS 6502 behaviour (as 8501, illegal opcode included)
B) The I/O bits are at right places: the self-turbo routine (loaders) will work
C) R/W line is put on 3state and HOLD as 8501 timings spec
D) TBC (Time Base Corrector) technique applied to help the CPU, also into the "worst case", for meeting the correct bus timings
E) each 6502 that I use on it is selected for 2 specs: 1) it has to be an N-Mos, 2) it has to match to the specifics timings (more than 2MHz)
Remember that N-MOS 6502 chips are discontinued, often on market the sold chips are refurbished and relabelled with a label different to the old one:
chips marked as "6502" may not be N-Mos as it have to be, and vice versa (C-MOS, so no execution of the illegal opcode).
I found a chip labelled as "W65C02S" (10MHz C-MOS) that is a 1MHz N-MOS!!!!!
Now my C16 is:
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Posted By
pocketscience
on 2020-09-25
05:04:51
| Re: chips replacement
Are these for sale anywhere? I've a non-working Plus/4 (dead TED and CPU), and a separate board with missing PLA, TED, CPU, and ACIA... and finding parts, especially here in Australia, is challenging.
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Posted By
MCes
on 2020-11-23
05:39:11
| Re: chips replacement
you can see...
TED: https://www.sellmyretro.com/offer/details/45437
ACIA: it can be also the Rokwell R6551AP
I can supply the PLA.
I can supply the CPU replacement 85MC01 (it's a C-Mos so it can't perform illegal opcode).
A specific N-Mos version is under development but is not ready, so if you have also a C16 you can use the C16s CPU on PLUS4 and use my "CPU4C16"replacement in your C16.
See also if you are interested in my other projects, because unfortunately we are on the opposite side of the world and the shipping cost could affect, so I can certainly be convenient if you need more items.
Contact me for details
And now......
the "CPU4PLUS4", a processor replacement for PLUS4!
It's essentially a "CPU4C16" shaped for fitting the PLUS4 space...
Another good point....
A C16 "plug & play" modify (without use of solder iron....) that allows:
1) 64K S-RAM expansion
2) jiffydos switchable with a simple "SYS53240" (no holes on case, no wires to motherboard)
3) TV standard (PAL/NTSC) switchable with a simple "SYS53245" (no holes on case, no wires to motherboard) (the starting TVstandard is jumper selectable)
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Posted By
Chronos
on 2020-11-23
08:35:48
 | Re: chips replacement & mods
Great News!
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Posted By
MMS
on 2020-11-24
11:10:42
| Re: chips replacement & mods
These are really great improvements! Especially for US and other NTSC customers can try out those great converted games on this platform. (The recently made one are all NTSC compatible, AFAIK)
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Posted By
Retro Recollections
on 2020-11-26
13:25:06
 | Re: chips replacement & mods
Exciting developments! I have the C16 RAM module on my main C16 but these other improvements are very interesting.
I have a spare C16 that lacks a working CPU also 
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Posted By
Mad
on 2020-11-26
15:16:29
| Re: chips replacement & mods
Wow! Finally one solution for illegal opcodes, too! Cool! Working without lax (Zeropage),y is not doable for me especially for soft sprites where 2 extra cycles for an tax is a real slowdown. great news! I think others like Bubis and the other Demopeople use a lot of the full range of illegal opcodes available! Congrats for that achievement! Finally!
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Posted By
MCes
on 2020-11-27
12:46:52
| Re: chips replacement & mods
Thanks a lot for your appreciation!
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Posted By
zzarko
on 2021-01-13
11:13:25
| Re: chips replacement & mods
I have bought several of MCes's solutions and I can say that they work great. A few more are on the way to me soon...
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Posted By
seff
on 2021-01-14
07:30:35
 | Re: chips replacement & mods
Any chance for TED replacement?
FPGATED?
https://hackaday.io/project/11460-fpgated
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Posted By
marcos64
on 2021-02-03
04:50:14
| Re: chips replacement & mods
@MCes: Where can I order a CPU4C16?
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Posted By
marcos64
on 2021-02-04
04:21:38
| Re: chips replacement & mods
Thanks. I have to register there.
Just did it, waiting for approval.
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Posted By
MCes
on 2021-02-04
12:55:24
| Re: chips replacement & mods
@marcos64
you can also directly email me!
And NOW:
A MOS6529A replacement that fit C16 and PLUS4 (only for keyboard driving: only WRITE activity..)
   
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Posted By
marcos64
on 2021-02-05
04:48:05
| Re: chips replacement & mods
I've already registered so I do it there. Could be interesting for other items for the future too.
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Posted By
Snocksman
on 2022-06-05
14:50:07
| Re: chips replacement & mods
Hi ! I am very interested to get more information about the mod shown in the post "Wireless JiffyDOS for C16.... (jumper is for PAL/NTSC selection)"... Where can I buy it ? ...or how to build it on my own ? I there a github page with gerber files ?
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Posted By
MCes
on 2022-06-06
10:38:52
| Re: chips replacement & mods
@Snocksman
whoever wants one of my items can write to me directly in private (preferably by email)
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Posted By
Snocksman
on 2022-06-06
14:49:14
| Re: chips replacement & mods
@MCes I would like to send you an E-Mail but in your Profile I can't see your Mailaddress... Do I need to register in the Forum first, to see it ?
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Posted By
SukkoPera
on 2022-12-02
12:31:49
| Re: chips replacement & mods
@seff: Cassette port should be ok, no idea about illegal opcodes. But I really wouldn't recommend using a "fully synthetic" replacement, at least until some form of 6502's can still be found. The less you emulate, the more compatibility you can take for granted.
EDIT: Sorry, didn't notive how old the question was.
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Posted By
seff
on 2022-12-05
12:27:33
| Re: chips replacement & mods
@SukkoPera
I would love to have a completely "synthetic" C264 of course.
I know this will never happen due to the TED. ;-((
Though I was hoping for an FPGA-emulated TED.
One day the 7501/8501 CPU can possibly be fully emulated including the cassette port and illegal instructions.
Will wait...
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Posted By
SukkoPera
on 2022-12-06
03:35:19
| Re: chips replacement & mods
I don't see the point in fully synthetic recreations of old computers, those are close to emulators IMHO (yes, I know they are different in nature), always full of small little bugs and never reaching perfection (and this is due to the amount of guesswork that is always necessary when developing such things). But apart from that, I like to see all the different OLD parts work together, not some ultra-modern thing pretending to be something else.
I'd love to see standalone open-source synthetic replacements for the 8501 and TED, but only in order to cope with the eventual lack of replacement parts for repairing old machines, but until we can get spares, those will always be my first choice.
BTW, work on the TED is undergoing.
Anyway, this is just my opinion, take it as it is, I know we are entering religion wars here .
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Posted By
Byteman
on 2023-05-31
16:56:57
| Re: chips replacement & mods
Hi All,
https://github.com/ZXByteman/Fake6523 - finally got it working in 1551. Unfortunately both my 1551s have broken heads (15Kohm resistance on Red wire), so only basic data exchange between +4 and 1551 was checked. Waiting for replacement mechanisms and then will check fully.
Unfortunately timing diagrams from 6523 datasheet do not correspond to the actual access diagrams inside 1551. Datasheet states that all signals should be kept stable whel _CS is low, but in fact, during WRITE transaction R/_W is triggering when _CS is active low. So some code was added to handle this situation.
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Posted By
SukkoPera
on 2023-06-01
12:09:03
| Re: chips replacement & mods
Hey, great work! Thanks for sharing!
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Posted By
Imperious
on 2023-08-19
07:17:23
| Re: chips replacement & mods
I made up one of the Monotech "MOS CPU REPLACER" boards for my plus/4. So far I haven't found anything that doesn't work properly. I've tried most of the new games as well as demos and gfx disks. I was having some locking up issues but it's due to my pi1541 overheating. I removed the case and underclocked it and no more loading problems. It was reported that Slipstream locks up on a 64k modded c16 but I played through about 5 levels then restarted the game ok, so maybe an issue with the c16 mod. I tried Rockwell and UMC 6502's successfully. I don't have any MOS 6502A's. I did need to move a few capacitors on the plus/4 board. I soldered the board to the plus/4 pcb after testing in another plus/4 of mine. I did have one of those 6510 adaptors in this machine but they are as good as useless with only a handful of games working with it. Just one word of caution, this pcb uses some 0402 capacitors and they are not easy to solder without some decent magnification, flux paste and some thin solder. I used JLCPCB as PCBWAY quoted about $120+ US Dollars whereas I payed $13 for 5 boards from JLCPCB delivered. Here's the link to the Github page for anyone interested. https://github.com/monotech/MOS_CPU_Replacer
 
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Posted By
Retroshire
on 2023-08-19
10:45:21
| Re: chips replacement & mods
@imperious please try to run the demo Metapharstic 80%, is stucks on all CPU replacements of this moment.
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Posted By
Imperious
on 2023-08-20
07:26:55
| Re: chips replacement & mods
Yes You are correct it does not work. It loads the 2 Yellow text screens then halts there.
It doesn't work in Vice either, halts with a cpu jam error. It does work ok in Yape.
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Posted By
MCes
on 2023-08-20
09:46:54
| Re: chips replacement & mods
I had a look at https://github.com/monotech/MOS_CPU_Replacer project, and I encountered more than one problem, for example:
1)The DATA-BUS behavior is not performed correctly during the write cycle and this could cause conflicts on the DATA-BUS with other chips or peripherals (it may be useful to observe the solution of the Commodore engineers on the VIC20 schematic)
2)I have doubts about the times that can be guaranteed by the "/0000-0001" address decoder, some measurements should be done on it
3)The internal port write method does not match all 6502 timing specifications, this activity can become device dependent, noise dependent, etc. Consequently some instability of the tape/disk devices can appear.
4)The behaviour associated at AEC signal doesn't match the correct timings, it could generate instability into dynamic RAMs
5)This adapter will have problem with C16 that use the standard 16Kram: it will corrupt the ram memory at $4000/1, $8000/1, $C000/1, memory tha can be used by SW or by the basic operative system.
6) Remember that N-Mos 6502 (N-Mos= execute illegal opcode, C-Mos doesn't) are discontinued since a lot of years, so normally you can get relabelled chips from china which can hide a C-Mos chip or... another kind of chip! (I found a relabelled 6502 that is a wellworking parallel port 6522).
Some of these "6502" chips don't work at all...
For a correct 8501 timings matching: the 6502 on the adapter has to be better than a base 6502A (A= 2MHz) so I call the N-Mos chips that I select for my adapters as "6502A+"
SIDENOTE:
if we want talk deeply about a specific project, please open a new thread about it, thanks
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Posted By
SukkoPera
on 2023-08-20
14:19:17
| Re: chips replacement & mods
Let me add something: the Monotech CPU Replacer is an open source effort. This means that if you can make it better, please do so! Collaborate with the author, join the project or at least report the issues and help improve it!
Open source is like that, never hesitate to propose your help, even if it seems irrelevant: just contributing a logo, a manual, a 3D model, a bug report or whatever is always welcome and brings the project further!
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Posted By
Imperious
on 2023-08-20
20:25:58
| Re: chips replacement & mods
Hey I'm more than happy here if the admin move the conversations about projects unrelated to MCes designs to new threads.
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