Connecting a AY-3-8910 for a ZX Spectrum 128k clone

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alcid34
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Connecting a AY-3-8910 for a ZX Spectrum 128k clone

Post by alcid34 »

So I made a Harlequin 128k (a timing compatible ZX Spectrum 128K clone) that currently has an AY-3-8912 installed. I was wondering if it is possible to directly connect an AY-3-8910 instead since it is the exact same chip, just with 40 pins (plus I have many on hand). So I created a daughterboard (pictured below) to attempt to connect it directly to the respective pins.

However, when I tested it with a demo, all I get is nothing but static noises. Pretty sure I connected it right by checking both datasheets and their respective pins. Can anyone help me what I did wrong?
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McKlaud
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Re: Connecting a AY-3-8910 for a ZX Spectrum 128k clone

Post by McKlaud »

Any AY-3-891x can work with ZX Spectrum (sound wise). In my applications I use 8910s, their clones and 8912s without any issues, as log as chips are fine. There is something wrong in your connections. Any schematic would be helpful.
Claudius
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Moggy
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Re: Connecting a AY-3-8910 for a ZX Spectrum 128k clone

Post by Moggy »

McKlaud wrote:
Thu Nov 28, 2019 12:39 pm
Any AY-3-891x can work with ZX Spectrum (sound wise). In my applications I use 8910s, their clones and 8912s without any issues, as log as chips are fine. There is something wrong in your connections. Any schematic would be helpful.
I agree with Mcklaud. I use this chip with my ZX81 AY/turbo setups as I prefer (to my musicians ears at least) the slightly more grunty sound they have and if your wiring/pin-outs are correct and the chips are not duff then they should work.

It is also possible you posses some of the chips described below.
A paragraph from the chips wiki page may prove helpful...

https://en.wikipedia.org/wiki/General_I ... _AY-3-8910

"Although there are only 16 registers, the four MSB bits of the 8-bit bus must be set to the factory default '0000' value when selecting a register. Incorrectly setting the MSB bits causes the chip to ignore the register change. General Instruments did take orders for customized MSB bits (factory set to other than '0000'). The chips made with customize-set MSB register bits allow the same processor to control more than one AY chip on the same bus (e.g. Mockingboard sound card for Apple or TurboSound for ZX Spectrum). There are many new-old-stock (NOS) chips on the secondary market with MSB bits factory set to a non-'0000' value. The non-0000 value can cause significant developmental troubles for designers and repair technicians. Software must be written to identify the correct value of the MSB bits on any given chip. Also, software must be changed or hardware added to allow these factory set MSB chips to be used in place of the default '0000' chips. "

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1024MAK
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Re: Connecting a AY-3-8910 for a ZX Spectrum 128k clone

Post by 1024MAK »

The AY-3-8910, AY-3-8912 and AY-3-8913 internally all use the same silicon die (chip). The only difference is which die connections are brought out on to the carrier DIL package.

So the AY-3-8910 has two general-purpose 8-bit parallel I/O ports, A and B, and is in a 40-pin DIL package.
The AY-3-8912 is the same chip in a 28-pin package, with parallel port B simply not connected to any pins.
The AY-3-8913 is the same chip in a 24-pin package, with both parallel ports not connected.
Also some of the test terminals are not brought out onto any pins for the later two.

There are no differences to the sound generator section.

Remember, the The AY-3-8910 /2 /3 were part of a range of chips (or chip set) designed to work with the microprocessor that was originally also part of the range (but was dropped due to the popularity of the Z80 and 6502).

Mark

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XavSnap
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Re: Connecting a AY-3-8910 for a ZX Spectrum 128k clone

Post by XavSnap »

Ay.JPG
Xavier

McKlaud
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Re: Connecting a AY-3-8910 for a ZX Spectrum 128k clone

Post by McKlaud »

Have you connected A9 of AY-3-8910 to GND?
Claudius
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XavSnap
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Re: Connecting a AY-3-8910 for a ZX Spectrum 128k clone

Post by XavSnap »

Hi,
A RadioPlan issue #425 exemple from Patrick Gueulle.
RadioPlan.JPG
Xavier

alcid34
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Re: Connecting a AY-3-8910 for a ZX Spectrum 128k clone

Post by alcid34 »

McKlaud wrote:
Thu Nov 28, 2019 6:42 pm
Have you connected A9 of AY-3-8910 to GND?
Did that and still outputting static...

alcid34
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Re: Connecting a AY-3-8910 for a ZX Spectrum 128k clone

Post by alcid34 »

For anyone interested in the schematic in the hopes of solving my problem, I'm opening up the EasyEDA project file that I used to create my daughterboard: https://easyeda.com/flakyfan101/ay-3-89 ... ghterboard

Moggy
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Re: Connecting a AY-3-8910 for a ZX Spectrum 128k clone

Post by Moggy »

Have you even considered that your stock of chips could be duff, or that they may be as described in the wiki article or are you dismissing this completely ?

I only ask because if you are are confident in your d/board being correct then I cannot see what could be the problem other than what as been stated already.

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