Course #1 - why you should NEVER use fast logic ICs with old/slow computers

[eslapion]

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[eslapion]

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[eslapion]

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[plazma]

Yes, sure slower speed logic is better and I acknowledge that. I prefer to use 74HCT series in C64 circuits.
74LVC & 74AHCT series was used because that was available from the component supplier in SOT case.

I tested with 469 & 466 with no problems. I also sent few for free to some test users. My design worked in a 466 where one other design failed.

And here eslapion is telling lies:

Sure enough everyone who used this product on boards 250466 had problems with it as this C64 board filters CASRAM.

Instead of changing the logic gate for the correct type, he redesigned his product to use an inverter on the secondary Chip Select line of the SRAM IC. It now works ok but he doesn't really know why. It so happens the inverter he chose is a Schmitt Trigger but he didn't even notice that part.

I know what a Schmitt Trigger is and use it on purpose in some designs.

Both 1.0 & 1.1 version have worked with all users in original 466 boards.
Problems have only emerged with new 466 clone boards where two users got problems.

On Amibay, on June 27th 2019, I announced I was going to offer a new product for the C64, called Saruman-64. It is a module which either replaces both 41464 DRAM on boards 250466 and 250469 or all 8 DRAM chips on all other versions of the C64 with some additional wiring.

Only 2 days later, I started a thread about it and immediately, a guy called Plazma indicated he was selling a nearly identical product.

That was a coincidence. I had no knowledge of your post and have never read it. The SRAM board was under work weeks before your post.
Instead few hours after my sales post you made your own sales post of an unfinished product with only rendered images.

I'm just ordering a new SRAM board "neatSRAM". It got all components under the PCB and uses slower SRAM & logic. It will be sent for free for the new 466 clone users. Later on it will be released at github for people who like to build their own.

[Mike]

That was a coincidence. I had no knowledge of your post and have never read it. The SRAM board was under work weeks before your post. Instead few hours after my sales post you made your own sales post of an unfinished product with only rendered images.

Before any priority discussion comes up here: a similar solution to operate a C64 with SRAM was already in development in the German Forum64 as early as 2011, with a small PCB to replace the two 41464 being shown already early 2017:

https://www.forum64.de/index.php?thread ... ost1125579, Post #52

[plazma]

Before any priority discussion comes up here: a similar solution to operate a C64 with SRAM was already in development in the German Forum64 as early as 2011, with a small PCB to replace the two 41464 being shown already early 2017:

https://www.forum64.de/index.php?thread ... ost1125579, Post #52

My design is based on the gerrits preliminary schematic in first post. Even though I got it from some other forum or FB group.

[eslapion]

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[eslapion]

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[Vic20-Ian]

This will be a useful thread for many people if it can stick to knowledge sharing without the emotive posts.

Thank you for putting this together, I learned a few things.