Finally, a cheap C16 / +4 / C116 PLA replacement! (That anyone can make at home)
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- Опубліковано 19 лют 2021
- Daniël Mantione to the rescue again! He created a new PLA replacement, this time for the 264/TED machines: the Commodore 116, 16 and Plus4. This GAL-PLA is just as easy to make as the first
--- Video Links
More information about the TED/264 PLA:
www.freepascal.org/~daniel/c1...
You can buy one here:
www.sellmyretro.com/offer/det...
Make your own PCBs at PCBWay:
www.pcbway.com/project/sharep...
C16 on the fly PAL/NTSC switching:
• NTSC or PAL? One C16 t...
C64 GAL PLA:
• Can you replace your C...
TL866 Plus MiniPro EPROM programmer: (to program GAL chips)
amzn.to/3urrBh8 (or search eBay/AliExpress for TL866 Plus)
Trailblazer (Game I was playing at the end of the video)
thekingofgrabs.com/2020/01/03...
-- Tools
Deoxit D5:
amzn.to/2VvOKy1
store.caig.com/s.nl/it.A/id.16...
Jonard Tools EX-2 Chip Extractor:
amzn.to/2VazxDS
www.jonard.com/Products/EX-2-...
Wiha Chip Lifter:
amzn.to/3a9ftWw
www.wihatools.com/precision-c...
O-Ring Pick Set: (I use these to lift chips off boards)
amzn.to/3a9x54J
Elenco Electronics LP-560 Logic Probe:
amzn.to/2VrT5lW
Hakko FR301 Desoldering Iron:
amzn.to/2ye6xC0
Rigol DS1054Z Four Channel Oscilloscope:
www.rigolna.com/products/digi...
Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier:
amzn.to/3adRbuy
TL866II Plus Chip Tester and EPROM programmer: (The MiniPro)
amzn.to/2wG4tlP
www.aliexpress.com/item/33000...
TS100 Soldering Iron:
amzn.to/2K36dJ5
www.ebay.com/itm/TS100-65W-MI...
EEVBlog 121GW Multimeter:
www.eevblog.com/product/121gw/
DSLogic Basic Logic Analyzer:
amzn.to/2RDSDQw
www.ebay.com/itm/USB-Logic-DS...
Magnetic Screw Holder:
amzn.to/3b8LOhG
www.harborfreight.com/4-inch-...
Universal ZIP sockets: (clones, used on my ZIF-64 test machine)
www.ebay.com/itm/14-16-18-20-...
RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI)
www.retrotink.com/
Plato (Clone) Side Cutters: (order five)
www.ebay.com/itm/1-2-5-10PCS-...
Heat Sinks:
www.aliexpress.com/item/32537...
Little squeezy bottles: (available elsewhere too)
amzn.to/3b8LOOI
--- Links
My GitHub repository:
github.com/misterblack1?tab=r...
Commodore Computer Club / Vancouver, WA - Portland, OR - PDX Commodore Users Group
www.commodorecomputerclub.com/
--- Instructional videos
My video on damage-free chip removal:
• How to remove chips wi...
--- Music
Intro music and other tracks by:
Nathan Divino
@itsnathandivino - Наука та технологія
I love how these amazing machines are still supported by the community.
Yep. Commodore, long gone. Community? Still going strong.
they aren't amazing they're shitty and cheap. what is amazing is the community supporting them.
Drug dealer trick for opening small ziploc bags: hold the seal with your thumb and forefinger and "rub" it sideways back and forth. It should pop open at the sides and then you can pull it all the way open.
Hahaha!! Well thank you :-)
I've wanted to get a c64 for 15 years ever since Katrina destroyed my childhood machine I'm glad to see your videos about all of the commodore machines
Awesome! My first computer was a C-16, given by my grandpa. Still have it and recently recapped it (by someone who knows his stuff). :) This is great to keep it going.
It was also my first computer. I learned to program thanks to that computer, I even learned some assembly language with the MONITOR command ... How nostalgic.
@@starfleet-verdadero9808 Indeed, pitty kids don't learn it like that anymore. It really gave me insight into the basics (pun intended). Still applies today as well. Though I went on to become a biology scientist, I recently quit and am returning to programming. :)
I can't wait to see the first C64 to have ALL of the original chips replaced with homebrew PCB's. lol.
Although the GAL16V8 isn't manufactured anymore, there are several manufacturers making compatible parts -- for example, Microchip/Atmel's ATF16V8 is still manufactured and should be for a while (they usually give a few years notice).
It still amazes me as to how much work people put into things like this, and then put it all out on the internet for all to see and make themselves, very impressive stuff... :)
C16 was my first home computer. Brings back memories of spending Christmas Day and most of boxing Day trying to get my first game to load from tape. Xzap the game that sent me on a life long journey😁
Same here, Christmas 1984 was awesome!!!
@@StuartCowan I remember my naïve little 8 year old self yelling excitedly at my dad to type the answer YES at the C16 READY prompt :)
It was also my first computer. I learned to program thanks to that computer, I even learned some assembly language with the MONITOR command ... How nostalgic.
@@starfleet-verdadero9808 That's cool, yeah, the built in monitor was awesome and the ability to change game code on the fly was really awesome!
Ahhhh the trusty Commodore 16… my first ever computer!
It was also my first computer. I learned to program thanks to that computer, I even learned some assembly language with the MONITOR command ... How nostalgic.
Awesome! The PLA died in my Plus/4 just over a week ago.
@Mr Guru Dangnabbit. Useful for diagnostics though so I shall look to get one anyway. :)
@@Crashedfiesta Just skip the socket and it will fit perfectly in a Plus/4.
I never lived in era when those machines were the thing and neither am working or educated in anything tech involved, but thanks to this kind of videos I gained so much more understanding of how they work this is amazing. Thank you for all your work! On those videos I was always impressed how much love those machines gets. Also how much time will pass when we will be able to build all new parts C64 or different computer? I guess it is all down to if anybody will manage to recreate all the chips as FPGA? It will be interesting anyway.
Well... it is really rewarding that these computers do not just serve nostalgia, but also are of value to people who haven't used them. I understand the reason: Modern computers are of disgusting complexity, in order to understand computers you have to get something simpler. Nevertheless, it sure is a motivator dig up all the rusted knowledge from the golden years and get into Commodore computers again. These computers are old, they won't come back outside our community. But we, the children of Commodore, are also skilled computer experts. We have knowledge to share.
Actually there is a guy that re the 7501/8501 cpu as fpga. It supports even the illegal opcodes!
Kudos to him for finding and creating these solutions.
I've succesfully repaired many 16/116/+4 using ROM based PLA replacement.
Thats stuff we like to see (I think😅) got a broken 116 so love to see more replacement stuff. Thumbs up👍🏻and thank you Daniel!
On the one hand, I've just watched an 18 minute 39 seconds long infomercial for Daniel's products. On the other hand, I've just watched an _interesting_ 18 minute 39 seconds long infomercial for Daniel's products! I don't even have a Commodore computer to need this stuff for, yet I'm glad to see them being kept working.
Thanks, Adrian, and Daniel too!
Very nice indeed! Props to your good self for the demonstration and Daniel Mantione for his excellent and generous support.
A suggestion:
This is absolutely not a nit-pick and is obviously not remotely necessary. If I ever need one of his PLA replacements I'd be tempted to spin my own PCB layout from Daniël's design such that the GAL is on the underside of the PCB. In combination with either cutting out the middle of the PLA socket or replacing with pin-strip headers you'd have a marginally neater solution...
...or just use Daniël's PCB and carefully bend the GAL's legs through 180deg after programming.
Hey Adrian, your videos are awesome, love to see all of them.. You know, after seeing you having such a awesome basement full of cool stuff and doing all those repairs, made me want to start learning more about electronics and now I have repaired some old consoles and that felt great... Thank you for giving this great incentive and giving the opportunity to know more about electronics. Thanks for your great content! keep up the good work..
Another outstanding video!! Great job, Adrian!!
Adrian, I really enjoy your videos. I worked in the electronics field until I was medically retired in 2012, I miss it.
Great stuff for my C16 and plus4! I believe you did a review on that FPGA replacement, but it was like 100 euro or more. Thanks for the video!
Christmas 1984 was a Commodore Christmas in our house! Happy days!
The game at the end reminds me a lot of SKYROADS the 1993 DOS Game
Yeah! It is called Trailblazer and it was originally programmed on a stock c16 then ported to c64
I think it's great that more and more solutions are being found for these kinds of problems.
there is even someone who is now working on a VIC chip replacement for the commodore 64 it already works, soon that will be available as well.
get better and better :) is even better you don't need them but can happen to all of us,
Daniël Mantione is also a Dutchman just like me, just a lot smarter haha
Another great video of saving retro-computer by replacing with new design parts.
this kind of stuff is amazing for preservation!
Hurrah! A 'let's get right to it' without the dreadful 'without further ado'.
I agree it is far easier to solder pin headers if they are stuck into something. I like to use a small breadboard for this purpose, since it will be much larger than a board of this size and therefore easier to handle if you don't have small hands.
keep up the great work Adrian 🕹 ♥
Just got my Plus/4 up and running.
Excellent video thanks! Great to see these projects helping to keep our classic machines going. Scarcity of parts is something which has always concerned me..
Opensource software and hardware? That’s awesome, big thanks to the author of this project.
Here in Russia we call it "tsanga" - the collet connector as Your favorite IC socket type. And we DO think quite positively of that type of connector.
Once again great job of fellow dutchman Daniël. I hope he can make a open source replacement of the 8501 and/or TED chip.. keep up the great work... nice to have a full video of making this Adrian!
Another fantastic video! Commodore all the way! 😁👍
While watching the game demo screen, did anyone else feel the irrational need to jump every time a gap appeared on the play field? 😋
Haha. That game is quite hard too!
I hope your not suffering like the 8 Bit Guy from the awful weather conditions, much support from germany!
Hi. Good video as per normal. Thanks for brightening my saturday
Nice video Adrian. The Plus/4 was my first computer so good to see they can be kept going.
18 minutes? Heresy! ^
the so called "mini" videos are 3x longer :D
I had a plus 4 only for a short time as it was robbed. I did buy one from teacher at my school it shut down after 10 to 20 minutes took it back this was last day of school he says see me after 1/2 term I was left not happy. I did not know so much did go in to them. Would like to build one or get hold of one. I did do ram packs for the ZX81 were you had 2 backs of ram part my own work some from the old ETI magazine the ram was stacked with pin lifted to logic switching this was back in 1989 miss playing about. I jumped in to TV servicing there we had to make small PCB to replace frame IC's that were no longer made. But that was easy this stuff look like it will make my head hurt. Good work I keep coming back.
I remember a friend had a C16, probably about 1984 or so. It was likely the first computer I used, and I was enthralled even though it is very basic indeed. 😊
Love projects like this. :)
Now we need a competent sid replacement that isn't digital
That's a hard problem -- there are die shots in enough detail that it should be possible to recreate either the 6581 or the 8580, but actually doing that would be a lot of work, and then getting them fabricated would take a lot of money. Someone (not me, I don't have the time) should crowdfund an attempt to do this.
@@undefinednan7096 I'm all too certain the digital part can be done in fpga and the analog in smd
@@cheater00 fair enough, I thought that you actually wanted a custom IC, which could be cheaper __if there was enough volume__ (massive if there). I'm not sure how much analog circuitry the SID contained, but I know that it had at least analog filtering. The feasibility of doing it "to scale" (i.e. to fit in the same space as the original) would depend heavily on the amount and also on how small of packages one would be willing/able to use (for example, an 01005 is 400um x 200um, but using packages that small greatly increases assembly prices for low volume products). Conversely, if one doesn't care about the size, it can definitely be done once the SID's circuitry is fully reverse engineered to the schematic level (I don't know if this has been done). Assuming the SID's analog circuitry was designed properly (a big assumption), then it shouldn't be too hard to replicate its results (famous last words)
I just love watching your videos!
ice storm snippet footage. i would watch that. Great video as always.
Hi Adrian, Another great video, if you want to link other videos you have produced or other videos others have produced you can use the youtube cards, which will place a notice in the upper right hand corner when you want to reference other videos. You can also keep placing them in your description as its a handy place to go to.
Not sure why, but all three of my PLAs work completely fine in my C64s. I love seeing that people are keeping these delightful old beasts running though!
It's luck although if you have the original Signetics chip, those are super reliable. It's the Commodore made versions that is very unreliable.
While the PAL16V8 may not be produced any more, the ATV16V8 (which is the same functionally as the PAL variant) is available from mouser.
au.mouser.com/_/?Keyword=ATF16V8B&bws=1
The ATF16V8 is re-programmable so if a mistake is made you can program it again.
Exactly, ATFs are cheap and easily obtainable replacements for GALs (including other types like 22V10) and can also be programmed by the TL866 (-II) programmer.
For the Berg (later Dupont and now Amphenol) Mini-PV connectors you mention--the official recommended crimping tool is very expensive new, but they've been making it for so long you can find really old ones much cheaper on eBay. Using a more specialized crimping tool makes a big difference in how strong the resulting connection is.
These were premade cables and I assume those are garbage not the real non clone connectors. I should look for a crimper maybe it can revive these cheap cables
@@adriansdigitalbasement we use the molex SL series connectors a lot at work, and the SL female connectors are compatible with the typical berg square pin headers. (The reverse is not quite true, a male SL crimp won't really go into a header socket or breadboard).
The SL crimping tool we use is around $300-400 new I think which is much cheaper than the Berg crimper (over $1000 new, but can be as low as like $100 used)
Now the 264s are completely repairable - well, nearly. Only the "ThED" TED replacement needs to be completed :)
Well, of course it would also be better to have a new CPU, instead of replacing the 8501 by an 6510, and maybe even replacing the 6510 by an 6502 xD
You sung a lot of praises for the guy who came up with the mod/chips and said where to buy them. I think because of this you should say whether or not the video is sponsored - even if it isn't. (Also, for the record, I have no problem if it is)
ATF16V8 is the chip used in the replacement
One of the logic gates is done outside the gate array in diode logic (Fran would be proud!)
You can choose: ATF16V8, GAL16V8 and even PALCE16V8H work flawlessly.
Mistake number 1: Double leaf sockets are a million times better than 'nice looking' machined pins sockets
Mistake number 2: Yes, there are chips compatible with GAL18V8 which are still being made and sold, just look for ATF16V8 and they will do just as good a job but consume only a small fraction of the power.
I'd love to get hold of a plus 4, had one when I was young and really wish I'd kept it..
Awww, too short!
Very awesome!!!
great video.
I saw when you bridged the pins at 8:41 even if you fast forwarded the video ... :)
nice one Daniël
I have a c16 and a c116, however I havent used them in decades so Im hoping they will work when I get a chance to test them again later this year
Check your PSU thoroughly before you fire up! Or possibly fry up😀
Adrian must not be into drugs if he has trouble opening small baggies..
Where do you think he learned what a pain they are?
Ha ha. Great video. Very concise and clear explanation of a subject I barely understand.
woah watch what you say bruh
@@kittopersonal744 I suppose you don't understand humor. And I am certainly not your 'bruh'.
@@jondough76 if so then how would i know that bruh is basically a meme?
I notice a lot of these things are built with NOS Lattice GAL chips. I wonder if the designers are aware that Microchip still make 16V8 and 22V10 compatible programmable logic chips, brand new. I've used one for an "Unrainer" replacement for the PAL chip in my Spectrum +2, programmed it with my TL866II Plus
Do you have an emergency gen? I have a portable one that I can tie in via a transfer switch for key circuits. Heat, refirigerator, some lights and outlets... And I have a backup for that if necessary.
Those sockets at 8:55 are really poor. My Amiga 500 had some of those fitted and always crashed when I moved it.
I was lucky enough at the time to get access to a professional de-soldering tool. I removed them all and just soldered the chips back in.
It never crashed again when it was moved.
The round hole ones are much better. Those were the only type my company used.
Your Amiga came with single-wipe sockets. The one in the video is a dual-wipe socket. You can fight religious wars which is more reliable, but both the dual-wipe spring leaf socket and the round-hole socket are way more reliable than the sockets used by Commodore.
2:39 'fewer' scanlines. :D
I wanted to know if it is possible to change the C=16 pal in ntsc but that it is compatible with the programs and games in the pal system. Can the s-video output be improved like C=64? Beautiful video, the C=16 was my first computer and as a child I enjoyed writing basic graphics and sound programs, also had to write on sheets to print and save on tape. And I like this games: Magicians Curse, Xargon Wars, Pacmania, Robin Rescue, Guzzler, Video Meanies, Survivors, Qix, Tutti Frutti, etc.
I used the QuickShot with turbo fire
I like your monitor 🙂
Those programmers do work with Linux. I have installed the original software using Wine and have been using it numerous times to program the built-in flash memory of AVR microcontrollers. I have also read EPROMS with it (to get backup copies). I never tried programming EPROMS in Linux, but if the software communicates with the programmer, why should this particular function not work... ;-)
You don't even need wine, there are many open source versions of the minipro software on github, just compile and run.
@@DemetryRomanowski Thanks, I need to look out for those. My workbench PC is a bit underpowered, so something that runs natively is most likely going to run less slow than something that needs Wine.
I feel like those PLA replacements (C64 version) should be integrated into modern C64 replacement motherboards (like 64 Reloaded and such)
@Mr Guru You are right, I was thinking of CIAs.
C16 is my first love! fire starter!
Adrian, I have almost 8 game cartridges (plus4) and all working. all are same. is there any chance to modify any of it and create that diagnostic tool? I can send those cartridges to you? I don't know if those cartridges are helpful ? I'm not a hardware guy :)
You remind me of peppermint patti. Great job, appreciate it.
GAL 16V8 and 22V10 are still available new from Microchip from places like Digikey. They are sold as ATF16V8 and ATF22V10. I found the only problem is some programmers enable the power save mode of the 22V10, which means the chip freezes when pin 4 goes high.
The ATF22V10 is a bit problematic indeed, also because the first version of the TL866 doesn't support it and it also is only available in fast speeds. The ATF16V8 is just as usable as the GAL16V8, I bought some. Nevertheless, don't worry too much about the fact that they are out of production, a lot of these chips were made and stocks on the secondary market are bulging. It is absoltely no problem to buy them new-old-stock or used and this will be the case for a long time to come.
@@danielmantione The problem is that the atf22v10 has a completely different (and undocumented) programming algorithm to other GAL types... there is an open source schematic for a programmer (search for "atfblast"), but it attaches to the parallel port which is another inconvenience nowadays...
If it uses a GAL16V8, could it not also be able to use an Atmel ATF16V8B? I bought some of these from Digi-Key. I have a TL866II+ programmer and it supports both GAL and ATF. The reason I bring this up is while the GAL chips are discontinued, I think the Atmel variants are still being made.
Yes, the ATF16V8 works perfectly. You can also use PALCE16V8H. Discontinued is not a problem though, these chips are everywhere and there is way more supply than there are TED machines in existance.
Adrian, are you interested in a PAL C16 that is under the open sky since about 2010? It was already not working, and had a blown fuse. There might be zero usable parts left inside, but it would be a nice trip to try make it working again. I may try to ressurect it, but I won't go any further than doing this PLA mod, if the PLA is suspect in it. If I fail, I may send it to you if you are interested. I might not even try to repair it, just send directly to you as-is, because I have no C16 parts, you have plenty, and I won't invest too much into it because of its condition. I guess the keyboard is gone after that many years in the weather (the springs surely turned into solid rust), but the keycaps were looking OK last time I saw it. Though I can't promise I'll send it to you until I know the shipping costs - I'm in Hungary :-) .
You can still get new 16v8s from Atmel / Microchip.
How does the added ram help the machine?
I keep envisioning a history whee the 128 had a better graphics mode and a conversation between bill herd and the company grunts that sold him on a pn internally made chip went different.
What would change if the 128 had better adoption
The Plus/4 has 64K of RAM, therefore games designed for the Plus/4 don't work on the C16... unless you upgrade the RAM.
You mentioned 15ns or 25ns GALs work. The kit seems to come with a GAL16V8B. At least from Lattice and other vendors, there are a lot of GAL revisions over the years (no-suffix, A, B, C, D also). Will any GAL16V8* work, or is there a specific reason to use only the 'B' revision?
Any GAL will work. You are also in no way limited to 15 and 25ns. I haven't tested 10ns and 7ns myself, but unlike the C64 there is no critical timing in the 264 PLA, so I expect they will just work. The different revisions of the GAL are generally compatible. They are not compatible for programmers, may have sliight real-world timing differences and differ in their built-in pull-up resistors, but none of this should matter for the TED computers.
I noticed the solder bridge before he did. I was yelling at the screen lol..
Nice
3:37 _"Finding a cpu for this machine is very difficult"_
Does it use some kind of special version of the 6502, like the "6510" in the VIC-64?
I actually though it used an ordinary 6502, much like the VIC-20 or PET.
It's yet another variant of the 6502 but different than the 6510 CPU used in the C64.
Adrian, you mention the chip programmer you used. I looked on Amazon for that model number and there are TONS of them from various companies, some with special adaptors for different chip configurations and such. Is there a particular one you recommend? I've been wanting to get something like this for a while so I could burn Kickstart ROMs, and other chips like C128 option ROMS and such. Would appreciate any recommendations you can give...
They can't program kickstart ROMs, not without some adapter. No sure on specifics as I use my Data IO for that. I put a link in the description to a programmer buy totally not sure if it's legit. I bought mine years ago and from China directly. Really not sure what all the brand names are about now. :-(
based on the stickers on your cabinet, I wonder how many conferences we have both been at and I didn't realize you were there (LinuxCon/PyCons/KubeCon/Defcons/etc)
Damn Daniel
cool.
Hi, did you update the test catridge between NTSC and PAL?
I wonder because in the PAL test ist shows the kernal rom as ok and 6510v 1?
Looks like the same build version. It's just missing the CRC value for the NTSC ROM, where the PAL one is included.
Yeah so what is happening is I took the PAL modified ROM (that is all that exists) and modified it for it worked on NTSC machines -- so it's unofficial. I think I sent Rob a copy of my NTSC ROM to include in the diagnostic cart -- but I never updated it.
Amiga on the Lake sells a 6502 CPU replacement for the TED-based machines... hope you'll review one of those in the future as I'd like to see your thoughts on it before getting one for one of my own sick Plus/4.
I have an upcoming video on another such solution -- one you can make yourself. Keep your eyes peeled.
Do you use a fume extractor or mask when soldering? If not is there "safe" solder that doesn't have things like lead in it?
Of course! Lead-free solder is nowadays mandatory for commercial electronics, so you can buy lead-free solder anywhere. I doubt the fumes are healthy though, but some ventilation should help a lot.
Yup my plus 4 has a black screen
You said the chips are no longer made. Microchip/Atmel still make brand new parts that might be compatible?
Yep, TL866II is supported on Linux and macOS with gitlab.com/DavidGriffith/minipro
It doesn't have all the functionality of the windows software, but that can also be used under WINE. (I use it for testing ICs)
Adrian, the IC pin leg straightener.... where did you get it? Where can I get one? We see it used about 8.50. Also, with regard the Tl866, I have the later model which loses the ability to program the older EPROM as it cannot handle the higher voltage, however I have cobbled together a 2nd ZIF socket that plugs into the main one where you can use power from an external source (bench supply) therefore giving you the best of both worlds. Give me a shout if you want the schematics.
This is the link from the video where he discussed it:
www.amazon.com/JAMECO-BENCHPRO-Pin-Straightener-Tool/dp/B00B888W5S/ref=as_li_ss_tl
Looks like it’s out of stock now, but you may be able to find it elsewhere.
@@adambaranek Thanks! That's great! Also, did Adrian ever talk about that silver IC removal tool he uses? Really need one of those as well.
There is a link to that in the video description -- chip extractor
Any replacement for TED chip? My Plus/4 shows proper text mode but graphics mode looks like sync is off.
I have a problem with my c16 sometimes it word great then other day I have to switch it on fast it will come on . Any idea what the problem
There was another very cheap PLA replacement for these machines and it was the M27C512-90B6 from ST but Groepaz did everything he could to discredit it with a ton of falsehoods. Nowadays, if you look on eBay or anywhere else looking for that part number, all you'll get is Chinese fakes...
Adrian, i will ask a favor, could you have the name or formula of deoxider? I have some apple 2 clones, amiga 500 and otherold computers with ic black pins
Hi Adrian, I tried using the original equations for the C64 PLA to attempt to emulate one missing signal from one pin, I did this using an EPROM , address lines signal in and data lines signal out, while this solution did produce a output (that seemed good) the machine still didn’t operate as it should have (there was no signal on the PLA pin before this mod, also note the EPROM piggybacked the PLA and shared the inputs)
Just wondering how the equations for this PLA specify timing...that info doesn’t seem to be in the file, just Boolean statements for outputs from given inputs...maybe just the chip architecture... might have to read up and follow the Arthur of this great piece of work. Excellent video, keep fighting the good fight. Pete, Yorkshire,UK
A GAL has a propagation delay: If you change an input, the outputs will update with a delay. The timing is influenced by the way the two GALs in the C64 are connected (RAMCAS should be last in order to avoid switching noises), further you can influence delay by means of feedback, so you can route a signal through the GAL twice and thus have twice the propagation delay.
There are 3 problems with using EPROMs: Timing, switching noises and logic levels. You can get some of these right by choosing your EPROM carefully, but not all of them. If you have a broken PLA, even just one pin, replace it. GAL PLAs are cheap enough that there is no reason to mess around with EPROMs any longer.
😊
6:04: @Adrian's Digital Basement: When you say, "the equations", do you mean the digital logic? I've heard people refer to gated logic or logic circuits or combinational or combinatorial logic, but I've never heard people just say "the equations" in this context. I'm genuinely a little confused by that.
In a GAL, you write the source code as boolean algebra, and therefore we speak of equations. However it is just digital logic with AND/OR/NOT gates.
@@danielmantione Thank you. TIL.
Hey Adrian (and anyone else who wants to address this...) When I was a kid, and had a VIC-20 (this would've been in the early 80s) and also a C64, 128, and a couple of Amiga systems through the years, one thing that drove me up the wall with the C= machines were those overscan bars. Was there ever any way by a 3rd party, through a hardware addon or some software trick that would let you make those smaller, or even just "zoom in" to the usable part of the screen?
I have an A1200 going into an Amiga M1438S multiscan monitor, and with one of the higher-res screenmodes i am able to extend the 800x600 standard format up to around 912x623 or so, which makes the entire screen usable.
There's reasons why they exist (mostly because the computer's timings and performance were low and they needed the overscan bars to leave the CPU time to do things since the CPU was directly involved in updating the screen...
They're much less prevalent in the Amiga, especially if you compare the same game against the Atari ST version of the same game - the ST required the 68K to do a lot of the graphics processing so they needed the overscan to shrink the amount of pixels and give the CPU some time on each scan line to do other work.
@@mikekopack6441 Indeed; the Amiga has all those lovely custom chips that lighten the load of the CPU quite drastically.
@@mikekopack6441 Thank you, and @BertyFromDK for your answers.
16:36 why isnt the kernal rom bad in PAL mode?