emulating chip parameters

laserbeak43 · 14 Jan 2005

had to edit the diagram there

also, the chhip has 3 tone generators and a noise generator.

each tone generator consists of a frequency synthesis section and an attenuation section.

i wasnt sure what the attenuator was so i went to dictionary.com and found this - # Electronics. To reduce (the amplitude of an electrical signal) with little or no distortion.

so i'm guessing that the attenuation section is the volume control?

-edit-

this makes a little sense to me.

"the frequency synthesis section requires 10 bits of info (F0 - F9) to define half the period of the desired frequency (n). F0 is the most significant bit and F9 is the least. This information is loaded into a 10 stage tone counter, wich is decremented at a N/16 rate where N is te input clock frequency. When the tone counter decrements to zero, a borrow signal is produced. This borrow signal toggles the frequency flip flop and also reloads the ttone counter.Thus, the period of the desired frequency is twice the value of the period register."(forgive my typing the datashet was in jpg format 🙂)

the frequncy can be calculated by the following: N f= ___ 32n

where N = ref clock in Hz n = 10 bit binary number

is this the sequencer?

stefan · 15 Jan 2005

Uhm. Exactly what are you trying to achieve here? To emulate an IC you'd have to know what it looks like on the inside, not just how to communicate with it.

laserbeak43 · 15 Jan 2005

well i've got plenty of pictures and schematics but it doesnt say anything about the sound quality or anything the only thing it says is that it has 3 tone gens and a noise gen.

all the rest looks like that electronics language little symbols and stuff. i dunno how this willl tell me what the chip does nd how it does it will it? but it's the official datasheet am i missing something?

stefan · 15 Jan 2005

But what is it that you want to achieve here? Why are you even trying to implement this specific chip in synthmaker when you probably could make something with the very same functionality but much easier and even better?

laserbeak43 · 15 Jan 2005

stefancrs wrote: But what is it that you want to achieve here? Why are you even trying to implement this specific chip in synthmaker when you probably could make something with the very same functionality but much easier and even better?

it's a chip from the sega master system. i want to emulate it. nothing more. but i cant seem how to figure out how to. i plan on making it better but i want to "MASTER THE CHIP" first 🙂

i'm totaly lost but i'd love to learn how to do it. makes me wat to se if i can find a class on assembler this coming semester

stefan · 16 Jan 2005

laserbeak43 wrote: stefancrs wrote: But what is it that you want to achieve here? Why are you even trying to implement this specific chip in synthmaker when you probably could make something with the very same functionality but much easier and even better?

it's a chip from the sega master system. i want to emulate it. nothing more. but i cant seem how to figure out how to. i plan on making it better but i want to "MASTER THE CHIP" first 🙂

i'm totaly lost but i'd love to learn how to do it. makes me wat to se if i can find a class on assembler this coming semester

do you really have the schematics for the "inside" of the chip? getting schematics that shows you how to use the chip should not be a problem, but getting a schematic over the actual chip sounds harder.

laserbeak43 · 16 Jan 2005

i have both the chip was made by texas instruments and i have a datasheet by them and i have a manual from sega and i have some docs from other people but it all seems to be in asssembler or with allthose little electronics symbols

stefan · 16 Jan 2005

laserbeak43 wrote: i have both the chip was made by texas instruments and i have a datasheet by them and i have a manual from sega and i have some docs from other people but it all seems to be in asssembler or with allthose little electronics symbols

I don't mean to be mean or anything here, but before trying to emulate a somewhat advanced Integrated Circuit (IC) you might want to learn some electronics and dsp, because it's not basic stuff (emulations of IC's). It's in a way more basic to build something like z3ta+ in synthmaker than to learn how to emulate IC's.

A datasheet does not give you any info on how to emulate the chip, and I seriously doubt that the sega manual do. These informations might give you info that somehow is sufficient for simulating the chip, but you already have that anyway (3osc etc).

laserbeak43 · 16 Jan 2005

youre mean!!! j/k lol i'm glad you told me that cause i dont know anything about ICs and the guy who pointed me to the data sheets must have mis understod my question then. i guess what i need to do is find out the bitrates and sample rates outputs then...

stefan · 16 Jan 2005

What will you do with that information? 🙂

laserbeak43 · 16 Jan 2005

well it's an 8bit videogame system so i dont want it to sound like a moder high quality synth..

jorge · 17 Jan 2005

does the chip you're trying to emulate have a name/number so I could google it? is there a reason you're trying to emulate it? is it an assignment or just an interest? do you intend to use the emulation to produce some sound? to make some music?

laserbeak43 · 17 Jan 2005

jorge wrote: does the chip you're trying to emulate have a name/number so I could google it? is there a reason you're trying to emulate it? is it an assignment or just an interest? do you intend to use the emulation to produce some sound? to make some music?

yea its in plenty of systems like the sega master system and coleco vision i have plenty of dos on it that i have downloaded SN76489 is the name of the chip. ive always wanted to make my own version of it to make music with along with a whole bunch of others. for years. but i didnt know where to turn ive asked thousands of developers those who make emus and things like that no one has been able to help or wanted to... ive read hundreds of docs over the years but none of em have been able to tell me what i wanted to know .

so i think its just me and i need to go to school to learn how to use these chips dunno... but yea i've wanted to emulate and manipulate these chips for years

here's a zip of my sga docs for genesis(megadrive) and master system about 10 megabytes http://www.simbiotrecords.com/segadocs.rar

jorge · 17 Jan 2005

here is a simple version of a synth that generates three square waves each with a frequency which is a result of the main frequency multiplied by a float and each with separate amplitude/attenuation.

and here is the schematic: [old link]

laserbeak43 · 17 Jan 2005

cool was working on it but my comp started to act up. i'm gonna get a little rest and catch up with you in the morning. thanks for your patience later 🙂

stefan · 17 Jan 2005

laserbreak: a tip! If you just want to make something that sounds similar to and has the same restrictions as some soundchip, don't emulate, simulate! 🙂

laserbeak43 · 17 Jan 2005

stefancrs wrote: laserbreak: a tip! If you just want to make something that sounds similar to and has the same restrictions as some soundchip, don't emulate, simulate! 🙂

yea what you have been saying to me all day is becoming more and more clear. has been as the day progressed. i'll sleep on it and get back to you guys later thanks again.

still trying to find out the sampleratre of this chip. i doubt that it outputs more than 8 bits tho

oh and btw jorge thanks for the last schematic i have to change it tho so that each one receives data on a seperate channel.

stefan · 17 Jan 2005

laserbeak43 wrote: stefancrs wrote: laserbreak: a tip! If you just want to make something that sounds similar to and has the same restrictions as some soundchip, don't emulate, simulate! 🙂

yea what you have been saying to me all day is becoming more and more clear. has been as the day progressed. i'll sleep on it and get back to you guys later thanks again.

still trying to find out the sampleratre of this chip. i doubt that it outputs more than 8 bits tho

oh and btw jorge thanks for the last schematic i have to change it tho so that each one receives data on a seperate channel.

Don't forget that the chip might be analouge. I'll take a look at that rar-file you assembled.

stefan · 17 Jan 2005

w00t? it's an ym chip.

http://www.kvraudio.com/get/1420.html

It does not simulate the 2413, but the 2149. Might be of interest for you to look at.

But the YM-chips aren't as basic as for instance the sid chip, because they are using FM synthesis.

stefan · 17 Jan 2005

For what it's worth, it's quite easy to make a synth with the same features / limitations etc.

It's actually not FM (frequency modulation), but PM (phase modulation), which is much easier to make a good implementation of.

I'd say that bitrate and sampling frequency is information of little interest when trying to simulate this chip. According to the docs, the DAC works in 9bit.

These guys have source code for emulation of the chip (written in C) if I understood their homepage correctly 🙂 http://fms.komkon.org/EMUL8/

laserbeak43 · 17 Jan 2005

stefancrs wrote: w00t? it's an ym chip.

http://www.kvraudio.com/get/1420.html

It does not simulate the 2413, but the 2149. Might be of interest for you to look at.

But the YM-chips aren't as basic as for instance the sid chip, because they are using FM synthesis.

yea although that chip only featured in japanese and european/uk versions i will emulate that at somepoin too. i dunno what it sounds like so i would have to find some roms or music to audition the fm synthesis.

laserbeak43 · 17 Jan 2005

stefancrs wrote: For what it's worth, it's quite easy to make a synth with the same features / limitations etc.

It's actually not FM (frequency modulation), but PM (phase modulation), which is much easier to make a good implementation of.

I'd say that bitrate and sampling frequency is information of little interest when trying to simulate this chip. According to the docs, the DAC works in 9bit.

These guys have source code for emulation of the chip (written in C) if I understood their homepage correctly 🙂 http://fms.komkon.org/EMUL8/

im fairly familiar with fm synthesis not so sure about pm tho altho i think i have played with alot of pm vstis, its just that i'm not sure sicnee there's so many different styles but it used alot of pwm with sub oscs and stufff

yes that website is the guy that lives 15 minutes from me that i had emailed. what on that site do you suggest i look at? i dunno much about c wich would prolly help my alot iff i did.

laserbeak43 · 17 Jan 2005

cool it emulates a chip? sweet but i prolly wont be able to use it welll in fl studio. fl doesnt mix well with se plugins. fl is my fav app to work/ audition samples in. i only open up cubase when i have to mix or record from my outbard synth

stefan · 17 Jan 2005

The source code was to be used in emulators (when writing a mame, sega or whatever emulator that is. to run games.) not to be used as a vsti 🙂

PM basicly is what most people call FM. DX7 for instance is a PM synth. Most are, especially the digital ones.

laserbeak43 · 17 Jan 2005

oh then im fairly fluent in pm synthesis 🙂

laserbeak43 · 17 Jan 2005

stefancrs wrote: Don't forget that the chip might be analouge. I'll take a look at that rar-file you assembled.

if it were analouge it woulddnt have a sample rate? the chip is connected to a videochip too

stefan · 17 Jan 2005

Oh, the ym chips aren't analogue, I wrote that before I looked at the papers.

laserbeak43 · 22 Jan 2005

i took such a break from it(for mines and you guys sakes 🙂 ) that i forgot where i was. but im back 🙂