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Posted By: plgDavid Epoch Cassette Vision and uPD77X chips - 10/19/15 03:52 PM
SlyDC just updated his blog with a bit more info:

He's traced the pins of the NEC all in one micro, (thanks!)
Awesome! laugh
PlgDavid: can you ask slydc to flip the pcb over in this pic: http://1.bp.blogspot.com/-S0V0h08qeQ8/ViRDlpe0uPI/AAAAAAAAASc/NLHVDKUgaCw/s1600/battle%2Bvader.jpg and take a picture of the back?

The 'two missile pins' and 'two start pins' thing is confusing. Are they shorted together when the button is pushed?

Posted By: plgDavid Re: Epoch Cassette Vision and uPD77X chips - 10/19/15 05:13 PM
No need here are scans of mine (after removing the chip)

Posted By: plgDavid Re: Epoch Cassette Vision and uPD77X chips - 10/19/15 05:17 PM
And the Cassette Vision JR PCB scan

Posted By: plgDavid Re: Epoch Cassette Vision and uPD77X chips - 10/19/15 05:19 PM
Full album here
My Cassette VIsion pictures
On the cartridge:
capacitor C01, I see one leg connects to upd pin 18; where does the other leg go?
Also what are the markings on capacitors C01 thru C04?
Also is resistor R02 5.6K or 5.7K? the stripe is poorly visible.
Also are there any markings on R04 to show what value/type of resistor pack it is?

Here's my hacked together diagram so far of the pinout:

Posted By: plgDavid Re: Epoch Cassette Vision and uPD77X chips - 10/19/15 09:47 PM
C01 1uF 50v (neg terminal goes to ground)
C02 10uF 16v
C03 1200pF (122)
C04 47nF (473)
R02 is green brown red gold (hence 5.1k Ohms 5%)
R04 7X682M
Updated, thanks!
More info from SlyDC:

Thank you, SlyDC!
Posted By: F1ReB4LL Re: Epoch Cassette Vision and uPD77X chips - 12/18/15 03:52 PM
http://www.ebay.com/itm/TV-Baseball-/311505438633?hash=item48872bc7a9 -- is it some Cassete Vision-based standalone game? or something unique?
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 12/18/15 10:36 PM
TV Baseball was released as a standalone game before Cassete Vision even existed. It was then re-released as a CV cart (Cart #2), I believe it's the exact same game, but there could be some slight changes I guess.
Posted By: Sly DC Re: Epoch Cassette Vision and uPD77X chips - 01/12/16 11:23 PM
Yes, both the "TV Baseball" and "Baseball" cartridge are the same game, also same for the "TV Vader" and "Battle Vader" cartridge (same chips).

If plgDavid is up to it, i can lend him soon all the cartridges as i'm waiting for the "Elevator Panic" cartridge to arrive so i'll have the entire library ready to be dumped.

Same as for the Hanimex HMG-7900, i'm waiting for the last game (Raging Turtles) to arrive soon and i'll have also the entire library for this game system.

Oh and almost forgot, i can also lend the "Epoch TV Vader" as this one is completely dead so no problem to "cut in half" the chip or give it hell! (lol!)
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 01/13/16 09:13 AM
Nice, I guess he won't be needing my games after all smile
I'm really looking forward to see if any progress can be done on these, I think the HMG-7900 carts will be easier to dump than the CV ones at least judging by the ones I looked inside, not really sure about what's inside each cart since it seems to vary a lot more than in the CV.

I think plgDavid can't dump CV carts as he seems to have sent one to LN a while back. Hopefully someone will be able to figure a way to dump these in a non-destructive way, for most games of the system this isn't a big deal though since they are pretty common.

Dumping the TV Vader would also be interesting, I was actually considering buying that TV Baseball which sold cheap, but ended not being around at the time the auction ended.
This isn't a rare game anyway, so there will be plenty of chances to get one if we need it.
Posted By: plgDavid Re: Epoch Cassette Vision and uPD77X chips - 01/13/16 04:59 PM
I'm waiting for one of them to be decapped (the one I sent to LN), then we might find out a way to do the others without such invasive measures.
I'm trying to get the package sent to sean but having trouble finding the scv and s&l boards. I think I know where they are now, though.

Edit: nope. not there. I'm driving myself up the wall looking for them, I think I will have to send this package without them.

Edit2: package sent.

Posted By: Sly DC Re: Epoch Cassette Vision and uPD77X chips - 01/13/16 05:19 PM
@ssj: But before lending him the games, i'm still waiting for the last one to arrive and in the meantime, i'll A/V mod one of the game system and record videos for each game.

The difference between the HMG-7900 and the Cassette Vision is that the Cassette Vision uses "all-in-one" chips or aka dedicated chips with built-in program and for the HMG-7900, the D779C-300 is
also a "all-in-one" chip but can change the built-in program (in this case, the Chaser game) with other program cartridges. smile

So simply put, a Cassette Vision cartridge has a "all-in-one" dedicated chip and a HMG-7900 cartridge has only a PROM chip.
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 01/13/16 08:59 PM
Well if Sean is interested on decapping one CV board some games are pretty cheap on ebay, there are a couple available for less than $10. I'll happily pay for one of those if needed since that board seems to be MIA.

I believe previous attempts have been done to dump CV games electronically without success, but there has been a lot of progress done lately with the electronic handhelds dumping so perhaps someone will manage to figure it out.
Posted By: starlord Re: Epoch Cassette Vision and uPD77X chips - 01/14/16 10:01 AM
Great job slyDC, that is greatly impressive that you managed to secure all the hanimex library... Actually, do you have all the soundic compatible console games (I believe there were 3, including the hanimex, one from soundic and one from lansay)... Do those last 2 systems have games which are unique or Are they all part of the hanimex library?
Posted By: Sly DC Re: Epoch Cassette Vision and uPD77X chips - 01/16/16 04:35 PM
@ssj: There is a Baseball cartridge on Ebay for 8$ and the seller is in the US: http://www.ebay.com/itm/Epoch-cassette-vision-baseball-US-seller-/161931329940?hash=item25b3dc0194:g:gY4AAOSw-vlVhd1j

This is the cheapest ECV cart i've seen so far. Well someone will surely discover a way to dump one of these "all-in-1" chips and those NEC uPD774C to uPD779C have a program section inside the chips, which i'm assuming 1K or 2K (NEC uPD770C is only a All-in-1 Pong chip used in the Epoch System 10 & 10M2 + the Toshiba TVG-610).

@starlord: Thanks! Well i'm not the only one who has a complete HMG-7900 library and i should be getting the last game this week.
I only have the Hanimex HMG-7900 and the Soundic Programmable Colour Video Game SD-290 so if i want all models, i'm missing the SD-270 (Rollet Videocolor). And there is no unique game titles in their respective library as they use all the same games and they are fully compatible which each others.

I listed all the HMG-7900 clones on the LOVEM.E.S.S. blog but i forgot to mention which model-types they belong to. I'll post a picture with all the model-types very soon.
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 01/17/16 02:15 AM
Originally Posted By Sly DC
@ssj: There is a Baseball cartridge on Ebay for 8$ and the seller is in the US: http://www.ebay.com/itm/Epoch-cassette-vision-baseball-US-seller-/161931329940?hash=item25b3dc0194:g:gY4AAOSw-vlVhd1j

Yeah I know of that one, I'm not in the US and the guy is asking insane shipping costs for outside US. If anyone wants to pick it up and try to dump it I'll gladly pay for it as I said though.
Posted By: plgDavid Re: Epoch Cassette Vision and uPD77X chips - 01/18/16 03:19 PM
Originally Posted By ssj

Yeah I know of that one, I'm not in the US and the guy is asking insane shipping costs for outside US. If anyone wants to pick it up and try to dump it I'll gladly pay for it as I said though.

Just bought it.. urhg 35CAD.
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 01/18/16 08:20 PM
Ouch I was hoping someone in the US would pick it up as it would be way cheaper, the shipping costs he was asking were ridiculous.
Posted By: Sly DC Re: Epoch Cassette Vision and uPD77X chips - 01/19/16 12:52 AM
You shouldn't have brought it plgDavid because i can lend you my carts or i can sell you some doubles i have. SSJ is right, shipping cost outside a country is now very ridiculous, i would even say outrageous sometimes (importing/exporting).

The only thing is that i can't bring the stuff to your house as my car has a transmission problem since the beginning of this year, so it's under a pile of snow (looks like an igloo...lol!!).
Posted By: plgDavid Re: Epoch Cassette Vision and uPD77X chips - 01/19/16 01:49 AM
No worry Sly DC. I'm a compulsive crap buyer.
Just hope the decap can give us a clue on how to dump them.
Sly_DC: I saw this linked from twitter: http://discreteconsoles.blogspot.ca/2015/11/hanimex-hmg-7900-cartridge-pcb-scans.html
and I believe the Motorola chips in those carts are MC6805(or less likely MC6804 which has the same pinout) mask MCU parts. They should all be dumpable, I don't think the mask MC6805 can be protected at all. It is a bit awkward to dump though.

Posted By: plgDavid Re: Epoch Cassette Vision and uPD77X chips - 01/18/18 02:02 AM
Hi Lord Nightmare!

Sorry for the necro bump, but was wondering where my uPD77x chip I gave you is at and it it was decapped?
He sent me a upD777C-009 about 2 years ago- I bet that's it. I decapped it and made a top metal die shot: www.seanriddle.com/d777_metal.jpg I don't think I ever removed the top metal layer. I've got a better microscope now, so I can clean the die in acid and take another set of top metal pics, then whink it to remove the top metal layer. I can see bits in the ROM, and they'll have more contrast when I remove the top metal layer. I've decapped a few NEC chips and matched visual ROM dumps to Kevtris's electronic ROM dumps, so I might be able to make a visual dump of this one.
Posted By: plgDavid Re: Epoch Cassette Vision and uPD77X chips - 01/18/18 02:21 PM
Awesome update, thanks. When you mean matching Kevtris's ROM dumps, that was for which type of chips? if its upD77X, given the procedure I could dump the rest of my cartridges.
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 01/18/18 07:02 PM
Sean, did you ever check with Kevin if he is able to dump these electronically? I recall checking with him a few years back and iirc he hadn't tried it by then.

I recently sent a Hanimex HMG7900 machine and some games to PeT so he could have a look at it and the machine chip is from the same family (upD779C).

ECV games aren't particularly expensive so even if the dumping process ends up being destructive wouldn't be a big deal I think, I'd love to see this one emulated that's for sure. ECV, HMG-7900 and Gakken TV Boy are some tough nuts to crack.
Turns out I had already Whinked the chip, so I took pics with the top metal removed. I also re-composited the top metal pics and created a larger die shot: https://seanriddledecap.blogspot.com/2018/01/blog-post.html

plgDavid- I decapped chips from some games that Kevtris had already electronically dumped so that I could figure out the physical location of the ROM bits. I used that information to visually dump Fabulous Fred's D557 and Computer Gin's D650. So I was hopeful that the ROM layout was the same in the D77x.

ssj- Not recently. A couple of years ago I sent him a Cassette Vision D777 that incog had sent to me.
Unfortunately the D777 ROM is unlike any of the other NEC chips I've decapped. There are actually 2 ROM areas: a smaller one at top center with 50 rows of 114 bits, and a larger one across the bottom of the die with 64 rows of 360 bits. The smaller one has 7 columns of 16 bits and one column of 2 bits. The larger one has 24 columns alternating between 14 and 16 bits.

I transcribed both of them visually:
www.seanriddle.com/d777_1_raw.bin for the smaller one and

www.seanriddle.com/d777_2_raw.bin for the larger one.

Since 114 isn't divisible by 8, the first file has 50x15 bytes; each row has 6 bits of padding added to the end. I also rotated the 1st ROM array 180 degrees before transcribing so that the address decoding for the 2 ROM areas had the same orientation.

Because I dumped these visually, there are likely a few errors, so please double-check them
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 02/13/18 09:13 AM
Anyone managed to figure something out of the dumps?
The D777 is an all-in-one micro iirc as the console board doesn't have any video or audio hardware so maybe that would explain the 2 ROM areas.
Posted By: plgDavid Re: Epoch Cassette Vision and uPD77X chips - 02/13/18 02:29 PM
Hey Thanks Sean!
I just noticed this topic was updated.
Wow, that is some serious puzzle.
@ssj: for HMG7900-SD204 I think I sent you a dump of the 8049 2 years ago (this cartridge is based on a software "dumpable" 8049 clone).
but there may be a part of the 779 used for graphics or sound.
Posted By: incog Re: Epoch Cassette Vision and uPD77X chips - 02/26/18 01:44 PM
Is that from the early TV-Game, which also uses this chip, Epoch Space Invaders?
SD204 is https://www.youtube.com/watch?v=l82RbXcq6qA "racing turtle"... it's not a very great game and fixed volume speaker (preset to "loud") is awfull. This console is probably the lowest level of fun of all my collection. SD203 is a bit close to Epoch Space invader but in a reduced version (no shields)
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 02/27/18 12:39 AM
I recently sent the HMG 7900 console and some games to PeT to see if he could make something out of it, but he wasn't able to make any progress on it. Kevtris was interested to look at it at some point, but then got too busy. I think Sean will probably be able to dump the Motorolla micros based on what I spoke with him a couple years back, but without the 779 they won't be of much use.

Yes, I believe the 8049 will use the graphics and video from the 779 and iirc SlyDC came to that conclusion when he was reverse engineering the Cassette Vision and the HMG 7900. I think all the A/V stuff is done in the 779. Either way if someone figures out to emulate the Cassette Vision I'm sure HMG 7900 will likely be possible to emulate too.

I made that dump public back then, but don't think it ever got added to the softlists probably because there is no driver for the system.
I'm not sure the 779 as enough pins to be something really complex when the 8049 is used and the 8049 is probably almost a complete game in a microcontroler.
a very partial pinout of the 779 is (when working with the void cartridge SD201)

| U |
----| 1 42 |---- Clock 4MHz
----| 2 41 |---- VCC 5.6V
----| 3 40 |----
----| 4 39 |----
----| 5 38 |----
----| 6 37 |---- ? out video 50hz
----| 7 36 |---- ? out video 50hz
----| 8 35 |---- ? out video 50hz
----| 9 34 |---- ? out video 50hz
----|10 33 |----
out video 15khz ----|11 32 |----
----|12 31 |----
out video 15khz ----|13 30 |----
out video 15khz ----|14 29 |----
out video 15khz ----|15 28 |----
out video 15khz ----|16 27 |----
out video 15khz ----|17 26 |----
out video 15khz ----|18 25 |----
----|19 24 |----
----|20 23 |----
GND ----|21 22 |----

But now that I have a logic analyser I can make a bit more advanced search. I do not have the 8049 cartridge but I have a motorola (SD203) that is probably also an almost one chip game.
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 02/28/18 01:34 AM
I still think all the A/V stuff is done by the 779 and the carts only hold the game rom, PeT also seem to agree with this when he was having a look at trying to get the SD-204 dump running. From his investigations he told me:
"When it is really a 8041/MCS48 variant then the cpu core is already emulated in MAME.
The console schematics might be needed for proper understanding of the hardware for emulation.
Started emulation, but it doesn't have something like video memory.
Instead it transmits high level commands over the bus and the D779C does some rendering."
It think that putting some logic analyser will tell more.
My guess (but only an hypothesis for now) is that all cartridges have an MCU that takes hand controller as an input (the void SD201 cartridge is a switch to bring hand controls to the 779, and probably also another switch to discard internal game).
I do not think the system has much video memory, graphics may be generated on the fly by mcu in sync with CRT like atari VCS.
I have the console and SD203, as soon as I will reinstall my crapy logic analyser I will do some tests (in the next days I think).
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 02/28/18 09:17 AM
Yes, it would be nice if you could test that and try to find out for sure. SlyDC already made some progress on this, but not sure how far he went he never got back to the last email I sent him about the subject.
I can confirm that all connections from both hand controllers go to the cartridge connector. Also uPD779 does video and sound generation (at least for SD203 and all cartridges based on the same PCB). There is a direct connection between uPD779 and the MCU on the cartridge, there are 6 bits from cartridge MCU to uPD779 (throw an hex buffer 14050). I did not check the direction,
A great number of the uPD779 pins are unconnected.

Unfortunately I fried the SD203 MCU while connecting the ground of the logic analyser so I will need to find another cartridge (It's common and still cheap here).
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 03/02/18 02:17 AM
Nice, it is as suspected then. I'm sure it will work like that for all carts. Don't forget that SD-205 uses the paddle so some of those pins might be used for the paddle controller.
Too bad you fried the SD-203, there's actually another copy for sale on ebay right now, but I suppose you can get it much cheaper there.
the potentiometer from controller also goes to the cartridge port, in SD205 a HEF4069 hex inverter is probably used as an oscillator that is read by the MCU.
I should receive next week another console + SD203 + SD201 + SD208. I now know where I should put the analyser (and my 8chanel will be enough for the task)
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 03/02/18 09:19 AM
Yes, you are correct about the SD-205, you have PCB scans here:

I also sent you an email.
received a second HMG today. the good new is that my first SD203 is not dead (almost work in the second console but cannot start because of bad contact for the game start button).
The defect is MC14050 or the uPD779 input ports. since the 14050 is an old CMOS I hope it is the main problem (I will buy some new and supports today)
SD208 is a 8049 (does not start game for the same problem of game start I think)
Changed the MC14050, and the console takes cartridges again smile

[Linked Image]

It seems to be a 4 or 5 bit parallel commands sent to uPD779 (+clock and ack from 779). I will need to check values from 8049 code to see if I correctly mapped each bit
[Linked Image]
Advanced a bit more.
The commands are 7 bits wide + a clock from cartridge and an ack from uPD779

here is a schematic of SD208 8049 based cartridge:

basic config from 8049 is
P1 : bit 0-6 : command bit 7 : clock
P2: 4 line of IO + ack from uPD779
bus: 4 lines IO

IO lines are direction + fire + game select + game start + unknown.

[Linked Image]
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 03/06/18 01:02 AM
Nice to see some progress, also nice to hear you didn't fry your cart and/or console after all smile

Since the SD-208 is a 8049 too you can also dump that one right?
yes the dump should work, I just need to unsolder the 8049 and find my AVR dump code (my eprom programmer cannot read a 8049)
Posted By: balrog Re: Epoch Cassette Vision and uPD77X chips - 04/16/20 06:40 PM
One of the designers of the uPD777 has posted some design documents, including the schematic and IC layout, at https://www.oguchi-rd.com/LSI%20products.php. This might be of some use.
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 04/17/20 03:00 AM
This has been around for some time we already looked into it and sean even managed to decode de graphics rom. The program rom (and cpu) is still a big mystery though and those diagrams don't seem to help much on those. They are way over my head, but both sean and kevtris checked them out and don't think there's enough info there to figure the bit ordering.
Also unfortunately they don't show any way to dump them electronically so all games will need to be decapped. If someone can make any further progress that would be great though.
I tried contacting mr ogushi to see if he could provide us any further info, but never heard anything from him.
Posted By: starlord Re: Epoch Cassette Vision and uPD77X chips - 04/19/20 11:17 PM
Any idea if the Soundic 290/hanimex hmg7900 would be easier to dump? If anything, could the game carts (aside from the first which I think is gobeurs) be dumped?
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 04/20/20 01:26 AM
Should be the same thing, it seems it's the exact same chip with writeable memory. This is unconfirmed though, I want to send a machine for sean to decap, but I'm waiting for someone to send me another one from France since I want to keep a working one in case someone wants to try to reverse engineer it. Haven't heard from him for a while, but due to the corona pandemic people have other things on their mind so it might take a while longer to get it.

Sd-201 has nothing to dump, game is built into the console chip. Sd-204 is already dumped and sd-208 is dumpable as well not sure if Gilles ever got around to do so. The rest seem to use some motorolla mcus which sean thinks he might be able to dump electronically, I also intend to send some games with the console so this can be verified.
Posted By: starlord Re: Epoch Cassette Vision and uPD77X chips - 04/20/20 04:16 AM
That’s great to know. Thanks for your interest.
Posted By: Guru Re: Epoch Cassette Vision and uPD77X chips - 04/20/20 07:13 AM
I have the following Epoch Cassette Vision carts...
Baseball, Monster Mansion, Battle Vader, Yosaku, Monster Block & Galaxian.
If they are needed for dumping I could post them out to the person who can dump them. Or if/when a dumping method is finalised, I can dump them using whatever method is required. AVR is mentioned so I assume it is some kind of Arduino-like device that can be built from a relatively simple circuit diagram. Anyway, the carts are here so contact me if/when they are needed.


Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 04/20/20 07:50 AM
Monster Mansion is already dumped/decapped the rest are still needed, but they can't be electronically dumped so the process will be destructive. If Sean is willing to decap them (and you're ok with the destructive nature of the process) you could probably send them to him.
hello, I'm not here very often...
I still own 2x HMG 7900. I add to pack all electronic stuff for some time but it's now reinstalled in the basement.
Last time I tried I could not read SD208 but I think my clock was not stable enough, I can try again
https://www.oguchi-rd.com/schematics/logic/777/777%20Schematics.pdf is very interesting document. Not sure it fits exactly HMG7900 uPD779 but it seems close
Posted By: balrog Re: Epoch Cassette Vision and uPD77X chips - 05/19/20 01:34 AM
Looks like a document outlining the Cassette Vision assembly code for Big Sports 12 was posted: https://oura.oguchi-rd.com/777/777%20Flowchart.pdf
Relation to first Casio music keyboards?

Interesting is that the 1st generation Casiotone keyboards (Consonant-Vowel synthesis) had NEC D77x chips. I don't know if these are anything related. Here is some unfinished info I wrote down for my website.

The "NEC D77xG" (64 pin zigzag DIL) was Casio's first polyphonic keyboard CPU that was used until 1981(?). It contains a keyboard matrix decoder with 4 quick access memory settings for favourite preset sounds, those are normally selected through keyboard keys + select button, but this selection method can be also simulated by preset sound buttons connected through logic ICs (like in Casiotone 401; pulling pin 34 hi seems to mute the demo note). The sound generator is 8 note polyphonic with digital envelope and stair shaped waveforms those sound much like multipulse squarewave. The 14bit digital audio output is fed into an external resistor ladder DAC. Each sound is made from 2 layered subvoices with independent envelope, what Casio called "Consonant-Vowel-Synthesis". It can additionally select timbres through an external analogue filter circuit controlled through 8 digital switch outputs. 2 of these CPUs with different software number can be wired parallel (one polls the keyboard matrix while both read it) to produce more complex layered preset sounds (4 subvoices using 2 filters). The tone scale can be switched from normal chromatic to a slightly spread variant which produces a chorus effect when 2 layered ICs set it differently. Clock can be input at pin 37 and output from pin 35 (half speed) daisychained to another CPU, or pin 35 is used as input. Bizarre is that this special CPU contains an LCD display port that is not used in any Casio keyboard (nor would it make sense in LCD pocket calculators due to size and power consumption). The CPUs in my 201 run a little hot - possibly because the digital supply voltage has 5.2V instead of the expected 5V and the analogue supply voltage is even 6V. In Casiotone 202 both have only 5V.

The naming convention of this earliest Casio keyboard CPU family is horrible; instead of software numbers the main number increases without any logical structure. It may be that advancing the 2nd or 1st digit reflects envelope algorithm changes or size of internal memory, but it also may be simply derived from the release date. According to Robin Whittle, all these ICs seem to differ only in their preset sound set and subtle changes like whether they can do sound selection without playing a demo note. He later called the hardware family 'Series I', but I prefer 'D77xG' despite it contradicts the naming in later keyboards.

CPU number 	hardware class 	notes & features

D771G 	Casiotone 201 	layered with D772G
D772G 	'' (cpu 2) 	 
D773G 	Casiotone 301, 401, M-10 	 
D775G 	MT-30, MT-40 	 
D776G 	Casiotone 403 (old) 	later version has D990G
D788G 	Casiotone 202 	layered with D789G
D789G 	'' (cpu 2) 	 
D990G 	MT-60, Casiotone 403 (new) 	bugfixed D776G?

Like with most special Casio ICs there are no datasheets online, but with modern NEC ICs the prefix D77 is used e.g. for 16 bit fixed point DSPs, D78 for generic microcontrollers (like D7811G) and D990 can be digital codecs, so it even may be that these CPUs are (e.g. by Allen's patent lawsuit) internally completely different and only share their pinout. But the very similar sound and behaviour of affected keyboards make this unlikely. Modern NEC IC types have a huge variety of variants and their numbers are longer, so it may be that in 1980 the naming convention did not exist yet and diversified during the following few years which resulted in changing prefix numbers within one family.

Strange is that while on internet photos I saw a Casiotone 403 with CPU D990G, its service manual refers to D776G and shows a somewhat complicated flipflop and gate logic network named "set control circuit" (involving ICs TC4013, TC4049, TC4073, TC4081, 74LS123 and 2 transistors), that during active "set" switch enables the keyboard matrix place "memory set" (SI2->KC3), and once a key is held, after a 2..10ms delay it plays the "A2" demo note (connecting KI4->KC4) and then disconnects SI2->KC3 (return to play mode) to prevent data mess when more than one key is depressed during memory set. In that circuit the "set" switch output is additionally connected through an inverter to CPU pin 34 I-2. The page comes with the note "This circuit prevents to preset another tone when hitting more than two keys while the MODE switch is at "SET"... This circuit is employed only in the initial lot of Casioton 403. Later produced 403 enclose the circuit within the LSI." So apparently early D77xG versions need external bugfix circuitry to function properly, which explains the lots of logic ICs inside Casiotone 201 despite the CPU concept is quite self-contained.

I had no schematics, so this D773G pinout was based on Robin Whittle's great bulletin "Modifying the Casiotone Instruments" which is not very detailed and lacks most pin names, so some pin order within equal named blocks are a guess and (particularly 40..43) may be wrong. Despite I later got service manual photocopys of MT-40/ MT-31 and Casiotone 403/ 101, even in their schematics unused pins are omitted, so some pin names were chosen by me. Apparently all "O-#" pins are outputs, "I-#" are inputs and "IO-#" can be both.

pin 	name 	purpose

1 	  	lcd segment out (not used)
2 	  	lcd segment out (not used)
3 	  	lcd segment out (not used)
4 	  	lcd segment out (not used)
5 	  	lcd segment out (not used)
6 	  	lcd segment out (not used)
7 	  	lcd segment out (not used)
8 	  	lcd segment out (not used)
9 	  	lcd segment out (not used)
10 	  	lcd segment out (not used)
11 	  	lcd segment out (not used)
12 	  	lcd segment out (not used)
13 	  	lcd common (not used)
14 	  	lcd common (not used)
15 	SCH, I-1 	/reset
16 	SI-1 	key matrix in
17 	SI-2 	key matrix in
18 	KI-1 	key matrix in
19 	KI-2 	key matrix in
20 	KI-3 	key matrix in
21 	KI-4 	key matrix in
22 	KI-5 	key matrix in
23 	KI-6 	key matrix in
24 	KI-7 	key matrix in
25 	KC-8 	key matrix out
26 	KC-7 	key matrix out
27 	KC-6 	key matrix out
28 	KC-5 	key matrix out
29 	KC-4 	key matrix out
30 	KC-3 	key matrix out
31 	KC-2 	key matrix out
32 	GND 	ground 0V
33 	KC-1 	key matrix out
34 	I-2 	sound data in? (wired to GND | CT-301, CT-403: hi during tone select)
35 	CLK2 	clock in/out (567.086 kHz in | clock/2 out)
36 	Xtal-OUT  	outputs clock frequency from pin 37 (sawtooth-like)
37 	Xtal-IN 	clock in (1134.086 kHz)
38 	M/S 	clock in select (lo=pin 37) 
39 	IO-1 	main voice /mute (lo during preset sound change, sound data out?)
40 	IO-0 ? 	filter / volume / led out (CT-201 cpu1, CT-202 cpu1&2)
41 	IO-2 ? 	filter / volume / led out (CT-201 cpu1, CT-202 cpu1&2)
42 	IO-3 ? 	filter / volume / led out (CT-201 cpu1&2, CT-202 cpu2, CT-401)
43 	IO-4 ? 	filter / volume / led out (CT-201 cpu2, CT-202 cpu2, CT-401)
44 	IO-5 	filter / volume / led out (MT-60, CT-201 cpu1&2, CT-202 cpu2, CT-401, CT-403)
45 	IO-6 	filter / volume / led out (CT-201 cpu1&2, CT-202 cpu2, CT-401, CT-403)
46 	IO-7 	filter / volume / led out (M-10, MT-40, MT-60, CT-201 cpu1&2, CT-401, CT-403)
47 	IO-8 	filter / volume / led out (MT-60, CT-201 cpu1&2, CT-202 cpu1&2, CT-401, CT-403)
48 	O-28 	dac bit out
49 	O-27 	dac bit out
50 	O-26 	dac bit out
51 	O-25 	dac bit out
52 	O-24 	dac bit out
53 	O-23 	dac bit out
54 	O-22 	dac bit out
55 	O-21 	dac bit out
56 	O-20 	dac bit out
57 	O-19 	dac bit out
58 	O-18 	dac bit out
59 	O-17 	dac bit out
60 	O-16 	dac bit out
61 	O-15 	dac bit out
62 	+VG 	supply voltage 5..6V (sound generator?)
63 	+VD 	supply voltage 5V (digital?)
64 	VDS1 	lcd supply voltage 3.1V (not used)

Robin Whittle describes pin 40..47 very ambiguously as "O-29 to O-31 and IO-4 to IO-8, used for filter, volume and LED control in different ways. Pin 46 controls filter cutoff frequency in the M-10". I measured that these pins output an individual static combinations of hi and lo (like a binary number) to identify each preset sound so long it stays selected. Pins 39..47 generally seem to need a pullup resistor to be useable. The Casiotone 202 PCB uses all these pins to control its filters; its D771G uses all but pin 43 and the D772G pin 42..47; the CPUs themselves output to all of them. Pin 39 goes low during any preset sound select ('memory set' or 'tone memory'), which is used to mute the main voice as a pop noise blocker; however the edges of the pulse have a strange jitter that may be serial data encoding the preset sound number. Pin 34 is (according to Whittle) only used in Casiotone 301 (also my similar 401; Casiotone 403 service manual says "Input from SET switch"); it may be a serial input to select preset sounds from its OBS buttons. I don't know if it can even receive synthesis data like the later D931C; particularly the fact that in US patent 4348932 the preset sound definition itself (and not only a pointer to a ROM address) is held in a register during execution suggests that there may be hidden functions for this. The mysterious LCD port seems to output the selected preset sound numbers. There are plenty of 3V squarewaves on these pins, of those some (the active segments?) halve their frequency. With set 'memory set' switch some segments seem to blink. Pin 13 and 14 have a stepped waveform from 0V to 1.5V to 3V vice versa, that apparently is the return pole for an LC display. If you want to install a homemade LED display here, I strongly recommend to use driver ICs, because these irreplaceable CPUs run already a little hot and may get damaged by additional current. (I haven't tried to connect a display.)

I found no official specification of the D77xG. The only text that comes close to it is (here slightly edited) what Robin Whittle wrote in that bulletin about the inner working.


Successor of the D77xG family was the famous D931C sound IC, which very similar waveforms are software definable through a host CPU.
Posted By: hap Re: Epoch Cassette Vision and uPD77X chips - 01/19/21 08:00 PM
Same CPU family, possibly.
Other than that, no relation. One is a music keyboard, other is a game console. Let's keep it on-topic.
The number of pins is completely different; I think these are related only in that they have adjacent numbering/released around the same time, and aren't really related at all... Maybe.

Originally Posted by hap
One is a music keyboard, other is a game console. Let's keep it on-topic.

The topic was "uPD77X chips", and these are definitely part of them, although it may be that only the release date of NEC chips determined their number, since the Casiotone patent suggest a gate logic implementation rather than a Von Neumann architecture with address and data bus. The pin count rarely tells much, since in many MCUs with same silicon die the unused pads in smaller package versions simply remain unbonded to reduce cost. (Pin order can be a stronger hint to the employed die.) At least I see none of the NEC uPD77X type numbers used twice for as well a game and a keyboard CPU. I had examined these Music LSI chips quite detailedly. This is what I found out.

Unusual is that in Casiotone 201 the keyboard matrix is polled by both CPUs those are mostly wired parallel. Both CPUs do exactly the same but have (in the manner of SIMD vector computing) different sound rom data. So each CPU outputs its polyphonic digital audio (that per channel is already made from 2 subvoices with each a digital volume envelope) through its own 14 bit DAC and a switchable fixed analogue filter to modify the timbre. Finally the analogue output of both filters is mixed together to form the sound signal. The filter settings are static and do not change during envelopes (likely to avoid dependencies between polyphony channels). Apparently one CPU can use the normal and the other a spread chromatic tone scale to produce a chorus effect (phasing) when layered.

Most waveforms are composed of symmetrical straight and ramp sections and look quite geometric. Only the sine wave looks as round as the coarse step resolution permits. Like with the later D931C, (which was detailedly researched by Robin Whittle) the sound generator apparently can not only mirror the waveform in hardware, but also skip either the positive or negative halves or even pass only every n-th wave cycle (i.e. a wave is followed by multiple wave lengths of silence) which creates the typical buzzy bass range known from squarewave based instruments. Unfortunately the employed waveforms in this mother of all Casiotones use mainly simple symmetric ramp patterns those don't sound too great. (Successors sound better.) I don't understand why Casio didn't use more asymmetric waveforms like a real sawtooth to imitate a trumpet.

The sound generation for the 8 polyphony channels is time multiplexed, thus like in most later 1980th Casio keyboards, all register contents of sound and envelope hardware is genuinely stored in 8 stage circular multi-bit shift registers. As a form of lightning fast hardware multitasking, after processing each channel they cycle to the next entry every clock step, so a task runs every 8th step and outputs its audio increment to an accumulator that finally sums them as a 14 bit DAC output value. Also this is a Casio speciality - who knows if a foreign patent prevented them from using address counters for cycling through sound channels, but shift registers may be also just a proven concept from calculator design they were most familiar with.

The concept of this instrument is described in the US patent 4283983 (particularly focussing on the user interface with tone memory). It is based on logic gates and not software controlled. The circuit for sound selection through keyboard keys (with waveforms and envelope hardware) is detailedly explained in US patent 4348932, and the part for sounding a demo note (and improvements like layered sounds) in 4387619.

In the nicely detailed reference implementation of patent 4348932 the keyboard input from the key matrix decoder is demultiplexed and then one line per key is running into a code converter (simple sort of ROM without address decoder) which outputs for each key number a 6 bit note frequency and 12 bit sound definition data for the preset sound selectable through that key. During sound selection the sound definition data is written into a register that controls waveform and envelope generator. And the described envelope generator is truly bizarre, because by the lack of multipliers it can not(!) change volume and waveform independently. Each waveform consists of straight and ramp sections (like sawtooth) of fixed steepness, so the amplitude can increase only by making that ramp either grow row by row ("fixed mode", like building a brick pyramid bottom-up) or dive up peak-first vertically out of the zero line ("floating mode"). A waveform is always 32 steps long and up to 15 steps high. Said 4 bit volume envelope consists of 5 linear sections {increase, transform, decrease 1..3} with different clock rates to roughly approximate logarithmic shape. All envelope clocks are derived from the pitch clock. During "increase" (attack) the waveform always grows in fixed mode (like opening a voltage limiter), during "transform" at full height it morphs into another waveform (square, ramp) with intermediate shapes looking like one waveform cut out of the other (like y=min(wave1(t), wave2(t)) ). The "decrease" steps can either make the waveform shrink vertically like closing a voltage limiter (fixed mode), or make it sink into the zero line (floating mode, peaks stick out last); a square wave pulse can even shrink also horizontally (floating mode, of course making the blank section longer to keep the same frequency). The whole morphing waveform generator works by adding/ subtracting steps at a certain clock rate to the amplitude; what is done in which section is switched by gates at certain waveform step numbers (of 0..31) and a comparator that compares the actual amplitude with the waveform step number and so switches addition or subtraction of clock pulses to the amplitude counter. Both halves (the part before and after step 16) of a waveform can morph independently, but a ramp in the first half is always ascending, in the 2nd half descending, so they can form a triangular wave. A square in the 1st half stays zero and has the pulse at the start of the 2nd. The described preset sound definition uses 2 bits for 4 settings of the fixed analogue filter, 3 bits to select 5 different envelopes, 5 bits to select 18 different waveforms and 2 bits to select 3 octave shifter settings. The output DAC has only 7 bit.

But this reference implementation substantially differs from the finished instrument. E.g. it lacks vibrato, sustain pedal and tone memory, and supports only 48 keys. The "Tone" switch is digital (i.e. 2 preset sounds for each key stored in the code converter for up to 96 sounds in total). "Tone" and sound select switch are outside the keyboard matrix. And instead of one demo note it even sounds a sequence of 3 (C4, C4#, D4) - a gimmick that was not implemented until the (technically very different) CT-8000 of the Symphonytron stage organ. The reference implementation even seems to use only positive half waves and may lack the mirroring mode for symmetric waveforms. The actual Casiotone 201 IC supports 8 instead of only 2 filter control outputs and its envelope generator definitely can change amplitude (likely logarithmic using a ROM lookup table) without morphing the waveform. It doesn't seem to distort all attacks by simulated voltage limiter envelope, but rather add a 2nd waveform (symmetric, i.e. quaterwave definition read out of ROM?) with short decay envelope to imitate things like string pluck noise of acoustic instruments. Several of these short waveform blips are eastereggs on the black keys, as well as even an unused sine wave, which may be even there for internal computation, because US patent 4453440 mentions a fast multiplication method based on subtracting 2 phase shifted versions of the same sine wave read from a ROM lookup table. Possibly also the bit shift multiplication network from US patent 4590838 (D931C predecessor) is used. While I don't see the pure morphing envelopes from patent 4348932, various preset sounds employ trapeze waveforms those may be indeed based on a triangular wave truncated by a vertically mirrored static version of said "fixed mode". In other sounds it even morphs a triangular wave by the "floating mode" sinking motion. So it may be that Casio indeed layered a modified version of their morphing waveform generator as the "vowel" with a technically different, ROM based attack waveform as the "consonant", hence the name "Consonant Vowel Synthesis".

The concept of geometric waveforms those gradually change shape by growing out of the floor or being truncated from one side to modify timbre has very strong similarities with the "paper sound" technique that exposed paper cut shapes as waveforms on film to be played as the sound track in a film projector. Also here timbres were modified by gradually cutting shapes by means of stopmotion cartoon animation (e.g. by moving a black shade over parts of the bright waveform). On the same idea the Russian Evgeny Sholpo created in 1930 the optical synthesizer Variophone - a mechanical contraption with waveforms on exchangeable spinning cardboard tonewheels that was used to compose polyphonic music for cartoon movies that sounded surprisingly similar like chiptunes.

Nevertheless that a Casiotone 201 doesn't sound overly great, it would be fascinating to simulate the original morphing waveform envelope generator of the patent 4348932 prototype in software (or perhaps even FPGA) to explore what it sounded like. This was the mother of all Casio keyboards, and this bizarre piece of minimalistic gate logics design without multiplication is so Pong-age - a weird chip invention like Atari Video Music that deserves to be preserved.

US patent 4387619 poorly describes a later variant of said reference implementation; the sound and envelope generator here supports 84 keys, an 8 bit DAC, vibrato and sustain. Its implementation is much more complicated (twice schematics size) with plenty of multiplexing, involving e.g. instead of the code converter a ROM followed by a bunch of gate logics to translate its 8 bit output into 13 control bits. Main reason for this was likely to implement a so-called "staggered multi-performance mode", i.e. a preset sound can consist of multiple layered subvoices occupying 2 or 4 polyphony channels ("duet", "quartet" - a feature that was not released until the much later "unison" modes in the CPU controlled Casio CT-6000), which needs independent management of key presses and polyphony channels. In an LSI chip without software control the routing is quite a mess - involving plenty of additional shift registers to memorize which key press belongs to which sounding note and such stuff. The master clock is stepping the shift registers with 1MHz, which permits rapid 8µs polyphony multitasking. The preset sound definition in ROM here uses 2 bit attack, 2 bit release, 2 bit period ( = pitch?), 1 bit delay, 3 bit waveshape designation (1 bit = fixed/floating, 2 bits select sawtooth, rectangle, triangle), 1 bit vibrato, 1 bit octave. But this system looks even more restricted than the first implementation - allowing only linear attack-decay envelopes without held notes (this resembles MT-30), and apparently the "floating" triangular wave is gone. Worst is it lacks the transform effect. At least waveforms have here 64 steps (center at 30) with 30 step height, and the delay bit can make the triangular wave asymmetric by slowing down attack. Unfortunately this patent text doesn't explain much, but rather describes wiring in lengthy sentences and omits details (like ROM data format), which makes it hard to understand. The key feature of this circuit is apparently the "staggered multi performance" mode, which loads 1 or 3 additional preset sound definitions from ROM as subvoices; 2 bits "minute difference" (+1/64, -1/64) apparently allow to detune these for chorus effect, 2 other bits set their octave range. This sound generator supports 7 octaves, but the highest one cheats by only repeating the 6th octave (foldback) with waveform changed to "floating sawtooth". The delay bit here apparently can delay a subvoice, and when with "quartet" multiple subvoices set this bit, the delays accumulate to make them sound one after another. According to the text, apparently the circuit is multi-timbrale enough that selecting a new preset sound would not affect held notes (201 can't do this), and other parts (mentioning "12 scales", perhaps poor translation) sound like that it can even transpose. The demo note (named "sample tone") here is indeed a single note. The digital vibrato is implemented by making a frequency derived from the clock add and subtract 1/64 (i.e. 1 waveform step?) to the waveform.

But also this implementation does not describe a finished instrument. E.g. it supports 84 keys, does not have preset sound selection through note keys (only mentioned as optional variant), no filters and has switches for vibrato, sustain (aka hold pedal?) and demo note on/off placed outside the keyboard matrix. Interesting is that the "minute difference" effect in layered preset sounds uses for chorus the same addition of +/-1/64 like the vibrato circuit. In the actual 201 the phasing disappears (at least on one channel on my scope) when vibrato or spread scale is on, so they obviously share the same internal resources. However the 201 does not reduce polyphony in any preset sounds, which proves that it is not based on the "staggered multi performance mode". Interesting is also that Casio refers internal polyphony channels as "lines" - a term that was later used for PD synthesis.

At this time Casio patented a lot of things those didn't make it into the final instrument. E.g. US patent 4476766 (priority date 1980) describes a key split mode with simple "any key play" sequencer to manually step with 2 key groups through each a previously recorded main and "accompaniment" (rather obligato) voice. The note data is stored here as key matrix signals (12 keys in each of 4 octave groups) in 2 RAMs. Although with timers it could recognize simultaneous notes (e.g. chords) to be stored as one step, it did not store note or pause duration and thus could not do autoplay, nor there was edit. The illustration drawings blatantly resemble 201. US patents 4522100 and 4594931 were a simpler variant without 2 simultaneous timbres; US patent 4361067 even describes a variant with playback volume change using different keys (instead of velocity) during "any key play". These 3 could also set the keysplit point through a simultaneous switch + key press (not bad for simple gate logics). Although these patents already mention loading note data from external means like barcode or RAM-packs, the first remotely similar feature in a finished product was the "one key play" in the monophonic Casio VL-1 (which had edit and autoplay), and even the barcode sequencer of VL-5 was still monophonic.
Posted By: MaaaX Re: Epoch Cassette Vision and uPD77X chips - 02/11/21 07:44 AM
Hello everybody.

I'm planning to develop an emulator of the EPOCH Cassette Vision for the RECALBOX project.
Actually I'm exchanging with Mister OGUCHI Tetsuji about the architecture and the instructions set of the NEC uPD777.
When I will understand perfectly how it work, I will share my informations.

MaaaX ^^
Posted By: ssj Re: Epoch Cassette Vision and uPD77X chips - 02/11/21 08:43 AM
We're also working on it, I think it would be of best interest if we merged our efforts. I will pm you.
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