IMPORTANT: It is recommended to use the "AT28C64" profile and not the "AT28C64E" as shown in the video. The "E" profile uses tighter programming cycles and can occasionally fail to program the NEAT2364
I've wanted to make some programmable 24 pin EPROM replacements myself and the necessary pin arrangements between read and write modes just made it complicated and ugly, so I abandoned the idea. The use of pogo pins never occurred to me, very smart and neat solution!
@TheRetroChannel Your product must be doing really well. :D Once I got the notification your stuff was in stock it was sold out before I could an order placed. :D Good job on making something that everyone seems to want :)
I feel like the next step would be to have multiple banks in the flash rom that can be programmed all at once (show as a '256 device to the programmer) but still maintain the 24 pin footprint, but adding pins for remote switch or jumpers to pick the bank to present to the 24 pin output... (eg, replace the 24 pin graphics/font rom in the Apple IIc, but put multiple fonts in there, switchable at runtime)
@@TheRetroChannel This has been done in some other projects. They used a tiny 4-position dip switch block surface-mounted type. With 4 switches it is possible to change to any one of 16 images. A 2-position dip switch gives 4 choices which will cover all the C64 roms and one extra for jiffydos or something else.
Hi! Thank you for this great work. I've ordered 6 of them, because I often repair C64 and other Commodores. Today I had an CBM 610 on my bench. All 3 ROMs were missing. So I tried your "NEAT 2364" and they worked perfectly fine in this rare machine. So you can add to your list of compatible machines also the CBM 610. Thank you again and greetings from Austria to Australia :-)
Awesome! Thanks for letting me know. I notice the character rom in those is only 4K in size, did you just duplicate the rom to fill up the entire 8K on the NEAT?
@@TheRetroChannel I did not even notice, that the character ROM is much smaller. I just took the original Char Rom from another - similar - machine, read it with my TL866 using the profile of a 2764 and wrote it to the AT28C64.
A neat device. I actually like the idea of the switch, rather than using solder blobs as has been suggested. It adds only a few cents to the materials cost. Everyone to their own opinion, of course.
Yeah I may do another version with extra options if I can squeeze them in. This one is designed to be straight forward so I avoided adding extra switches etc
good design. Fun Fact I would have loved something like this back in the 1980s. I was warranty & tech support for Pro-Digital services in Brisbane for commodore, amstrad and atari home computers
Using a transistor and two resistors you can make a RTL inverted CS signal for the Atari systems I think. Not much room for it on that board, but simple enough of a mod IMHO. Could also use any NAND or NOR gates (tie input together) or 7404 NOT gates, but most of those are more than you need.
As I mentioned in the video, the 2364 should be filled when replacing smaller sizes. And there are a number of systems that are currently untested, Rudy is aware of this
An SMT 2N9001 would make a space-conscious inverter for those Atari systems-you might have to use a red PCB or something to prevent them from getting mixed up or add another switch.
@@TheRetroChannel Or put a logo on the top for whatever thing it's for, Commodore chicken lips C64 logo, Atari 2600 logo or whatever. For the inverter all you need is the same type of thing that's on our C128 QuickCart... tiny little SOT23 74HCT1G04 or similar which takes up sweet fa space :-) Package is often called SOT23-5 or SOT553 (1.7mm x 1.7mm). Or use a DFN1010 which is only 1mm x 1mm. Or a DFN0808 which is only 0.85mm x 0.85mm... seriously tiny heh!
Great idea and very useful! I'll keep this in mind for my next repair! Love the small footprint and adapter designs. Have you considered adding a bank select, for an external switch? This way you can quickky switch between multiple versions (2, 4 or as many as you can fit?) that have benn preprogrammed. I found this useful on a trs80 model 1 to switch between ram diagnostics, level I, and level II rom images.
Good idea but fitting that onto the PCB without using the top side could be tricky. I also wanted to keep this as simple to use as possible. A more advanced version with this option could be a future project
That non-standard ECB 1.0 ROM is interesting. The change at offset $162C seems to be a botched fix for a PMODE bug in 1.0. It actually makes the problem worse. ECB 1.1 from the archive has the correct fix.
I also got a rom replacement called neatROM 2364 and neatROM 23256. Will receive them tomorrow assembled from JLCpcb. I hope the names don't cause confusion.
@@TheRetroChannel A 23256 is only 28 pins no matter what so easily replaced with a 27256. It's probably one of those shared projects that doesn't actually work lol. I got caught like that once... reversed the whole thing, fixed the issue and released all files, schematics and gerbers on my site lol For the name, rename to NEATO, sounds more aussie-like :-)
Excellent work. For inverted chip select option. A single gate XOR function in a tiny TSSOP5 package is available. 74HC1G86. About 2.3 x 1.2mm. One pin for invert or not and the other to program it. Solder blob OK in this case. ?
That is a great idea. I like the programming adapter. Can you actually take care of those mask programmed chip selects that are configured differently in Commodore machines?
@@TheRetroChannel I've repaired several PETs. All the machines I worked on had ROMs that are compatible with 2716 or 2732 or might have been 2532. Either way they are only 2k or 4k.
nice idea ... BUT 20$ for this thing + adapter + programmer .. how many eproms can one buy for 20$ ... doen't make sense to pay 20$ (and they are sold out haha) And other solutions have a usb connector to easy install a rom image
No need to have a switch for programming mode. You can add a pogo pin that bridges 2 pads instead so it will never be accidentally in programming mode outside of the programmer
Very ingenious solution to use pogo-pins to bring additional signals to the part. But I do not quite understand the need for the switch. This seems expensive, hard to build and prone to user error. If pull-ups/pull-downs are not an option, maybe a solution with a 3rd pogo-pin could do the trick?
The switch is only a minor cost, and saves the end user needing to do any soldering. It actually works by disconnecting a line when in programming mode so a third pogo pin wouldn't work
@@TheRetroChannel Maybe I would have to know more about the way the programmer interacts with this IC. Does it use the RDY pin as well as the WE and OE?
The RDY pin is N/C on the AT28C64E. OE is active low but needs to go high when programming, neither pull-ups or pull-downs worked reliably in both modes. So OE and CE (also active low) are tied together, but require a switch or jumper to separate them for programming. WE however can be pulled up by a 10k resistor and the programmer is able to pull this low with minimal slew so it doesn't fail programming
Hi. Is the adapter sold separately? I went to your tinder shop and didn't quite understand? Although AU$21 postage to the EU is a bit rough, it's still a very good product.
The adaptor is sold separately but both options are now out of stock, there should be more available next week. As for postage, nothing I can do there unless I become CEO of Australia Post
What happen if i don't change it to programming mode and tries to program it? What happen if i leave it in programming mode and put it in my Commodore 64?
Programming them is not something that will be done 100's of times so you can save a few cents by removing the switch (which may only be used once) and replace it with 3 solder blob pads. A simple soldering iron can move the blob from one side to the other. Personally I wouldn't waste a switch on something that will only be toggled once or twice in its entire life. You could make a version with the switch as an option or design the board in such a way as to allow for adding the switch after if required.
For those who just want to play around with different roms or use it for a temporary replacement, it will be reprogrammed multiple times. Having a switch just makes it more user friendly and also removes the need for the end user to do any soldering. It's worth a few cents imho
@@TheRetroChannel Ok well that's even easier. Use a 2-position solder blob. Leave it without a blob, program it then add a blob to short those pads together. Or if the line is just low or high use a 10k or 4.7k pull-up or pull-down resistor so it sits at one level normally and the programmer can pull it to the other level by itself... switch not required ;-)
IMPORTANT: It is recommended to use the "AT28C64" profile and not the "AT28C64E" as shown in the video. The "E" profile uses tighter programming cycles and can occasionally fail to program the NEAT2364
Those pogo pins on the adapter are definitely a clever way to handle the write enable!
I've wanted to make some programmable 24 pin EPROM replacements myself and the necessary pin arrangements between read and write modes just made it complicated and ugly, so I abandoned the idea. The use of pogo pins never occurred to me, very smart and neat solution!
@TheRetroChannel
Your product must be doing really well. :D
Once I got the notification your stuff was in stock it was sold out before I could an order placed. :D
Good job on making something that everyone seems to want :)
Yeah they went quick sorry. The next batch should be ready in about a week
I feel like the next step would be to have multiple banks in the flash rom that can be programmed all at once (show as a '256 device to the programmer) but still maintain the 24 pin footprint, but adding pins for remote switch or jumpers to pick the bank to present to the 24 pin output... (eg, replace the 24 pin graphics/font rom in the Apple IIc, but put multiple fonts in there, switchable at runtime)
Yeah that could be a future project. I wanted to keep this one as simple and tidy as possible
@@TheRetroChannel This has been done in some other projects. They used a tiny 4-position dip switch block surface-mounted type. With 4 switches it is possible to change to any one of 16 images. A 2-position dip switch gives 4 choices which will cover all the C64 roms and one extra for jiffydos or something else.
Hi! Thank you for this great work. I've ordered 6 of them, because I often repair C64 and other Commodores. Today I had an CBM 610 on my bench. All 3 ROMs were missing. So I tried your "NEAT 2364" and they worked perfectly fine in this rare machine. So you can add to your list of compatible machines also the CBM 610. Thank you again and greetings from Austria to Australia :-)
Awesome! Thanks for letting me know. I notice the character rom in those is only 4K in size, did you just duplicate the rom to fill up the entire 8K on the NEAT?
@@TheRetroChannel I did not even notice, that the character ROM is much smaller. I just took the original Char Rom from another - similar - machine, read it with my TL866 using the profile of a 2764 and wrote it to the AT28C64.
@user-ji6yv5hw6w Ah ok, yeah that would work too. Nice
A neat device. I actually like the idea of the switch, rather than using solder blobs as has been suggested. It adds only a few cents to the materials cost. Everyone to their own opinion, of course.
👏👏👏
Thank you for coming up with this!
An optional inverter might be possible with a single transistor, a few resistors, and a DPDT switch. Could be very tiny.
Yeah I may do another version with extra options if I can squeeze them in. This one is designed to be straight forward so I avoided adding extra switches etc
I missed this comment and said similarly. A bit late. 😅
Dude just reinvented the EEPROM
That was nifty. I need some of these for sure
good design. Fun Fact I would have loved something like this back in the 1980s. I was warranty & tech support for Pro-Digital services in Brisbane for commodore, amstrad and atari home computers
Sounds like an idyllic job.
Way too cool!
Using a transistor and two resistors you can make a RTL inverted CS signal for the Atari systems I think. Not much room for it on that board, but simple enough of a mod IMHO.
Could also use any NAND or NOR gates (tie input together) or 7404 NOT gates, but most of those are more than you need.
Very nice all-purpose solution. ;)
This is great! Like the compact factor! 👍
Wow!! This is exactly the solution I am in need of! Thanks and great work! Will be trying them on several different Commodore PET computers
Those ROMs are not used on PETs. The PET uses smaller ROMs, 4k or 2k which are compatible with 2732 or 2716.
As I mentioned in the video, the 2364 should be filled when replacing smaller sizes. And there are a number of systems that are currently untested, Rudy is aware of this
An SMT 2N9001 would make a space-conscious inverter for those Atari systems-you might have to use a red PCB or something to prevent them from getting mixed up or add another switch.
Yeah, if I end up doing one that is compatible with Atari systems a different colour is a good option.
@@TheRetroChannel Or put a logo on the top for whatever thing it's for, Commodore chicken lips C64 logo, Atari 2600 logo or whatever. For the inverter all you need is the same type of thing that's on our C128 QuickCart... tiny little SOT23 74HCT1G04 or similar which takes up sweet fa space :-)
Package is often called SOT23-5 or SOT553 (1.7mm x 1.7mm). Or use a DFN1010 which is only 1mm x 1mm. Or a DFN0808 which is only 0.85mm x 0.85mm... seriously tiny heh!
Very neat, indeed, Sir! Great idea, it is a pity that you live in Australia and I in Europe. Shipping costs will be too high.
Yeah shipping is pretty exxy from Australia. It does sting less when purchasing multiple items 😉
Great idea and very useful! I'll keep this in mind for my next repair! Love the small footprint and adapter designs. Have you considered adding a bank select, for an external switch? This way you can quickky switch between multiple versions (2, 4 or as many as you can fit?) that have benn preprogrammed. I found this useful on a trs80 model 1 to switch between ram diagnostics, level I, and level II rom images.
Good idea but fitting that onto the PCB without using the top side could be tricky. I also wanted to keep this as simple to use as possible. A more advanced version with this option could be a future project
@@TheRetroChannel It's possible with solder blob jumpers. Resistance against solder blob jumpers is futile and you will eventually submit ;-)
well done! this is super cool.
That non-standard ECB 1.0 ROM is interesting. The change at offset $162C seems to be a botched fix for a PMODE bug in 1.0. It actually makes the problem worse. ECB 1.1 from the archive has the correct fix.
Awesome! Just what the Dr ordered. 3 for me! ;-)
Neat.
I also got a rom replacement called neatROM 2364 and neatROM 23256. Will receive them tomorrow assembled from JLCpcb. I hope the names don't cause confusion.
Haha, I guess great minds think alike. I'm sure it won't cause too much confusion, hopefully
@@TheRetroChannel A 23256 is only 28 pins no matter what so easily replaced with a 27256. It's probably one of those shared projects that doesn't actually work lol. I got caught like that once... reversed the whole thing, fixed the issue and released all files, schematics and gerbers on my site lol
For the name, rename to NEATO, sounds more aussie-like :-)
Brilliant and elegant solution, but all sold out :( Signed up for wait list !
Yeah sorry, very limited numbers in the first batch and my patrons get first dibs on new stuff. There will be more available in a week or so
Not sure if this is a workable thing, but it would be nice if printed labels could easily be inserted behind a transparent cover on top.
Missing Mr Lurch's Things Channel, Hope He's Doing OK!
I totally agree!
Excellent work.
For inverted chip select option. A single gate XOR function in a tiny TSSOP5 package is available. 74HC1G86. About 2.3 x 1.2mm. One pin for invert or not and the other to program it. Solder blob OK in this case. ?
That is a great idea. I like the programming adapter. Can you actually take care of those mask programmed chip selects that are configured differently in Commodore machines?
The only one that I know will not work is the VIC20 character rom as it uses both chip selects. Not sure at this stage about the PET machines
@@TheRetroChannel I've repaired several PETs. All the machines I worked on had ROMs that are compatible with 2716 or 2732 or might have been 2532. Either way they are only 2k or 4k.
Those Eproms which forgot what they were... Maybe attaching a large capacitor between plus and minus makes them remember 🤔
what?
Cool. I rebuilt my CoCo 1 from scratch and it still doesn’t work. But all the power rails are fine.
nice idea ... BUT 20$ for this thing + adapter + programmer ..
how many eproms can one buy for 20$ ... doen't make sense to pay 20$ (and they are sold out haha)
And other solutions have a usb connector to easy install a rom image
Great work .. ill bet they sell like hot cakes 😉
No need to have a switch for programming mode. You can add a pogo pin that bridges 2 pads instead so it will never be accidentally in programming mode outside of the programmer
That's not what the switch does
🍪
🤠🔫
Very ingenious solution to use pogo-pins to bring additional signals to the part.
But I do not quite understand the need for the switch. This seems expensive, hard to build and prone to user error. If pull-ups/pull-downs are not an option, maybe a solution with a 3rd pogo-pin could do the trick?
The switch is only a minor cost, and saves the end user needing to do any soldering. It actually works by disconnecting a line when in programming mode so a third pogo pin wouldn't work
@@TheRetroChannel Maybe I would have to know more about the way the programmer interacts with this IC. Does it use the RDY pin as well as the WE and OE?
The RDY pin is N/C on the AT28C64E. OE is active low but needs to go high when programming, neither pull-ups or pull-downs worked reliably in both modes. So OE and CE (also active low) are tied together, but require a switch or jumper to separate them for programming. WE however can be pulled up by a 10k resistor and the programmer is able to pull this low with minimal slew so it doesn't fail programming
Why cant the board directly put into the programmer, but needs the 28pin adapter in between?
Hi. Is the adapter sold separately? I went to your tinder shop and didn't quite understand? Although AU$21 postage to the EU is a bit rough, it's still a very good product.
The adaptor is sold separately but both options are now out of stock, there should be more available next week. As for postage, nothing I can do there unless I become CEO of Australia Post
Jupiter Ace
I guess this is an alrernative to using those socket adapters 27xx to 23xx ?
Yup
What happen if i don't change it to programming mode and tries to program it?
What happen if i leave it in programming mode and put it in my Commodore 64?
In both cases nothing dangerous will happen, it just won't be able to program or won't be read by the machine
Programming them is not something that will be done 100's of times so you can save a few cents by removing the switch (which may only be used once) and replace it with 3 solder blob pads. A simple soldering iron can move the blob from one side to the other. Personally I wouldn't waste a switch on something that will only be toggled once or twice in its entire life. You could make a version with the switch as an option or design the board in such a way as to allow for adding the switch after if required.
Or add another pogo pin to the adapter that automatically puts it into programming mode
For those who just want to play around with different roms or use it for a temporary replacement, it will be reprogrammed multiple times. Having a switch just makes it more user friendly and also removes the need for the end user to do any soldering. It's worth a few cents imho
Not possible unfortunately, the switch just disconnects a line when in programming mode
@@TheRetroChannel Ok well that's even easier. Use a 2-position solder blob. Leave it without a blob, program it then add a blob to short those pads together. Or if the line is just low or high use a 10k or 4.7k pull-up or pull-down resistor so it sits at one level normally and the programmer can pull it to the other level by itself... switch not required ;-)
I assume each unit ordered comes with a programmer adapter? What if I only need 1 or 2 adapters but like 6 eeprom units, is this possible?
They are sold separately for that very reason
@@TheRetroChannel Thanks for the feedback. I did not see that option on the store so I had to ask.
No worries. I think the options are not shown while they're out of stock. More are on the way