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PostPosted: Thu May 14, 2015 6:53 pm 
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Hi so I have been pounding my head the last few weeks with information and while I have obtained much needed info there are still a few areas I would like additional help on.

First I'm a long time collector and have a very extensive collection. My collection can be viewed in a thread at Atari age or at my photo bucket.

http://atariage.com/forums/topic/193595 ... try2754794

http://s14.photobucket.com/user/icemanx ... t=3&page=1

I will start w/what I know or at least think I know :)

nes games consist of 2 files chr "character" and prg "programming"
on original nes games these files can be various sizes most being 128 Kb or 256 Kb.

I will use a NES-TLROM-03 board as my discussion here.

That board has a 32 dip chr but prg can be 28 dip or 32 dip. This is where I start getting confused. Why a board can have diff. prg dips. Examples will be bases loaded 3 which has a 32 dip prg and days of thunder which has a 28 dip prg but they are both a NES-TLROM-03 board?

I have come up with this: the 32 has 4 extra pins pin 1=a17, pin 2=/ce pin 32= +5, and pin 31=+5, my theory is I could use say bases loaded donor and install a 32 dip chip and maybe program that chip staring at pin 3 and ending at pin 30 and not use the other 4 pins. Or I could just toss a 28 dip eprom in the board and not use those 4 slots at all?

As far as eproms go I have purchased some AMD AM27C128 and AMD AM27C256 chips both 150 speed. These are only 28 dips so it appears I need to get some 32 dips. However the 32 dips are not made that small. I purchased the AMD AM27C256 chips before I realized all 256 chips have to be 32 dip.

My theory from what I have read Is that I can still use these AMD AM27C256 28 dip chips for 128 files by doubling them. This now gets me to the 32 dip chips. From what I read I need to get a chip like AMD AM27C010 I am thinking 120 speed as they are plentiful. I figure on 128 files I will copy them 8 times and on 256 files I will copy them 4 times.

How am I doing so far? Thanks for all help in advance.


Last edited by icemanxp300 on Thu Jun 25, 2015 9:13 am, edited 2 times in total.

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PostPosted: Thu May 14, 2015 7:48 pm 
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icemanxp300 wrote:
Why a board can have diff. prg dips. Examples will be bases loaded 3 which has a 32 dip prg and days of thunder which has a 28 dip prg but they are both a NES-TLROM-03 board?

Smaller chips need less pins, it's as simple as that.

NES memory chips are 8-bit, meaning that each unit of information contained in them is 8 bits, or 1 byte. This means that 8 pins are necessary to carry the information out of (or into, if we're talking about RAM) the chip.

Aside from these data lines, we need address lines to tell the chip the position of the byte to be read (or written, if RAM). I don't know if you're familiar with the binary system, but with 1 bit, you can count 2 positions: 0 and 1. Add another bit and you double the amount of positions you can count, because you can count 0 and 1 with a 0 in front of them (00 and 01) and also with 1 in front of them (10 and 11). Each bit you add to the address doubles the amount of possible combinations, allowing you to count twice as many positions. If the chip has more memory positions, more address lines are necessary to address them all.

Additionally, the chip needs pins to let the power go in and out, like a light bulb, so that's 2 more pins. Finally, some control lines are necessary to to activate/deactivate the chip (sometimes multiple chips are connected to the same data bus, and they can't all output data to the same wires, so some chips have to be disabled at certain times) and tell it whether it's supposed to read or write data.

On the NES, 28 pins is enough to go up to 128KB of PRG-ROM (8 data lines, 17 address lines, 1 power, 1 ground and 1 chip enable), but you need 1 extra address line to go up to 256KB, and that would be 29 pins, so that chip has to use the next available package (32 pin). Because of the way the system was designed, CHR-ROM is different, it needs 2 chip enable lines (there are two conditions that have to be met for the chip to be enabled and outputting data), so a 128KB CHR-ROM must have 32 pins.

Quote:
I have come up with this: the 32 has 4 extra pins pin 1=a17, pin 2=/ce pin 32= +5, and pin 31=+5, my theory is I could use say bases loaded donor and install a 32 dip chip and maybe program that chip staring at pin 3 and ending at pin 30 and not use the other 4 pins.

What do you mean "not using the other 4 pins"? These are important signals, the chip will not work properly (or even at all) if you simply ignore them...

Quote:
Or I could just toss a 28 dip eprom in the board and not use those 4 slots at all?

Unfortunately, EPROMs need more signals than mask ROMs, because they need things like a programming voltage and a write/read signal, so you won't find a 28-pin 128KB EPROM/EEPROM/FlashROM. The largest programmable 28-pin chip is 64KB.

Quote:
As far as eproms go I have purchased some AMD AM27C128 and AMD AM27C256 chips both 150 speed.

You should know that the numbers in the chip names represent kilobits, not kilobytes. A kilobyte is 8 times more than a kilobit, so the AM27C128 can only hold 16 kbytes and the AM27C256 only 32 kbytes. These are only enough for NROM or CNROM games on the NES... yeah, the earlier titles.

Quote:
From what I read I need to get a chip like AMD AM27C010 I am thinking 120 speed as they are plentiful.

Yes, that chip is 1024 kbits, or 128kbytes. Chips ending in 020 are 2048 kbits (256kbytes) and chips ending in 040 are 4096 kbits (512kbytes), the largest ever used in commercial NES games. If you can, always buy the largest chips, because you can always connect the higher address lines to GND and simulate smaller chips with them (i.e. a 27C040 can be used for a 128KB game just fine, not only for 512KB ones).


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PostPosted: Thu May 14, 2015 9:18 pm 
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Wow thanks for the info. I know there is a diff. between bits and bytes. It appears I goofed and wasted $$ on useless chips.

So it appears 128KB = 1Mb

Ahhh so let me write this out so I comprehend better lol.

1 Kilobyte KB = 8 Kilobits Kb
1 Megabyte MB= 8 Megabits Mb

so for 128 KB I need at least a 1Mb chip
and for 256 KB I need at least a 2MB chip.


So AMD AM27C010-120DC 32 dip would be acceptable for 128KB files

So AMD AM27C020-120DC 32 dip would be acceptable for 128KB files or 256KB files

So now to go back to the pin question. Lets basically skip what I said.

http://www.raphnet.net/electronique/nes ... inouts.txt

that shows prg 128KB pinouits for 28 dip and 32 dip mask roms.

Lets use the two donors listed above:

Bases loaded 3 and days of Thunder.
http://bootgod.dyndns.org:7777/profile.php?id=721
http://bootgod.dyndns.org:7777/profile.php?id=614

Both are NES-TLROM-03 boards both have 32 dip CHR roms but days of thunder is a 28 dip prg where as bases loaded 3 is a 32 dip prg.

Basically dot can't be a donor board!


Last edited by icemanxp300 on Thu May 14, 2015 9:47 pm, edited 1 time in total.

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PostPosted: Thu May 14, 2015 9:42 pm 
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I realize that looking up the pinouts that my theory would not work.

http://pdf1.alldatasheet.com/datasheet- ... 0-120.html

So would I just program the chip normally and rewire a few?

TKROM & TSROM (mapper 4):
PRG socket:
Bend up pins 1, 2, 24, 30 and 31 (or cut tracks 2, 24, 30 and 31)
Solder pin 2 to hole 24 (A16)
Solder pin 24 to GND (OE)
Solder pin 30 to hole 1 (A17)
Solder pin 31 to hole 2 (A18)
CHR socket:
Bend up pins 1, 2, 22, 24, 30, 31 (or cut tracks 2, 22, 24 and 30)
Solder pin 2 to hole 24 (A16)
Solder pin 22 to hole 31 (CE or CHR /A13)
Solder pin 24 to hole 2 (OE or CHR /RD)
Solder pin 30 to hole 1 (A17)


Whats confusing about this tutorial here is solder pin 24 to GND (OE). Pin 24 is GND OE, solder to itself?


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PostPosted: Thu May 14, 2015 11:04 pm 
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icemanxp300 wrote:
Basically dot can't be a donor board!

You can still use the board. Note that even though the PRG-ROM has 28 pins, the board still has the extra 4 holes (they're filled with solder though, but you can melt it off). On the few boards I have personally checked, those holes had the correct connections. But even if they didn't, it would just be a matter of lifting the pins and wiring them to the correct places.

Forgive me for not verifying you rewiring notes, but I'm really tired right now and that requires a lot of attention...


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PostPosted: Fri May 15, 2015 8:27 am 
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tokumaru wrote:
icemanxp300 wrote:
Basically dot can't be a donor board!

You can still use the board. Note that even though the PRG-ROM has 28 pins, the board still has the extra 4 holes (they're filled with solder though, but you can melt it off).

Forgive me for not verifying you rewiring notes, but I'm really tired right now and that requires a lot of attention...


Why did I not notice that lol. Thank you. As far as the pinouts it came from this site.

http://nesdev.com/NES%20EPROM%20Conversions.txt


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PostPosted: Fri May 15, 2015 11:47 am 
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icemanxp300 wrote:
Wow thanks for the info. I know there is a diff. between bits and bytes. It appears I goofed and wasted $$ on useless chips.

AM27C128 is 16 KiB, and AM27C256 is 32 KiB. So let's make some lemonade.

With two AM27C128, you can make Thwaite, which has 16 KiB PRG ROM and 8 KiB CHR ROM. You'll have to patch it to add MMC3 init code.

With two AM27C256, you can make Adventures of Lolo 2, Burai Fighter, or To the Earth. All these are MMC3 games with 32K PRG ROM and 32K CHR ROM. You could also patch most CNROM games to use MMC3 bank switching and make those.


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PostPosted: Fri May 15, 2015 12:57 pm 
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Thread moved to Reproduction board.


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PostPosted: Fri May 15, 2015 1:56 pm 
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Why is it relevant that the guy is new to programming if this doesn't really even have to do with programming?


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PostPosted: Fri May 15, 2015 2:29 pm 
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Espozo wrote:
Why is it relevant that the guy is new to programming if this doesn't really even have to do with programming?



I assumed buying a "programmer" made me new to "programming"

I will change topic if I can.


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PostPosted: Fri May 15, 2015 2:41 pm 
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icemanxp300 wrote:
I assumed buying a "programmer" made me new to "programming"

Well, can you tell me what this does?

Code:
start:
  ldx #$00
  lda #$28

loop:
  inx
  cpx #$18
  beq done
  sta $00,x
  bra loop

done:
  rts

icemanxp300 wrote:
I will change topic if I can.

You can. Edit the first post on the page, and it will have a title over the box where you type that will display the title. You can then type where the title is to replace it.


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PostPosted: Fri May 15, 2015 6:26 pm 
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Dude it's over. I meant New to programming eproms, chill-out. I already did edit title but some sites have a time limit that you can edit, that's why I said I would "try". I'm new to the site. The title is changed everyone is happy.


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PostPosted: Fri May 15, 2015 6:44 pm 
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I wasn't meaning to offend you. Sorry. (I'm not being sarcastic. I was curious if you were actually trying to learn something like that.)


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PostPosted: Fri May 15, 2015 8:53 pm 
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Espozo wrote:
I wasn't meaning to offend you. Sorry. (I'm not being sarcastic. I was curious if you were actually trying to learn something like that.)


It's cool, I'm not offended I thought you were upset over the thread. I'm just trying to make repros of nes and snes games and whoah it is much more complicated than I initially thought. Going from knowing nothing to doing it. I have a friend who was helping me but it's been awhile since he did them.

I have barely touched the burning or programming of eproms yet. I purchased a GQ-4X True USB Willem ECU EPROM BIOS SPI Flash PIC AVR universal Programmer. I read mixed feelings about it, but it was only $100. I also purchased a cheap eraser just in case.

I ordered the wrong nes chips as I was pounding so much info at once lol. It's cool though. I need to place another order but I want to buy some snes chips but I want to make sure I have the right ones. I semi-goofed on the snes as well and thought those were 32 dip and most are 36 dip. I only bought 10 of those so they are still good for like dinosaur land. M27C801-100F1

The only 36 dip are tsop and requires a board. Buyic sells them mounted on a board but they are expensive. FUJITSU MBM29F033C-90PTN -TSOP Adapter III $12 each. I don't even know if you can buy the boards separate as I don't even know what they are called.

In this day and age I see no reason to any longer keep rare games when repros are so good. They look and play the same. I plan on selling my rare originals and making repros of them all. I still like the look of the games on a shelf so that's why I want to do it.


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PostPosted: Fri May 15, 2015 9:19 pm 
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Quote:
I semi-goofed on the snes as well and thought those were 32 dip and most are 36 dip. I only bought 10 of those so they are still good for like dinosaur land. M27C801-100F1

I looked at about 4 of my regular non-enhancement chip (except DSP 1) games and there were 23 pins, unless pins on the other side count as well, which in that case would be 46. I looked at 2 enhancement chip games I have, and there were 8 extra pins, 4 on each side, so there are 31, or 62 pins counting both sides. I actually don't have much, if not any, experience here so I won't really be able to help, unfortunately.

Just so you know though, we're prety civilized here. Most of us don't bite. :) (I did realize that I sounded like a bit of a jerk my first post here though.)


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