newly made SB-clone ...with 24bit and AES/EBU... join in development!

Discussion about old sound cards, MIDI devices and sound related accessories.

newly made SB-clone ...with 24bit and AES/EBU... join in development!

Postby jxalex » 2018-9-16 @ 16:18

I thought to lay out my thoughts before starting. Someone might have done perhaps?

In the CS4231A chip the datasheet provides info which is enough to make a complete soundcard. HOwever I
came to another thought after reading it, that it can be developed even further!

What about a soundcard which matches the following criteria:
1. works under the DOS software
2. on the ISA bus,
2. 24 bit dac/adc, fullduplex, single/double DMA channels switchable. 32..96kHz
3. has SPDIF AES/EBU for both input and output in order to use also the 24..32 bit external converters, wordclock
4. BUT ALSO can emulate the SB16 by hardware when just during initialization switch some registers.
5. onboard MPEG decoder (imagine mp3 player on your 386 machine, so far the requirement for software processing atleast 80..100Mhz 486 for 256kbit stream !)


So far there is no such card or its software does not run under the DOS, nor does not emulate SB16..32..64.

The simplest way to start is just to have the playback and recording. All other necessities like mixer and such can be added later if someone wants, himself.
The MIDI port and all other things can we add later, but these are the things just to start on and simplest is just to start with wave playback and record.

It is meant for some serious recording and playback for studio, but can be a great if can be used as SB emulation too.

Well?
I can make the hardware part, and the programs which under the DOS use it, however
I need your help in order to have in hardware the SoundBlaster emulation capability too!
This becouse I am not familiar the card initialization procedure of these SoundBlaster cards in order to make it SB compatible. At first it will be done as a card to ISA bus which then interfaces the AES/EBU interfaces.

I think it IS possible to make a hardware clone which can behave like a SB card.
Those who have made some programming on the SB cards under the DOS, can you tell me...
* how much FIFO buffers these card use between the BUS and DAC?
* how the system initializes SB card and recognize its "answers" ?
* the sound with DMA transaction.
* how they start/stop sound buffers or initialize the sampling rates

It is also possible to make on PCI, however we already know how many incompatibility with SB it is, so it may be an option to those who may want to use the multitracking capability what is available with the PCI bus speed card model... ;-)

SO far I made some 8x8 port ISA-bus I/O card. So some hardware electronics has been done already.

If we just make the research and development here in a open way then we all just make it.
So, another reverse-engineering-upgrade project of the sound cards.
Tervitused p6hjamaalt! ;-)
Last edited by jxalex on 2018-9-16 @ 18:21, edited 1 time in total.
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Re: newly made SB-clone ...with 24bit and AES/EBU

Postby Jo22 » 2018-9-16 @ 17:29

I like the idea of 24-Bit and SPDIF, would be cool for Amiga trackers. :D
(If there's any FM chip to go on board, too, an OPL4 clone/FPGA with sample RAM would cool!)
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Re: newly made SB-clone ...with 24bit and AES/EBU

Postby jxalex » 2018-9-16 @ 17:40

yes.
does the amiga uses the single-transfer DMA or a block DMA?

still... how much FIFO buffers would be adequate ? how much is sitting on those SB cards?
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Re: newly made SB-clone ...with 24bit and AES/EBU... join in development!

Postby jxalex » 2018-9-16 @ 18:30

well, now I found THIS: https://pdos.csail.mit.edu/6.828/2008/r ... laster.pdf

it says some information, however the missing part is that when giving the commands about the sampling rates, and other commands, that what are the limits or values what the actual cards use.
Also, when using the autoinitialize-DMA, then what is the FIFO size on the cards and what are the values used?
So, some real hardware details are missing.

Searched for the Soundblaster developers kit programmers manual for this information, but without success.
The programmers heaven seems like have called off the dos sound programming files, however I miss them, or becouse of their new messy webpage I got lost, however it gave me zero results when I searched "soundblaster" or "Gravis" word on sound category. ;-)
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Re: newly made SB-clone ...with 24bit and AES/EBU... join in development!

Postby jxalex » 2018-9-16 @ 23:40

I searched some fifo chips.

320K x 8bit organization chip -
This is some FIFO chip however it is with some odd requirements -- the read operation must be after 128 write cycles and clocks must be atleast 1Mhz)
The other chips 1K/2K/4K/8K/16K x 9bit are more expensive (6USD chip), but from not from recommended sellers and uncertain if there are available enough of these if some other fellows want the soundcard too.

one schematic solution: with the FIFOs, and then the interrupt driving is with PIC and then the AES/EBU coder circuit.
Another solution is when the FIFOs are replaced with the SRAM buffer circuits (while to one memory chip the new data is written the another memory chip is read out). It is rather bulky but guaranteed the availability of the not so common chips and simpler to build the PCBs.


The third solution:
To make the card with 1-2 fast MCU based which interfaces the bus and SRAM and DACs. But then it should be
someone who could recommend that.
Some ramblings:

So far I did all things with simple logic chips when making the parallel to serial converter in order to add the 24bit sigma-delta DAC and AES/EBU output to a Roland D550 synthesizer, it consisted with 12 chips, but simple design. So I thought that why not to make with the same approach the soundcard too, becouse atleast there is no need for a expensive programmers or the latest programming environments for the MCU programming for this task.
Well... perhaps someone can find a way how a ISA bus interfacing circuit can be reduced to 5..6 chips from my initial schematic with 20 logic chips and 4 RAM chips, (and which is for playback only!). For fullduplex the amount of chips will be double.

which will be the parallel to serial converter chip capable of making the serial bit stream with 3Mbit/s ?
16c552 is up to 1Mbit

The CPU / MCU... which ones are possible to have the 16-bit I/O port to ISA bus, 8bit bus for SRAM and 8bit for DAC, or just to have several buffered I2S outputs and inputs? A bit newer 32bit Microchip PICs ? still here the help is needed
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Re: newly made SB-clone ...with 24bit and AES/EBU... join in development!

Postby jxalex » 2018-9-17 @ 00:02

PIC32MZ0512EFK144

hmmm...?

only if anyone of us can solder to a pcb this circuit. otherwise we need to seek something with smaller amount of pins and with wider spacing.

perhaps the

PIC32MZxxxx series ?
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Re: newly made SB-clone ...with 24bit and AES/EBU... join in development!

Postby Jo22 » 2018-9-17 @ 01:22

jxalex wrote:Searched for the Soundblaster developers kit programmers manual for this information, but without success.

Hi, did you check the Thunder Board Programmer's Reference, too ?
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Re: newly made SB-clone ...with 24bit and AES/EBU... join in development!

Postby jxalex » 2018-9-17 @ 10:21

Jo22 wrote:
jxalex wrote:Searched for the Soundblaster developers kit programmers manual for this information, but without success.

Hi, did you check the Thunder Board Programmer's Reference, too ?


yes. There is nothing said about the block sizes not even in the programming examples.

0. the hardware cards transfer buffer size, or if it has any buffers at all.
1. the size of the DMA blocks used for continuous dma transfer
(and if that DMA transfer is paused several times and in reality it is transferred one byte at a time.)

what is needed to know is that if just one byte buffer at the card is enough for DMA transfers or there should be 32...64kB FIFO, or shared in the blocks.

Well, thing is that sound transfer for 16bit DMA can be also with 32kB chunks, but it does not really make sense if the soundcard has just 1 byte buffer which means the excessive DMA transfer putting on hold.


[EDIT]
now I am getting somewhere: in a CS4231A datasheet (the DAC used on a Gravis Ultrasound MAX) this is the first place when I see some concrete numbers about hardware card -- this DAC uses 16 samples FIFO.
FYI the software in windows transfers the sound in 8192 byte chunks.

Now how are the numbers compared to SOundblaster 16 ASP or SOundblaster 32 and 64 cards... ?
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Re: newly made SB-clone ...with 24bit and AES/EBU... join in development!

Postby Jo22 » 2018-9-17 @ 12:33

What about third-party books made of paper ?
I once had a Sound Blaster book that described programming and such.

https://www.amazon.com/Ultimate-Sound-B ... 1565292987
https://www.amazon.com/Sound-Blaster-Bo ... 1557551812
https://www.amazon.de/gp/search?index=b ... 0078820007
https://www.pcgamer.com/author-of-sound ... -pc-audio/

They all seem to be pretty cheap - about $3 each. :)
if you're lucky your local library still has them (not thrown in the dumpster yet).
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Re: newly made SB-clone ...with 24bit and AES/EBU... join in development!

Postby jxalex » 2018-9-17 @ 13:03

well, it is more complicated. THe programming example says that the block size can be 32 or 64kB, depending on the 8 or 16 bit DMA transfer, but the examples say nothing about the hardware.

what I need to know is this: how big FIFO buffer chip I should use in my schematic design when making a clone soundcard!
Also, what is the maximum DMA transfer burst size for ISA bus?
That determines the FIFO bufer size.

in my local library, and neither in the state library there are not such books.

by the way, what are the other DAC chips the SB cards use?
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Re: newly made SB-clone ...with 24bit and AES/EBU... join in development!

Postby Jo22 » 2018-9-17 @ 14:43

The Sound Blaster 1.x series had a MC1408 D/A converter, I believe.
Datasheet is available here.

The Sound Blaster DSP was just a simple microcontroller. 8051 or similar, I believe.
http://www.os2museum.com/wp/sound-blaster-the-french-connection/

Edit: Also interesting: https://ancientelectronics.wordpress.com/tag/sound-blaster-1-5/
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Re: newly made SB-clone ...with 24bit and AES/EBU... join in development!

Postby jxalex » 2018-9-17 @ 15:04

reading the ISA bus architecture, and "The undocumented PC"

well... the DMA max transfer capacity is 2MB/s in a 16bit mode,
the memory refresh is after every 15 uS, thus the DMA must pause its operation for a moment?

with speed where system allows lousier refresh (anything in pentiums?) then in a 32 microseconds it transfers - 64bytes total, thus 32 bytes for a low and 32 bytes for a high bus fifo would be enough with such systems.

or how?
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Re: newly made SB-clone ...with 24bit and AES/EBU... join in development!

Postby jxalex » 2018-9-17 @ 17:01

after some research I thought to go for a some simpler solution.

the cypress supplied some fifo memories ranging from 64 to 4096 x9 size.
64x9 and 512x9 are the ones which are available through feebay, so, choosing the 512 for experiment would be generous enough.
price $1.5/pcs. Using 4 of them (2 for record and 2 for playback buffer, in order to use as double buffer DMA).

CS8401...6 as TX and , CS8414...16 as RX chips for AES/EBU/SPDIF.
one of each, price varying from $1.5.. $3.5

also 4 of the 74 LS/HC/AC/ACT 245 are used.

Adress decoding circuits ( K155ID7 / 74HC138 / 74 LS138 )

The next ones are the microCPU which is controlling all of it. PIC16F870 should be enough for this perhaps to catch and send the DMA request signals?
Then perhaps soon the card with digital input/output would be ready, which is estimated to work with ca 96kHz 24bit, but can also emulate the soundblaster.

at first the playback, then the record side should be added to schematic.
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Re: newly made SB-clone ...with 24bit and AES/EBU... join in development!

Postby jxalex » 2018-9-17 @ 17:41

for a wide sample rate compatibility for playback the AK4125 / SRC4192 and other sample rate converters can be used.

will be optional as it does not affect the main schematic design which can handle everything from 32kHz.
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