PLAnkton EV, a new version of PLAnkton

[Deleted member 14264]

Hi everyone,
PLAnkton has been a very popular product since it's introduction back in August 2015. More than 3000 units have been sold since, a number which I find stunning after all this time.

Back then, me and co-creator Fredric Blåholtz expected to sell a few hundreds. With lots of luck maybe 1000. We were quite surprised with the demand and the very positive reception.

However, time has passed and a few potential improvements have been noted.

For one thing, a genuine Commodore PLA signals at a voltage between 3.7 and 4.5 volts. Usually hovering around 4.3 volts. PLAnkton feeds the XC9536XL core CPLD at 3.7-3.8 volts and while this is within the requirements to be representative of a good PLA, it is beyond the recommended operating voltage defined by the manufacturer. At the same time, it is somewhat too low when compared to a genuine Commodore PLA.

Also, even when using the low power mode of the XC9536XL and slew rate limiters built into this type of IC, PLAnkton's slew rate signaling remains much higher than a genuine old PLA.

PLAnkton EV resolves these issues by adding a CMOS buffer which will be powered at 4.3V while the CPLD is now powered at 3.3V. The buffer uses legacy CMOS technology which has a low slew rate nearly identical to that of vintage technology PLAs and is powered at a voltage which also allows it to signal a higher voltage, now also nearly identical to that of vintage technology PLAs.

Half a dozen units have already been made and thoroughly tested.

EV means Exact Voltage.

More information and photos to come.

 

[Sardine]

It's really fantastic 30 - 40 yr old equipment is supported like this.

Excellent work.

 

[Deleted member 14264]

It's really fantastic 30 - 40 yr old equipment is supported like this.

Excellent work.

Thanks for the positive comment! Here's a photo of the first tested prototype.

 

[demolition]

Never had any issues with my PLAnkton and as far as I know, not many other have either but I guess that doesn't mean that there is no reason to improve on it. The reduced supply voltage might help make it last 30 instead of 20 years.
I assume that the addition of the extra IC will increase the cost - any idea yet how much it will affect the end price? Since the first version worked as well as it did, I don't think most people would like to pay significantly more for a difference that is mainly theoretical.

For the full retro-experience you should also make a version that emulates the first original PLAs with the faulty passivation layer so it dies after a month or so - 'it's not a bug, it's a feature'. It might help you sell a lot more devices. Or, at least wait to announce it on April 1st.

 

[Deleted member 14264]

Never had any issues with my PLAnkton and as far as I know, not many other have either but I guess that doesn't mean that there is no reason to improve on it. The reduced supply voltage might help make it last 30 instead of 20 years.
I assume that the addition of the extra IC will increase the cost - any idea yet how much it will affect the end price? Since the first version worked as well as it did, I don't think most people would like to pay significantly more for a difference that is mainly theoretical.

For the full retro-experience you should also make a version that emulates the first original PLAs with the faulty passivation layer so it dies after a month or so - 'it's not a bug, it's a feature'. It might help you sell a lot more devices. Or, at least wait to announce it on April 1st.

It's a sad fact people tell me too rarely about the problems they might have with my products. Knowing about the problems helps me greatly to improve the products I make and sell.

On one of these rare occasions, somebody indicated they had problems with the FastLoad Reloaded cart in which the original 7407 open-collector buffer was replaced by a cheap CMOS equivalent. The consequence is the FLRL cart would now work correctly with a genuine Commodore PLA but not with any PLA replacement that uses the XC9536XL. Unfortunately, the FLRL cart is not the only product where TTL ICs have been replaced with CMOS chips without care to make sure the replacement is TTL level compatible.

PLAnkton EV's higher signaling voltage fixes any compatibility problem these products may have.

In the case of the FLRL cart, it was possible to fix the problem by removing the cheap CMOS IC and putting the correct 7407 TTL IC but people usually frown at doing that because they'll tell you it works fine with the 'real' PLA so it should be your PLA replacement which is 'fixed'.