MMC1 MAPPER impossible to do with discrete parts

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darleiv
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MMC1 MAPPER impossible to do with discrete parts

Post by darleiv »

would anyone know of a schematic that uses discrete parts for the mmc1b mapper? because at most I found one that uses pal - I wanted to make a pure logic gate
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Ben Boldt
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by Ben Boldt »

“Pure logic gate”; do you mean only 74xx/CD40xx chips, or literally only logic gates (AND,NAND,NOR,etc)? I.e. are you allowed to use shift registers, counters, flip-flops? What is the purpose that you don’t want to use programmable logic? After all, you will need to use a programmable ROM, correct? Does it need 100% MMC1 function implemented?
lidnariq
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by lidnariq »

No-one has already done the MMC1 using just discrete logic, but I see no reason it wouldn't be doable.

However, modern debugging emulators are definitely up to mapper hacking MMC1 into a de-serialized version that should be much cheaper to build PCBs for.
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aquasnake
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by aquasnake »

Someone has implemented mmc1 with greenpak, which has the most simplified peripheral wiring scheme, and has fewer package pins than qfp44 of traditional Altera/Xilinx
darleiv
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by darleiv »

aquasnake wrote: Tue May 10, 2022 11:51 pm Someone has implemented mmc1 with greenpak, which has the most simplified peripheral wiring scheme, and has fewer package pins than qfp44 of traditional Altera/Xilinx
interesting. would have the link
darleiv
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by darleiv »

Ben Boldt wrote: Mon May 09, 2022 11:28 am “Pure logic gate”; do you mean only 74xx/CD40xx chips, or literally only logic gates (AND,NAND,NOR,etc)? I.e. are you allowed to use shift registers, counters, flip-flops? What is the purpose that you don’t want to use programmable logic? After all, you will need to use a programmable ROM, correct? Does it need 100% MMC1 function implemented?
hehe what the fun of doing that already exists. in cpld and pal i found many projects. some functional others not. nostalgia is in making a half meter board with only 74x 40x logic ports
darleiv
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by darleiv »

lidnariq wrote: Tue May 10, 2022 7:57 pm No-one has already done the MMC1 using just discrete logic, but I see no reason it wouldn't be doable.

However, modern debugging emulators are definitely up to mapper hacking MMC1 into a de-serialized version that should be much cheaper to build PCBs for.
I thought exactly about that. that it is possible to make any signal used in these mappers only with 74xx
lidnariq
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by lidnariq »

Is the objective a fun discrete logic project? Go for it! and then please come back and share pictures :)
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Bregalad
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by Bregalad »

The problem with it is that you'd need an absurdly high amount of gates to get just the shift logic to work 100% identital to the MMC1.

Using a programmable logic PAL I was able to replicate MMC1's functionality with 3 chips only.
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Ben Boldt
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by Ben Boldt »

We should have a challenge. Design 100% compatible MMC1, only use 74xx chips (any, including shift registers, rare ones etc), minimum # of chips wins.

How many do you think it takes? What’s realistic?
calima
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by calima »

Number of entrants: 3 of which 2 will fail :P
darleiv
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by darleiv »

forum member named fisher said he has the mmc1 skeleton ready. did he win the championship? fisher wins :roll: 8-)
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Fisher
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by Fisher »

darleiv wrote: Mon May 16, 2022 4:05 pm forum member named fisher said he has the mmc1 skeleton ready. did he win the championship? fisher wins :roll: 8-)
Oh that sketch. :lol:
That's one of my tries to build a simplified Master System mapper, as stated on the top right corner of the page.
I'm trying to use some ideas discussed with lidnariq on SMSPower forums some time ago.
However, it has a fatal and sloppy mistake on it that won't allow all the banks to work as intended.

I think I did another draw trying to correct that mistake, but right now with most if my "hobby" stuff packed it is kind of difdicult to find it.
I'm not sure if I took a picture of it or not... :roll:

Unfourtunatelly, the last storm had made some damage to my home and right now all my personal projects are "on hold".
Hopefully I'll soon be able to finish the repairs that are simple, but for an amateur builder as me takes many times the regular time. :|
darleiv
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by darleiv »

Fisher wrote: Mon May 16, 2022 5:01 pm
darleiv wrote: Mon May 16, 2022 4:05 pm forum member named fisher said he has the mmc1 skeleton ready. did he win the championship? fisher wins :roll: 8-)
Oh that sketch. :lol:
That's one of my tries to build a simplified Master System mapper, as stated on the top right corner of the page.
I'm trying to use some ideas discussed with lidnariq on SMSPower forums some time ago.
However, it has a fatal and sloppy mistake on it that won't allow all the banks to work as intended.

I think I did another draw trying to correct that mistake, but right now with most if my "hobby" stuff packed it is kind of difdicult to find it.
I'm not sure if I took a picture of it or not... :roll:

Unfourtunatelly, the last storm had made some damage to my home and right now all my personal projects are "on hold".
Hopefully I'll soon be able to finish the repairs that are simple, but for an amateur builder as me takes many times the regular time. :|


say it's from mmc1 . you win.
I have a sketch here of mmc1b full synthesized by Russian Cluster M. but i can't see how to make it become TTLs
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Bregalad
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Re: MMC1 MAPPER impossible to do with discrete parts

Post by Bregalad »

Ben Boldt wrote: Sat May 14, 2022 6:40 pm We should have a challenge. Design 100% compatible MMC1, only use 74xx chips (any, including shift registers, rare ones etc), minimum # of chips wins.

How many do you think it takes? What’s realistic?
The problem is that doing so is completely useless. Many chips technically existing in the 74xx series are rare or even very rare. You could play and make a schematic with them but you'd never be able to even try if this works. And even then, to get the exact replica of an MMC1, you'd need at least 5 chips to get just the shift register to behave the same. The major problem is the shift register who is 5 bits, and internal registers are 5 bits, when most chips have 4 of the same element. This thing alone increase the # of chips needed to get it done.

On the other hand, it's possible can use PAL22V10 or GAL22V10 chips which are common and still available, and only a 5 of them can replicate a full MMC1 who is identical (3 are enough if you use CHR-RAM). But even when suggesting doing that, I was critiquized this way crazy and that using a single CPLD chip is cheaper and easier.
Useless, lumbering half-wits don't scare us.
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