CYBERYOGI =CO=Windler

Yes, MT-205 is MT-520 based. The CPU is close relative of PT-100 and MT-88 but with different software, and because MT-520 has a sample based percussion IC "OKI M6294-02", it doesn't need the CPU blip percussion channel and so uses the surplus polyphony to layer 2 audio outputs for a thicker main voice in the manner of classic Consonant-Vowel synthesis and even can do a stereo chorus within the CPU. Percussion often differs among Casio models with same CPU due to changed analogue filters and in analogue percussion instruments even omitted individual drums (output pin disconnected or wired to another drum). E.g. the famous rusty base drum of PT-100 sounds much tamer in other keyboards with this CPU. E.g. MT-40 had a terribly dull analogue snare that got fixed in later models. Casio PT-100 is a cheapened single-chip version of consonant-vowel hardware with accompaniment (sort of dumbed down MT-65). The LSI "Hitachi HD61702xxx" (100 pin SMD, pins count anticlockwise, xxx = software number of internal ROM) is the CPU of Casio's last generation of non-PCM home keyboards. It was their most sophisticated squarewave and stairwave hardware with functionality resembling a D930G and D931C pair with DAC integrated into a single-chip. Unfortunately compared with D930G the functionality is very restricted. So the keyboard matrix supports only 12 preset sounds and rhythms, and beside a simple sustain switch there are no sound or accompaniment variations. The HD61702 has separate analogue outputs for polyphonic melody, chord, bass and obligato channel; the 8 note polyphony is shared among these. Also the blip percussion (can be disabled through 2 matrix diodes) is part of bass and obligato. Like the early HD44140, the upper and lower DAC bits for each channel have separate outputs those need to be combined through an external voltage divider (small resistor network) to reduce noise; the mixing ratio is 1:69 (1:110 at both ends of bit compensation trimmer) for main voice and 1:100 for others. All DAC outputs need 390 Ohm pulldown resistors against DAC ground 0V. External trimmers can be used for bit compensation to adjust smooth transition. The internal DACs also have plenty of individual supply voltage and ground pins to permit signal tweaking, and even their LSB is accessible on pins 25..34. There are 3 switch outputs for fixed main voice filters; one is only used as a pop blocker to mute during switch operations ('mode', 'chord', 'memory stop', but not preset sound changes). The CPU supports a ROM-Pack port and key lighting LEDs. An optional SRAM can be connected as sequencer memory. The sound generator seems quite similar like D931C. The preset sound waveforms are 5 bit high (up to 30 steps during attack, 18 steps for continuous tones) and apparently consist of 2 stairwaves with independent volume envelope, those can be detuned against each others for chorus and phasing effects. Most waveforms are symmetrical and seem to be made from up to 4 quaterwaves those are each 8 steps long and can be flipped and mirrored. Like with all stairwave instruments there is no interpolation, so the wave shape and height does not change with note pitch and all blockiness also remains in bass range (unless smoothed by external fixed filters). Interesting is how the waveforms are composed. E.g. the 'flute' resembles a blocky sine with small square "nipples" on their peaks those vibrate irregularly for wind noise. The 'piano' uses a strange geometrical trapeze shape with varying sunken center to change the harmonic contents. It was really an art to construct good sounding waveforms at that time, and yes it can sound nice. However unlike D931C the envelopes seem to be linear and end too soon, but this also may be result of too low DAC resolution. As far my analogue scope can tell, it may have only 8 bit (5 bit waveforms + 3 bits for 8 polyphony channels), but possibly the envelope resolution is a little finer. The blip percussion even seems to use only one DAC halve; at least their decay envelope doesn't look linear, and lissajous patterns on my scope hint that rough timbres are not samples but partly contain shift register feedback noise with varying bit patterns. Possibly the synthesis uses noise modulation (US patent 4656428) that adds random numbers to the readout address of a very low resolution sample to make hiss timbres more vivid. The versions of "Hitachi HD61702xxx" ("xxx" = software number of internal ROM) differ in accompaniments, preset sounds and additional features. software number hardware class notes & features A02 MT-88/PT-100 original version A03 MT-520 Super Drums support, uses percussion IC M6294-02, melody=2 layered outputs A04 SK-200, SK-100 combined with sampling CPU M6283-02 + percussion IC A06 Hohner PK60 (SK-100 variant) modified A04?, combined with sampling CPU M6283-06 + percussion IC

Speak&Spell hardware has been fully deciphered and is emulated in MAME (so you can record the WAV output). Also various old synths and keyboards (including even a somewhat off-sounding Casio CTK-551) exist in MAME now, which AFAIK even supports midi-in (haven't tried). If you want the real thing, there is even a midi kit for Speak&Spell: https://hackaday.com/2012/02/09/midi-controlled-speak-and-spell Sharp speech synthesis AFAIK the Sharp speech engine has not been emulated yet. I collect and have repaired many Sharp talking clocks, (rebranded) watches and calculators. The CT-660 exists in a German (CT-660G), an English (CT-660) and a Japanese language version. Strange is that on eBay the German version is much more common than the English one, while I never saw the Japanese model at all (see youtube example, front is labelled "ELSI QUARTZ" instead of "TALKING TIME"), so it may have been a prototype. I love the way the alarm starts with a 5-note jingle, then announces the time and then plays a longer squarewave melody ending with a trill (a bit like a ringtone). When waiting 5 minutes, it repeats the alarm and says "please hurry" or something like that (German version "Bitte beeilen!"). The German version rolls the "R" in a funny way and so e.g. pronounces 11 as "Errlf" instead of "Elf". The Sharp CT-660 was the world first digital talking alarm clock and initially very expensive (200 US$ or such). It has a volume knob and some models have a little silicone rubber plug at the left case site. When poked out (be careful - the material rips easily apart) it reveals 2 pins wired parallel to the speech button (keyboard matrix), so it could be installed in contraptions to automatically announce time or act as a stop clock, or connect a bigger button for impaired people. (The yellow one on top is IMO too small for an alarm clock, and only switches to slumber instead of proper "alarm off", so it keeps repeating until using the slide switch in the lid at case bottom.) The Sharp CT-661/665 has simpler functions (no stopwatch etc.), different melody (very shortened "Sah ein Kab ein Röslein stehn", less nicely made) and operation is optimized for the blind (i.e. different sounds guide through clock set modes instead of all those slide switches). The 1980th "Vox Clock 2" contains the same hardware without LCD and has a lovely male robot voice, which despite graininess is well understandable. It only has a little speech glitch that pronounces 12 as something like "thrown" or "throne" instead of "twelve" (like when the wavetable algorithm fails to say "two" and "one" at the same time). The 1990th "Vox Clock 2" has an additional LCD but uses a sample based chip with English female voice and only 4 beeps instead of melody. The CT-660 hardware is quite complex, containing a clock CPU (32KHz) on the front PCB, a separate speech CPU (4.1MHz), a DAC (or sound?) chip and audio amplifier. Most of the PCB is occupied by a quite big discrete stepup converter to increase the 3V battery voltage (2x AA cells) to about 5.5V(?) for louder speech output. I later bought a broken specimen that instead of the external DAC chip has a hybrid resistor ladder DAC with thinner sounding voice. (Only the LCD worked no speech and some buttons failed because traces were corroded by battery and someone drowned it in oil - yuck!) The Sharp EL-640 talking calculator even has 2 speech CPUs (or an additional ROM?) because it speaks more words (for clock and calculator) and runs on 4 AA cells. The simpler EL-620 (no clock) is slimmer and so depends on 2 unusual thick button cells. Sharp voice synthesizer things use a grainy but nice sounding kind of wavetable speech hardware. Like Speak&Spell, when shitshot by power glitch (battery wiggling) they make plenty of freakish noises. E.g. the chip can playback speech at half speed or interprete the same data either as speech or musical notes (squarewave with linear decay envelope varying with note length). Even the EL-620 does this despite it has no melody. Talking watches with Sharp speech chips (e.g. by Trafalgar, Omni VoiceMaster, Micronta VoxWatch, MeisterAnker) use similar technology with smaller COB chips. Loose solder joints at SMD parts and broken PCB traces are typical issues Instead of lithium they unfortunately use strange thick alkaline button cells those are prone to leak forgotten inside. I wrote more about the Sharp speech hardware here: https://forums.bannister.org/ubbthreads.php?ubb=showflat&Number=120188#Post120188 https://forums.bannister.org/ubbthreads.php?ubb=showflat&Number=120195#Post120195 Despite many talking clock brands, only few speech engines exist. In 1980th beside Sharp only Seiko made their own speech synth chips. Seiko (WristTalk A964, A965, A966) watches use grainy lofi male samples and have a big COB containing 3 silicon dies, which has user selectable English and one other language. The Seiko world time clocks (World Time Voice Alarm DA716K) speaks English and seems to use grainy female wavetable voice. The pyramid alarm clocks (PyramidTalk) use a very different chip for each language and have female voice. English and Japan version have calendar with date and day display (LCD layouts differ). The German issue has none and the user interface differs (hold up/down buttons to set time). 1990th Seiko watches have a higher resolution female sample voice. Most other 1990th talking watches and alarm clocks use Holtek COB chips, those are sample based and can be recognized by the rooster (cockadoodledoo) alarm (often also cuckoo and some others) and typically female sample voice. Casio speech synth hardware Also Casio made very few talking alarm clocks and calculators using own SMD speech chips (grainy wavetable like Sharp, but female voice). I own the Casio SQ-200 (cube shaped LCD clock) and of course a TA-1000. I experimented a lot with the Casio TA-1000 speech CPU "Hitachi HD61912 C02, 3M13" (60 pin SMD) which communicates with a main CPU that is likely a "NEC D1864G" variant (64 pin SMD) like in Casio ML-81, ML-90 and such. I desoldered various pins and examined the behaviour. I also found test pins in Casio calculators and VL-Tone, those display strange counting numbers on LCD and output data (rom contents?) on keyboard matrix pins. What I mean with that Alexa is no fair comparison with offline speech synths is because these speech assistant cloud apps render everything online in datacenters fed with huge quantities of bigdata. So it would not surprise me if their neural network continuously compares spoken and written versions of the same texts (e.g. official TV news) from the internet to optimize pronunciation.

AFAIK the first Yamaha PortaSound keyboards used foil contacts (much like in nowadays cheap PC keyboards) instead of conductive rubber, which may have been considered too unreliable at that time. How long rubber key contacts last depends not only on the material (quality silicone vs. butadien rubber or shortlived plasticized PVC trash) but on how the key mechanism acts on the end of key travel to prevent crushing the contact (or punching a hole through) when repeatedly pushing keys too hard. I.e. the key end has to knock on a hard surface (hopfully buffered by felt to muffle the knock) before the rubber dome gets completely crushed. That's likely why good aftertouch keyboards are more expensive than only velocity sensitive ones. While velocity only measures the timing between pressing 2 such contacts under each key, aftertouch (at least polyphonic) needs to sense the actual pressure (i.a. electrical resistance) on each contact, which makes them more vulnerable to chemical decomposition or mechanical variation and wear of each key. (Hence e.g. the monophonic aftertouch in Casio CT-6000 simply senses rotation of the entire key mech metal frame by a potentiometer to avoid this.)

For robot voices controlled by keys there is the payware softsynth Chipspeech, which contains plenty of remodelled versions of historical speech synthesis chips (listen to the youtube examples). https://en.wikipedia.org/wiki/Chipspeech Alexa is no fair comparison to any PC based text2speech, because its cloud AI likely dynamically accesses many GB (or TB?) of online text examples to pronounce things right. I find classic speech synths made from a few KB of memory much more exciting. Did you know that already in 1980th Casio released a few speech synthesizer products? These included the talking clock calculator TA-1000 (female robot voice) and several talking alarm clocks, although AFAIK none of them got famous or were particularly successful. I experimented with the TA-1000 speech chip; by behaviour it is likely a crude kind of wavetable synthesis (data reduction by concatenating waveform samples) similar like that in early Sharp talking clocks and calculators but with different voice. AFAIK a predecessor of Vocaloid did use synthesized speech before memory got cheap enough to use actual singer's phoneme samples.

The Casiotone 7000 has many stereo panning modes and can save sequencer data on datasette. The main voice corresponds to MT-65 (soundchip D931C) but is here controlled through an external CPU to handle 61 keys (later 61 key models used the normal accompaniment CPU D930G with changed firmware).

The MT-21 uses for rhythm the MCS-48 microcontroller "Toshiba TMP8048P 1104". It is almost identical with "NEC D8048C-316" of MT-40. Even the bass accompaniment is fully functional (verified by inserting into Casio MT-40 and vice versa) despite no instrument is known to make use of it. Only rom dump behaviour differs (in Toshiba a section is scrambled/repeats). The MT-205 is not related to PT-100 at all but a cheapened variant of MT-540. Of Casio PT-100 there was a bigger version with genuine analogue percusion (IMO sounds boring) named MT-88. I figured out how to additionally enable the (much more interesting) PT-100 blip percussion in it. The CPU is "Hitachi HD61702 A02". blip percussion, chord split point, octave In MT-56 service manual there is a fixed diode shown at 93 KO11->47 KI8 to with the hint "model selection MT-56" and "(MT-56 selection)" The model selection 2 diode can be at 94 KO12->47 KI8. During power-on, the CPU scans presence of these 2 fixed matrix diodes to set the general operating mode of the instrument. The PT-100 contains none, the MT-88 both. Wire them through 2 switches to get interesting behaviour changes. Theoretically even push buttons are sufficient instead of locking switches, but you would need to hold them during every power-on to select the mode. model select 2 model select 1 percussion type chord spit point octave blip A#2 hi X blip A#2 lo X blip C2 lo X X analogue F#2 lo While upgrading blip percussion instruments with analogue percussion is not worth the effort (plenty of additional discrete circuitry), the opposite is very easy and even automatically disables analogue percussion (CPU pin 98 FC4) when a blip percussion mode is selected. Great is that the chord section key split point printed on the case allows to identify which type of percussion is inside; only melody section starting on F#2 means analogue. The analogue percussion mode disables blip percussion and instead outputs an additional continuous bass voice in accompaniment and percussion trigger pulses on key matrix outputs KO1..KO7, those can be demultiplexed by AND comparison with CPU pin 98 FC4 to trigger external analogue percussion circuits (see MT-88). All blip percussion modes turn the "synchro start" button into a "synchro/ key select" button that first waits for pressing a white key to select a rhythm (and exits with wrong key press). Interesting how other modes introduce various bizarre glitches and throw a wrench into key lighting modes (of MT-88). Without these diodes, the keyboard is assigned 1 octave higher, so in melody guide mode you have to play 1 octave lower(!) than what the leds indicate, and because soon you end up in the chord section, you can not reach some requested notes at all but only step further through the song by pressing "one key play". Also the highest keyboard octave in 'flute', 'strings' and 'celesta' makes mess; above C4 they play disharmonic low notes those form no regular tone scale and grunt lower than the normal C1. Maybe a lookup table ended too soon to save ROM space, but possibly this was a test mode or even a hidden message in the chip. The keys from C#4 to C5 play the notes {B#-1, B#-1, B#-1, B#-1, C#-1, C#-1, C#-1, B#0, B#0, G1, E#1, B-1}. At least the G1 and E#1 are detuned against the normal notes. The falling sequence length of equal notes hints to a part of a waveform or envelope curve, or did aliens compose this sequence to contact us?!? (Recording this in the MT-88 sequencer and replaying it on a normal preset sound plays the regular notes C#4 to C5, which proves that the glitch is in the sound engine itself and not keyboard decoding. Switching back to normal diodes keeps the high and faulty notes in the sequencer, which shows that the SRAM stores note numbers and not key numbers.) With "model select 2" diode the chord section is too short to play chords like displayed in chord guide mode. Instead you have to play those chord notes an octave lower, which is pretty confusing. Only with "model select 1" or both diodes the guide modes work ok.

I vote for multipulse squarewave (Casio VL-1 synth). Of course also Consonant-Vowel and its successor SD was nice. The first PCM engine (classic SA-series) and its high resolution version "CD" (MT-540 etc.) included some freakish algorithmic synth sounds those don't exist in any later models.

If you think this keyboard looked bad, you haven't seen my CZ-101. A decade ago I bought it from eBay, looking like it survived a house fire. The case is scorched and severely warped (keys bulging up) and because it lacked some screws(?), the owner wrapped it completely in browntape, which glue has stripped all print and paint from the front panel. It also had PCB traces corroded away (may be a granny plugged it into mains "to warm it up" for drying a flood of extinguishing water inside) those I patched with coil wire. So the aluminium coating on the cardboard shield was mostly eaten away where it touched conductive parts. I also had replaced a missing key from a Medeli(?) keyboard (fixed with hotglue and a piece of blister plastic to attach it). The PCB works ok (even including LCD) although the instrument looks like vomitted out of hell and of course keys respond very unevenly.

The main mainboard of my Colani bigtower runs Win98SE on a DFI K6BV3+/66 mainboard with AMD-K6-3+@550MHz, 768MB RAM, Voodoo1+GeForce3 Ti220 graphics card and real ISA slots with 2 soundcards SoundBlaster AWE64+Gravis Ultrasound Classic.

The MT-20 sound engine is much simplified compared to actual Consonant-Vowel, so it lacks many filters and only layers 2 multipulses instead of stairwaves and (that's bad) volume envelopes use linear envelopes those decay too fast. So sounds are between consonant-vowel and VL-1 (rather the latter). The chip also has no interesting eastereggs. The LSI "Hitachi HD44140" (54 pin SMD, pins count anticlockwise from below the left stub pin) was Casio's most simple polyphonic single chip main voice hardware of early 1980th keyboards. Compared with the very versatile first generation predecessor D77xG, it was cut down to have as few functions as barely needed for a short beginners keyboard. So despite 8 note polyphony the keyboard matrix supports only 37 keys and 8 preset sounds with 1 sustain and 1 vibrato switch. Unlike D77xG the chip produces no feelable heat, so the transistor count was likely minimized for long battery life (possibly created for the mythical solar cell powered mouth organ that became the PT-7). A bit strange is the integrated DAC that outputs its lower bits (at increased level) only on a separate pin; also the highest bit is separately output in normal and inverted. All these have to be combined through an external voltage divider (small resistor network with ratio 1:64), which was likely done to reduce noise. The only 11 DAC bits also have separate output pins (not used in any instruments I know). The sound generator is a very simplified variant of Consonant-Vowel synthesis. Each preset sound is made from 2 layered multipulse squarewaves (8 steps long?) crossfading by simple volume envelopes those do not change with note pitch. Each step can have only the height {-1, 0, +1}, i.e. protrude fully up, fully down or be zero. (I.e. unlike D77xG there are neither ramp nor curve sections.) The linear envelope and low bit resolution make it sound rather artificial, but the unusual sonorous waveforms are unique and the high internal clock rate (1.425 MHz?) prevents cold aliasing noise. The preset sounds 'clarinet' and 'piano' set the external fixed lowpass filter to 750Hz, else it stays 1.1kHz (seen in MT-11 service manual). Unlike D77xG there is no spread scale, i.e. holding the same notes in different octave causes no phasing (but phase changes among multiple key presses, thus there are no octave dividers involved).

I got on eBay the guts of 4 dead Casio CT-420, including 4x 49 keys those look at least pretty similar like those for CZ-1000/3000/5000 on that BustedGear website. With boxes full of damaged electronic spare parts it is hard to estimate if I was sitting on a gold- or rather a land mine (lithium rechargeables tend to be the latter). But those keys (may be 2 or 3kg of them) look blatantly like they might be the same. They came attached to a punched sheetmetal rail with springs on their back, forming each a 49 keys assembly (without PCB mount, which was likely part of the plastic case, full of decomposed foam rubber residues). I dismantled them to save space.

With hardware soundchips it is not only zipper noise but also very fast internal mixing of polyphony channels (500kHz or higher) that makes them sound better where software imitations turn harsh and thin. Not true. Japan still sells VHS recorders and cassettes, many japanese use flip phones (they name it a galapagos phone) and also tube amplifiers and record players have their fandom. Decades ago in Japan sale of used electronic devices would have almost become outlawed by a new electric safety/liability law, but the Japan Synthesizer Programmers Association (JSPA) started a huge protest to undo that deskdoer law. https://www.techdirt.com/articles/20060327/1244238.shtml

I own an XW-PD1 but haven't really tried to learn it. But plenty of stuff can be assigned to the pads. May it be that someone assigned the power switch to a pad (or caused the same by corrupted SRAM or flash contents)?

AFAIK the analogue sound output is NOT multiplexed at all, but one sound chip feeds its digital audio into the next one, so they get digitally summed and finally output by the last soundchip in that chain through a single resistor ladder DAC. Analogue multiplexing with demux after DAC existed in other hardware families of that time (and Bontempi even did it for stereo), but not the sinewave hardware.

This is an old eBay photo showing many details. (I hope this wasn't too big (591KB) as a forum upload.)

The Casio Symphonytron 8000 stage organ (very rare, prototype?) uses the RAM cartridge Casio RA-2, which looks very much like a white version of the RA-5 for CZ-series synths (CZ-101 etc.) and may be even compatible. (I own parts of a Symphonytron system but haven't investigated this further.)

You can not install any other CZ-series LCD into CZ-230S. While others have matrix displays (possibly a generic industrial part), the CZ-230S needs a custom layout segment display (much like a watch or calculator LCD) that can not be swapped. It might be possible to emulate the CZ-230S display on e.g. an arduino with 2 row matrix display by writing a program that simulates the segments, but that would be a complicated task and nothing generic.

The hardware is a relative of MT-540, which service manual AFAIK is on Elektrotanya. And yes, keep that dryer sheet out - if it is something heavily perfumed, the odours may decompose rubber contacts over time or even crawl into chips and damage their package (like known from mothball chemicals based on benzol).

IMO everything to 100€ is definitely fair, higher if a fan insists on it.

AFAIK generic midi controller code for arduino exists. You would need to program the MT-65 keyboard matrix into it for accessing control panel keys. Keep all locking preset sound/rhythm keys unswitched (press one of them half down) to make midi selection work.

The MT-70 has only 2 indentical sinewave soundchips (may be Casiotone 501 too), while Casiotone 701 has 3 (i.e. 12 instead of 8 note polyphony). Also my Casio AT-40 contains 2 of these. If only every n-th note is audible, likely one of the soundchips is dead or a pin disconnected. Their digital audio is daisychained from chip to chip instead of using separate DACs, which may complicate fault search.

It's time to edit the timeline and eradicate the noughties. After 2000 (9/11 2001) everything went wrong, so mankind got infested with a world made of wars, torture gameshows and mobile radio radiation. In my "DRM" sci-fi script all media get replaced by streaming from an uncrackable cloud technology, and owning any physical media (also paper, phono records etc.) get outlawed to make piracy impossible, resulting in a Fahrenheit 451-like world with hidden personalized censorship because nobody can read books etc. anymore without being automatically logged in by biometry. I started writing it in 2007, but the modern filterbubble situation with disappearing physical media by streaming services comes close to it, and my concept of the "hypercloud" (which backups everything into >1000 server buildings simultaneously and never forgets, while privacy is ensured/simulated by an undefeatable AI) came shockingly close to what nowadays got known as "blockchain" (beside that the real one is slow and a terrible energy hog). I wrote plenty of sci-fi/fantasy plots, although most are yet only concepts (people have no names etc., some lack an end).

You may need to port Robin Whittle's code to a RasPi or even Arduino to control the synth parameters through midi. It is a slow serial protocal likely not hard to interface with a cheap MCU.

My tooth necks crumble apart, throat/larynx is a pussy pulp and hemoroids squirt assblood into the bowl when I skip a poop an hour too long. I don't know if it makes me more depressive that covid lockdowns happen or the fact that these did not change my daily life at all (except that I learnt how to use even less loopaper by washing my useless bodypart under the tap after pee). I had completely dismantled my main PC (jigsawed new case holes etc. into the Colani bigtower, adding complex shieldings) to install a 2nd mainboard (mITX with Ryzen 2400G). The brand new BeQuiet SFX-L PSU had committed suicide and killed my brand new mainboard Asrock AB350 and RAM due to undocumented "modular cable" connectors. :-[ The crap was from eBay and the vendor returned the faulty PSU for destruction of evidence instead of the requested repair. So I wasted >200EUR and had to buy a new (now different brand) PSU, new mainboard and 16GB RAMs. I am still writing on some sci-fi movie scripts. One of them (DRM) is about an uncrackable wireless internet successor driven by AI, that is slowly turning into a dictatorship by hidden personalized censorship. With arise of things like Siri, IoT sensors everywhere and Cambridge Analytica electing Trump through filterbubble-borne personalized fakenews etc. 80% of it has turned into reality.

I have a German version of such a VHS video (of Casio CT-670?). The musical score display in it looked like made on an 8-bit homecomputer.