General Instruments AY-3-8910 Sound Chip Which Sound Chip gets used for the enhanced MSX compatible audio in the CV-NUC+MSX Module?
When this project first started out it was going to be the General Instruments/Microchip AY-3-8910 which was originally created by a company called General Instruments in 1978.
It was widely used in arcade machines in the early 80's, and was also integrated into the MSX and ZX Spectrum home computers. And two of the size reduced versions made their way into the Mockingboard for Apple II computers.
Later in 1987 General Instruments spun off a new company called Microchip Technology which started producing the chip for a couple more years under its brand name, so it's common to see the chip with either GI or Microchip markings.
Around the mid 80's, it became available from Yamaha as the YM2149F under a license agreement with General Instruments. Although Yamaha made a few changes, one being a selectable clock divider which could allow it to operate from a 4 Mhz system clock, and they also added additional resolution in the internal volume envelope tables. This last part plays a roll in our decision of which chip to use.
When this project first started out it was going to be the General Instruments/Microchip AY-3-8910 which was originally created by a company called General Instruments in 1978.
It was widely used in arcade machines in the early 80's, and was also integrated into the MSX and ZX Spectrum home computers. And two of the size reduced versions made their way into the Mockingboard for Apple II computers.
Later in 1987 General Instruments spun off a new company called Microchip Technology which started producing the chip for a couple more years under its brand name, so it's common to see the chip with either GI or Microchip markings.
Around the mid 80's, it became available from Yamaha as the YM2149F under a license agreement with General Instruments. Although Yamaha made a few changes, one being a selectable clock divider which could allow it to operate from a 4 Mhz system clock, and they also added additional resolution in the internal volume envelope tables. This last part plays a roll in our decision of which chip to use.
Yamaha YM2149F Sound Chip Probably due to the Atari ST and MSX2 computers using the YM2149F chip as their main sound chip, as well as being the last such chip that was still in production in the early 90's, there appears to be quite a large supply of these being sold on the surplus market. Whereas the AY-3-8910 is in extremely short supply, and is often counterfeited, using a remarked YM2149F in its place (referenced in Part 4).
Because that counterfeiting is so common place, you are more likely to get a remarked YM2149F instead of an AY-3-8910 when purchasing the AY chip. And this is important since there will be a marked difference in how 'hot' the audio output will be when compared, with the AY chip being louder out of the gate due to the lower resolution audio control when interfaced as an AY chip.
So a decision was made to spec the CV-NUC+MSX Module's 2nd sound chip as the Yamaha YM2149F since 9 times out of 10 that is indeed what you will get when purchasing from the surplus market (there are arcade parts suppliers that still carry genuine AY chips, but you'll pay quite a bit to get one). Sticking with the YM chip will insure consistent audio output utilizing the same audio processing circuit, with no need to have any configuration adjustments. And it also consumes half the power as compared to the AY-3-8910.
So on all CV-NUC+MSX production boards only the YM2149F will be marked on the silk screen as seen below. And this is the chip that should be purchased, which appears to be available from utsource at a reasonable price.
Because that counterfeiting is so common place, you are more likely to get a remarked YM2149F instead of an AY-3-8910 when purchasing the AY chip. And this is important since there will be a marked difference in how 'hot' the audio output will be when compared, with the AY chip being louder out of the gate due to the lower resolution audio control when interfaced as an AY chip.
So a decision was made to spec the CV-NUC+MSX Module's 2nd sound chip as the Yamaha YM2149F since 9 times out of 10 that is indeed what you will get when purchasing from the surplus market (there are arcade parts suppliers that still carry genuine AY chips, but you'll pay quite a bit to get one). Sticking with the YM chip will insure consistent audio output utilizing the same audio processing circuit, with no need to have any configuration adjustments. And it also consumes half the power as compared to the AY-3-8910.
So on all CV-NUC+MSX production boards only the YM2149F will be marked on the silk screen as seen below. And this is the chip that should be purchased, which appears to be available from utsource at a reasonable price.
- Michael
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