CYBERYOGI =CO=Windler

I don't own an MZ-2000 (that thing is huge!), but if your Keyboard contains a soldered 3V lithium button cell, search for a broken PC mainboard. In my Amiga memory expansion card was a soldered dead 3V battery (orange Renata block, for system clock) that I replaced with the CMOS battery holder of the dead PC mainboard. Danger!: Do not confuse polarity, else it may destroy keyboard ICs! Because lithium batteries do explode like blazing fireworks rockets when overheated, better do not try to desolder the old battery but nip off the contacts with pliers and solder the empty battery holder into place. If you insist on keeping the memory contents (midi sysex dump would be better), it will be complicated because you would need a temporary supply voltage source fed to the SRAM (if wired parallel, voltage not higher than the old 3V battery or it will detonate into your face) and the difficult part is not to short it during soldering. (remember: During repair, 50% of all short circuits are made with the solder tin spool... ) The MZ-2000 service manual is on ElektroTanya.

As a yogi I spend most of my life in the lotus seat. So when I play keyboard, I sit on floor in front of it, i.e. pedals are pretty useless for me, but I sometimes pushed a fill-in button by toe. I guess I will somewhen construct a belt-pull controller operated by trunk motion to simulate a volume pedal. By the way, also my PC keyboard (AT size, resembling "IBM Model M" with mechanical keys) is always resting on my lap in lotus seat. With music keyboards this position doesn't work well (too shaky) but I can type texts quite well. The monitor is a 22'' CRT in front of me, resting on the large wooden DIY desktop case of my Amiga workstation.

Are the keys missing or only cracked off? If you still have the keys, they can be re-attached with a piece of thin PE/PP sheet plastic (cut out of a blister package) and hotglue. You have to dismantle the keyboard assembly, which has many screws but otherwise isn't difficult. I have fixed several broken keyboards this way. If keys are lost, gut out a broken Casio from that era (e.g. MT-240 would have correct size), but even those from a cheap Chinese midsize tablehooter (Medeli etc.) often can be modified to fit. You may even carve or saw spare keys from wood if you want and attach them the same way with hotglue and blister plastic. With foreign keys you may need to file pieces off and attach a plastic piece with hotglue to push down the rubber contact at the correct spot, but this is all easy to master. Often several keys form one piece (connected by a plastic strip with screw holes at the top), but the piece will be anyway shorter than the whole keyboard, thus different keyboard length of the scrap keyboard doesn`t matter.

Sorry, I made a mistake. I compared the manuals and saw that the regular Casio CT-670 (aka Hohner PSK75) has no velocity; its features seem fully identical with MT-750 (beside additional sustain pedal jack). However Hohner released the PSK75R, which looks the same but (I think) has velocity sensitiv keys. Possibly this had the equivalent "Casio CT-670 Plus" (name seen on eBay, existence not confirmed) as the velocity sensitive version.

I am collecting home and toy keyboards and document the hardware. What I particularly like with 1980th Casios is the unusual waveforms. Especially early stuff is based on partly layered and filtered multipulse squarewaves and stairwaves (Consonant-Vowel synthesis) found nowhere else. When they came out, certainly some people thought they were unrealistic and worse than its competitor Yamaha, but nowadays its the special timbre that makes old Casios much more recognizeable than their Yamaha counterparts. The later "PCM" Casios used a unique softsynth-on-a-chip that had (at least before CTK-1000) very good interpolation to blend between key split zones and remove aliasing noise (many modern Chinese tablehooters still fail here). Small Yamaha AWM keyboard (I down't own others) had much more noticeable coarse steps and other irregularities. Also the program loop synthesis (algorithmic) timbres of Casio SA-series variants are quite unique. With modern Casios I find the XW-G1 synth most interesting (I don't own one). It can sound e.g. like a massive polyphonic version of Commodore C64; I know no other complex synth keyboard sounding like that. The HT-6000 contains 2 PROMs instead of ROMs. May yours have died of bitrot? The rom dump can be found on elektrotanya.com, but if yours are faulty you will need someone with an eprommer to burn these on 2 eproms and replace the bitrotten PROMs with IC sockets for them. When I got my own HT-6000, it had some cracked panel PCBs, so I had to solder wires to patch broken traces. May these have a general problem with mechanical tension during transport? (E.g. also the Casio KX-101 keyboard boombox PCB tends to shatter very easy when the instrument fell on its protruding switches. I fixed 2 with the same damage.)

People claim that Casio CTK-1000 was a singleton without variants. But a predecessor might be Casio CT-770. Its functions look like CT-670 (a velocity sensitive fullsize variant of MT-750), but as a novelty it had additional illuminated buttons for DSP effects (reverb etc.). Has anybody heard if it has similar dynamic synth timbres like CTK-1000? (By space reasons I definitely do not want to buy one to try it out.) -Which CPU has the CT-770? Is it a "NEC D939GD" like in CTK-1000 (i.e. IXA synthesis), or is it based on earlier hardware (e.g. D937GD of MT-750 or D938GD of MT-540) with external effect DSP (e.g. the "OKI M6583-04" from VA-10)?

Robin Whittle already examined the data protocol of MT-65 hardware (sound IC D931C). May be somewhen in far future I develop an addon with touchscreen (may be running on old PDA or Raspberry-Pi) that can communicate with the sound IC of classic Casio keyboards to transform them into fully programmable synths.

I finally got my hands on a Casio CTK-1000 and have examined the hardware. Despite superficial similarities it strongly differs from Casio VA-10. Here is my analysis with short review: http://www.casiomusicforums.com/index.php?/topic/6110-casio-ctk-1000-hardware-analysis-also-va-10/ By the way, If anybody is interested in raw samples or waveforms; I also have dumped the ROMs of CTK-1000, MT-750, MT-540, MT-640 and olders. (Because Casio used linked lists for infinite volume envelopes, it may be hard to re-create main voice sounds from these. There are huge data tables I haven't researched yet.)

I finally got my hands on a Casio CTK-1000. It is unfortunately excessively bulky (like a 1970th Antonelli; at least the speakers are not bad). The synthesized IXA presets respond nicely to velocity and not only turn brighter and louder, but partly into metallic and resonant distorted timbres (physical modelling?). Picked strings, organs and synth pads are very nice. It can sound like a warm analogue synth and is well suited for new age music. In any preset sound 3 synth parameters {wave, attack, release} can be edited and saved as user preset. Their values can be 1..9, where 0 is the default. The behaviour of 'wave' depends on the preset sound. What sucks is that many brass, string and ensemble timbres are only loop samples with sampled vibrato, which of course changes speed with the note pitch until the next (well audible) split zone is reached; this rather reminds to 1990th Bontempi GM home keyboards or Potex sound toys than a serious synth. Despite many DSP effects, there are no vibrato or tremolo settings; instead many voices contain an annoying delayed vibrato that can not be disabled. Obnoxious is also that there seems to be no easy way to play in the chord section chords without rhythm or accompaniment. (May be you can program this as a "style", but thats not what a keyboard should do.) There is no key split mode except as part of some "split" preset sounds. The entire thing somehow feels like an ill designed cross between MA-130 kiddy keyboard and a very serious workstation. Absolutely insane is that despite complex multi-track sequencer with even editable styles and synth user presets there are no means at all for backup, so the only way not to loose them is to have fresh D-cells inserted and keep the AC adapter connected while changing batteries. (Why is there not even SysEx dump!? An SRAM upgrade module like those for SK-series could fix this.) The manual even warns to disable auto-power-off (hold 'tone' button and switch power on) during programming to avoid data loss. Interesting is that at least through midi (haven't tried) the sound engine is multi-timbrale and there is a "local off" mode that may permit to route the keyboard input through a PC to circumvent some design flaws (e.g. key split). Despite superficial similarities to the Casio VA-10 (both from 1993), the ICs are much bigger and have nothing common. main ICs: CPU= "NEC D939GD 010, 9315BA 006" (160 pin SMD, PCB label "UPD939GD-00X, NM-110", 20 MHz? crystal clocked)key velocity IC= "Casio HG52E35P, CDHG256, 3C33, Japan" (64 pin SDIL)ROM= "NEC D23C16000BCZ 065, 9314E7003, Japan" (42 pin DIL, 2MB)SRAM= "NEC D43256AC-12L, 9310AD019, Japan" (28 pin DIL, 256KB)DRAM= "Sanyo LC33832PL-70, 3DD0, Japan" (28 pin DIL, 256KB pseudo-static, PCB label HM65256BSP)DAC= "NEC D6376CX, 92498H003, Japan" (16 pin DIL)panel CPU= "NEC D78CP14CW, 9246PX701, Japan" (64 pin SDIL, 12 MHz crystal clocked)power amp= "LA 4620, 2J1" (23 pin SIL)IC= "F MB3771, 311F40" (8 pin DIL, PCB label "MB3771P")2x IC= "Mitsubishi 5216A 2607R" (8 pin DIL)transistor array= "LB1216, 3N9" (16 pin DIL)transistor array= "LB1233, 1H8" (16 pin DIL)optoisolator= "NJL 51270,2Y" (6 pin DIL)3x hybrid= "B9HC0118, 101Kx8" (9 pin SIL)The 16 bit ROM (I dumped it) is 2MB large and contains plenty of samples and curves, as well as plenty of strange wavy ramps; possibly IXA employs the mysterious "triangular wave modulation" (https://www.google.com/patents/US5164530). With ROM removed, the panel LEDs and display ("00") look normal, but nothing responds and no sound. The CPU "NEC D939GD 010" (160 pin SMD, 20MHz) seems to be successor of the MT-540 CPU ("NEC D938GD 005", 120 pin SMD, 2.17248MHz), but unlike the latter it interfaces velocity sensitive keys and parts of the control panel through 2 external large ICs and uses most of its 160 pins to access SRAM, DRAM and 2MB ROM simultaneously (no shared bus) to increase throughput per clock cycle. Despite high complexity it fortunately does not run hot and so neither shortens its own lifespan not that of the batteries. Strange is that parts of the control panel are handled by a fairly large CPU "NEC D78CP14CW" (64 pin SDIL) on a daughterboard with ribbon cable wired to empty IC holes on the panel PCB. This hints that Casio had planned a different user interface (perhaps a professional synth?). Many D78CP14CW pins are unused; most do nothing but some output matrix signals. Possibly an LCD was planned but no software written for it. Annoying is that you e.g. can not see the effect settings and so have to tweak sound by ear and count button presses (MT-750 did the same). Also the menu structure is quite restrictive; e.g. various mode changes stop rhythm. Perhaps the panel CPU was added to save computing time in the main CPU, which has more sound glitches and irregularities than MT-540. E.g. effect buttons cause strange transient pop noises, the sample split zones are much more audible (i.e. lack interpolation) and the awesome algorithmic program loops synthesis sounds are gone. (I.e. the 'sound effect' preset consists here only of a bunch of very plain behaving loop samples.) Knowing that MT-540 was a high grade variant of the softsynth-on-a-chip (Casio SA-series), I guess that Casio threw a lot of goodies out of their algorithm to save computing time for the IXA synthesis, effect section and higher polyphony. The only special behaving preset is 'synth-lead 2', which stays always monophonic with portamento, which hints that there are many hidden synthesis parameters. The effect section DSP may be in fact hardware (seen in Casio patents) and likely uses the DRAM. So it might be possible to install a microcontroller between CPU and RAM to edit further parameters or at least backup its content on persistent memory. It also may be that the strange D78CP14CW can be replaced with a programmable microcontroller to unleash hidden synth capabilities of this thing. Somewhat similar like CTK-1000 is the much smaller Casio VA-10 "Voice Arranger", which also has a DSP effect section and can route microphone input through it. But the ICs are different: CPU= "NEC D911GF 003, 9243AA005, Japan" (120 pin SMD)DSP?= "OKI M6583-04, 2432202, Japan" (60 pin SMD)DRAM= "Toshiba TC51832APL-85, 9236HAK, Japan" (28 pin DIL, 32KB pseudo-static)op-amp= "XRAI5218, 245 214A" (8 pin DIL, PCB label "M5218APR")power amp= "Motorola AN8056, 2'D6" (28 pin DIL)3x hybrid= "B9HC0118, 101Kx8, 2N" (9 pin SIL, PCB label "CNB8X101K")hybrid= "B9XC0118, 101Kx7, 20" (8 pin SIL)Although the main voice preset sounds resemble much Casio SA series keyboards, the main ICs strongly differ from all other small Casio keyboards. The double sided PCB is fairly complex with 3 large digital ICs and plenty of discrete components. The CPU "D911GF" is such exotic, that not even Google finds its name. As expected, also the "OKI M6583" has no datasheet, but plenty of Mitsubishi ICs with "M6583..." (different pin count) are audio delay DSP for reverb and echo effects in things like karaoke machines, so technical relations would be very plausible.

People learn playing mainly on those instruments they have easy access to. I.e. no matter how great and expressive an exotic multi-thousand-EUR boutique midi controller may be, unless they coincidentally want to learn a new user interface just for fun or intellectual challenge and have the money, people won't buy it. =>No access =>no new learners =>no new players! Thus to be successful, new user interface functions must become part of those cheap home instruments those are to be expected in normal housholds and not an expensive add-on. E.g. the chance of making more people learn to play theremin is much greater once a theremin function comes for free with every motion sensing game console, than when people need to actually buy or rent a theremin (which average local music store has one installed for demo?!?) only to try it out. So it makes no sense to claim that by low demand new user interface features are only worth to be integrated in expensive pro instruments. The opposite is true; the more cheap home keyboards come with touch position or pressure sensitive keys, the more people will get habited to these features. If advanced controls interfere with novice play (a violin e.g. is very expressive but also hard to play well by its sensitivity), there can be still a button to turn it off.

I would particularly wish pressure sensitive keys (aka polyphonic aftertouch) as a state-of-the-art standard function in every cheap ordinary keyboard. To me piano size keys feel too big - I rather would wish mini (i.e. Casio SA-1) to midsize keys (even medieval church organs had them), and instead of having many octaves, there should be one long key bar controller above and/or below the entire keyboard, that can be reached from everywhere with thumb or other fingers (like the space bar of a PC keyboard) to flip octaves or do other sound manipulations. In certain analogue Yamaha stage organs there was a horizontally slideable keyboard instead of a pitchbend wheel to modulate the timbre. Such things should be also possible with any normal state-of-the-art keyboards. When turned off, everything should behave as habited from normal keyboards to prevent deterring musicians. Seeing how cheaply an average modern keys assembly is constructed (plastic + machine-made PCB + silicone contact strip), it certainly would be affordable to integrate more contacts, LED light barriers or Paper Jamz-style contacts for more capabilities. Check out how many details in game console controllers have changed from begin of 1990th till now to make them more responsive and versatile. We should have expected the same progress with average music keyboards, but since pitch and modulation wheel nothing serious has happened - why? Is it a music school dogma that requests how a keyboard has to look and feel like? The acoustic piano in its standard form is over 100 years old; isn't this pretty outdated?!? In 1980th there were innovative mass produced electronic things like the Suzuki Omnichord or Casio PT-7 foil keyboard. Come on and add such features to nowadays electronic home instruments instead of mimicking a 100 years old thump box!

AFAIK it was mainly FM stuff where Casio had patent trouble with Yamaha. But with many other things (like the single-chip softsynth inside SA-series) Casio indeed came first. And they invented a strange concept of using n-stage shift registers (n = count of polyphony channels) instead of flipflops in digital sound generators and an "adder" before the output DAC to implement polyphony by hardware multitasking (switching with main clock speed!) without space eating memory busses inside the chip. In 1st generation instruments they made some really unusual chip designs to permit fully digital synthesis with perhaps 1000 transistors. (Modern PC CPUs have up to 2.5 billions.) http://www.google.se/patents/US4348932 Check the waveform drawings in US patent 4348932 to see what I mean - It did crazy stuff to simulate envelopes without space eating multiplication hardware. And Casio stored and summed increments instead of complete waveforms to avoid 1970th Allen Organ patents. Much later in 1990th home keyboards Casio still used FM-based technologies, thus Yamaha patent trouble certainly was not an issue to abandon pro synths (they simply paid royalties).

The higher the frequency, the easier the energy can concentrate on small spots and produce heat (like a burning glass) or damages molecules by resonance effects. E.g. I own a small theremin (about 500kHz, tiny SMD output transistors) which I don't worry much about to play it. Old radio technicians report that a 1KW medium wave transmitter barely caused feelable heat at the antenna because so little is absorbed by flesh. But only few watts of microwaves can cook your retina since it concentrates so much. And effects like freak waves in irregular dense materials with "bad lens" properties (i.e. human tissue!) make microwaves even worse and biologically unpredictable. I am convinced that in 50 years people will talk about the modern age's wifi and mobile phone craze like us now about the 1950th idea of installing small nuclear reactors and plutonium batteries inside every automobile, domestic heating apparatus and appliance. Integrated point-to-point lasers with tiny amounts of visible light should replace digital radio transmitters; these will aim automatically only at the receiver lens instead of radiating energy spherically into environment and our body like nowadays mobile antennas do. I hope these can be implemented without need of software controlled beam tracking webcams in every device (NSA is watching us...). And sufficiently large displays aren't expensive anymore and surely will (not least due to smartphones) become even cheaper. E.g. Chinese MP4 media players with 3.5 inch TFT cost 5 or 10EUR on eBay. Place a plastic fresnel lens or spherical mirror in front of it would allow in music keyboards a fairly large colour screen without high cost. And the CPU is surely fast enough to handle an at least C64 to Amiga grade user interface for synth control (look what cheap Chinese Megadrive-On-A-Chip pocket game consoles can do). So nobody needs to install this atrocious wifi rubbish to make an affordable synth with nice display. I expect that cheap future instruments will be constructed similarly like the "Paper Jamz" toy instruments; a large foil covered touch sensitive surface senses controls, and everything is connected to either a small PCB or contain a single-chip CPU inside that foil, of that some areas form a large OLED touch screen. Other foil parts reach under keys and buttons to make them touch sensitive (permitting theremin-like near-field controls). Such a capacitive user interface unfortunately will also need some RF radiation, but if well designed (think of the changing hum intensity of approaching hands to a microphone plug) very little EM energy at fairly low frequency is enough to make it work. Bad is that foil PCBs may become quite unrepairable (bad for circuit bending), but they may be the cheapest method of mass producing an inexpensive digital synth with many controls.

I also used the Russian proxy "FasTun.com" (may be owned by KGB?) for web access to automatically reduce the picture file size in downloaded web pages. Unfortunately the proxy seems to be dead (or blocked by Europe?) now. It previously also often showed errors that websites had blocked it.

Wifi and mobile phone radiation uses microwaves. Although they are too weak to cook you alive, they can form freak waves in human tissue because cells act as bad lenses and so can fry neurons by local hotspots and cause DNA damage. http://physicsworld.com/cws/article/news/2009/sep/23/freak-waves-spotted-in-microwave-cavity It is all a matter of physics, but the mobile phone industry lobby does everything to ridicule this to avoid spoiling their billion dollar business of selling pocket chernobyls to the human race.

Yes, it's me who posted that. I desoldered and uploaded the Symphonytron emproms I have. But since my MB-1 is dead, it may suffer of bitrot.

My Casio hardware research is in a very early stage. I have downloaded all the early PDFs of keyboard/synth patents and try to understand them. Casio tried to imitate all kinds of acoustic instruments with strings, percussion or wind (e.g. the PT-7 was originally designed to become an electronic mouth organ). Strange is that they released tons of new instruments patents every year until 1996(?), but then it suddenly stopped and only few and in no way revolutionary patents followed from that day on. I am still employing a PC made from finest DOS hardware made in 1995 to 2002 (running Win98SE/KernelEx with 2 ISA sound cards). So no modern music software nor Windoze programming environment has any chance to run on it. May be that soon I install a 2nd small mainboard for modern Windoze inside the Colani bigtower since web browsers become incompatible with websites and the last remaining antivirus' update and boot duration takes now >20 minutes. The last time I coded something serious is about 10 years ago.

SA-series mini synth As a Casio retro keyboard I especially wish a classic SA-series remake containing the original sounds of Casio SA-21 and SA-35 with USB port, SD-card slot and all internal sound parameters editable. It should become no highend synth, but still rather toy grade for perhaps 59 to 99€. The original SA-series was based on the world first single-chip softsynth inside a tiny CPU that is unfortunately extremely hard to hack to make other sounds in systematic ways. Here are some more spects. Triangular Wave Modulation = Phase Distortion? (Casio PCM engine patents): http://www.casiomusicforums.com/index.php?/topic/5898-triangular-wave-modulation-phase-distortion-casio-pcm-engine-patents Of course also higher grade variants of that sound engine (like MT-540 or MT-750) could be simulated by this thing, but most important would be the odd program loop synthesis synth timbres from the original SA-series. May be I somewhen write a software emulator or simulator, but even with those patent texts it would be hard to figure out what is really going on inside.

It was Casio who actually invented the concept of big LCD touchscreen operated synths in 1979! Look at this patent: http://www.google.com/patents/US4440057 (US4440057) By the lack of technology they imagined the implementation as segment graphics LCDs with changable foil overlays coming with individual synth data ROM-packs or such things. It is a shame that Casio didn't continue the idea of having a simple synth feature in every cheap keyboard after the VL-Tone VL-1. Strange is that even the 2 CPUs in my Casiotone 201 (first Casio keyboard ever) contain an unused LCD segment display port (likely outputting the selected preset sound number).

Wifi is brain destroying radiation and should be banned by law! Mobile communication is the radium of the 21th century. And I *do not want* to be spyed out by my own apliances and home entertainment hardware. NSA lurking in every TV, light switch and digicam thanks to wireless connectivity is an atrocious idea! Any device containing a radio transmitter combined with software controllable microphone or camera is a spy bug. So stop this wireless insanity!

Triangular wave modulation (US patent 5164530) is an FM-like Casio speciality that generates waveforms by modulating a monotonous carrier function with a sine (or other) wave and decoding the signal by mirroring it at a triangular wave. With the same count of operators (here only 2?) the produced waveform has higher harmonics than normal FM because at high modulation the wave peaks fold back into the opposite direction. Without modulation it outputs a sine wave and so can nicely blend between very dull and bright timbres. The carrier waveform stands in ROM and so can be switched between a variety of timbres. Like with FM, operators can be combined in various ways. https://www.google.com/patents/US5164530 - Is TM part of the "phase distortion" engine or something else? I own a CZ-230S and revived a CZ-101 (had severe water and fire damage), but I am no PD expert and never heard about TM synthesis before (even websearch doesn't help much). Is this used in phase distortion synths (e.g. the later VZ-series) or is this only used in the Casio "Pulse Code Modulation" engine of preset sound keyboards? Patent 5164530 suggests that Casio at least planned to make dedicated TM synthesizers with a PD/FM-like user interface. I am reworking my technical keyboard descriptions for the WarrantyVoid site. So I websearched for 1980th keyboard patents and discovered a lot of interesting info. https://www.google.com/patents/US5319151 This is what I wrote for my SA-series page: The Casio "PCM" sound generation is apparently described quite detailedly in the US patent 5319151; it is based on a highly complex softsynth with many algorithms those can perform PCM, DPCM, FM and TM (triangular wave modulation) synthesis with sophisticated envelopes. This rather confusing 121 page tome of a patent text however is ambiguous, because it covers plenty of different implementations those e.g. can employ different counts of chip-internal sub-CPU cores for sound generation in higher grade instruments. The SA-series is surely the cheapest described "First" or "Second Embodiment" which has none. The algorithms for this version even describe how shorter tasks are stuffed with blank "dummy commands" to keep the timing in sync when different sounds would need different computing time. It works indeed very VCS2600-like - a marvel of freakish realtime programming made from one big loop (plus in "First Embodiment" one timer IRQ to compute waveforms and fill the DAC output FIFO; the "Second" does even this during dummy commands). The interpolation method with that Casio smoothly blends between wavetable sections is described in the US patent 4442745 "Long duration aperiodic musical waveform generator" It plays sections of compacted samples back and forward to implement things like long decaying cymbals. US patent 4958552 explains algorithms how envelope data is extracted from natural instrument recordings and applied on loop samples as a approximated segmented functions. The original envelope may be removed from the stored loop sample by a waveform normalizer (US patent 4691608). Most important is that these chained envelopes can have basically any length and have (unlike e.g. ADSR) no fixed count of steps. Combined with crossfading between adjacent loop samples this permits very flexible sound definition. The US patent 5319151 "Data processing apparatus outputting waveform data in a certain interval" mentions for the "First Embodiment" that the chip size is only 5x5mm, a program word has 28 bits (including lower potion of next address) and these further hardware specs: "With regard to the circuit scale and the operation time of the specific embodiment (PCM sound source system capable of producing eight polyphonic sounds) the control ROM has a size of 112K bits, RAM 445.4K bits and the control data/waveform ROM (for 100 timbres) 508K bits; one machine cycle is about 276 nanoseconds with a maximum number of cycles of the interrupt program when invoked being about 150; and the executing period of the interrupting process (tone output sampling period) is about 47 microseconds." Expressed in KBytes this would mean 55.7KB RAM, 14KB program ROM and 63.5KB sound ROM, which isn't far away from a Commodore C64 with large ROM cartridge. Said CPU speed would be about 3.6 MIPS. Higher grade MIDI keyboards like MT-240, MT-540 or MT-750 certainly have sub-CPU cores for 16 bit sound generation. Their external ROM is 512KB up to 1MB. Interesting is that OKI made a general midi sound IC ML2860 (32 note polyphonic ADPCM) to play high quality ring tones in mobile phones, but the datasheet from 2002 contains a very strange note: "Please appreciate that ML2860 is not offered for musical instrument and toy applications, such as keyboards." This suggests that OKI licensed an efficient sound synthesis engine (possibly even surplus ICs) from Casio keyboards, but had to sign an agreement not to use it in competitive products against Casio. - Does anybody know more about this sound engine?

On eBay I had bought parts of a Casio Symphonytron. I don't own the entire stage organ system but only one CT-8000, the RC-1 accompaniment/drum machine and a defective MB-1 sequencer in very beaten up condition (full of scratches, dirt and glue residues), but no pedal board. It came without the CIDI (Casio's Infernal/Inferior/Internal/Instrument Digital Interface) cables, so I ordered 3 DIN14 cables for Atari ST floppy, those work perfectly with the RC-1 (with one keyboard it does key split accompaniment with arpeggio, and also the trio mode works). Like with Kawai MS20, when you set a preset sound on the keyboard it plays a short fanfare with it (always the same notes). How ever my MB-1 doesn't work at all (buttons don't respond and it makes sometimes a louder growing digital buzz); possibly the eprom is dead. Also CT-8000 and RC-1 contain (as the only Casio instruments I know) each a soldered eprom; I backed up all 3 to avoid data loss. Unfortunately my Symphonytron sequencer unit MB-1 is dead (does nothing, but plays note mess when touching the crystal etc.), so I am not sure if its eprom may have failed (dump does not change by reducing Vcc) or it might be still a bug by the lack of original CIDI port cables. - hardware details I have photographed all my Symphonytron PCBs from both sides. The multi-chip hardware is quite complex and particularly the RC-1 and MB-1 have several stacked PCBs in their crowded case. Fortunately there are are some pinout marks on them, those may help to decipher them. The MB-1 and CT-8000 both have the same CPU "NEC D8049C 364" (Intel MCS-48, I dumped its firmware) with sound IC "D931C 011". The RC-1 CPU is a "NEC D930G 011". So they are far relatives of the Casio CT-410V (MT-65) hardware class (minus the VCA, but with external ROM) which may help to research hidden functions of its chip set. I don't own the FK-1 pedal board, so I have no clue what is inside. Did you know that early Casio keyboards had a CPU compatible with Intel 8049? Unfortunately the "Willem Pro4 isp" eprommer had a way too weak power supply with tiny SMD transistors switching the voltages. One was burnt anyway, so I had to install bigger non-SMD ones to get the MCS-48 adapter to work. Casio "D8049C xxx" ICs need Vcc of at least 4.5V to read properly, which was impossible with the original transistors ans PSU (it gave only 4V even in 5.6V mode). I installed a 10kOhm resistor into the EA line to avoid damage by the +12V if the IC would not have supported it properly, and connected it to a 5kOhm potentiometer to vary the voltage, which I didn't need. (Too high EA voltage (15V) outputs only "00" while too low voltage (9V?) makes the CPU run its program and output garbage. At too low Vcc it repeats the first part of the rom again and again.) So I e.g. could read the firmware of the Symphonytron Casio CT-8000 cpu and Casio HT-6000 synth (its D80C48 seems to be a real CMOS IC that draws less current). Also MT-36,MT-40,MT-90/MT-200 and Casiotone 401 have such a CPU. - need service manual Eons ago I downloaded the complete Symphonytron user manual from an eBay link, but I have no schematics. Has anybody a service manual? Particularly I am interested in the MB-1 hardware, the official CIDI cable wiring (may the MB-1 only need a crossed wire somewhere?) and the pedal board (has anybody dumped the eprom?).

Hello, I am collector of music keyboards and electronic sound toys and partly modify them into synthesizers. This is my keyboard site: http://weltenschule.de/TableHooters/index.html I bought an eprommer ("Willem PRO4 isp",had unfortunately defective transistors and other flaws I had to fix) and have started to dump EPROMs and ROMs of my keyboard collection. - Has anybody tried yet to make an emulator (similar like MAME) for old Casio keyboards? E.g. Casiotone 401 and MT-40 are controlled by an Intel MCS-48 microcontroller which ROM I successfully dumped. So at least the accompaniment section would be possible to emulate yet. Robin Whittle (firstpr.com) found out much about the Consonant-Vowel synthesis main voice sound ICs in early Casios, which would be useful to emulate them. Also the various Casio calculator emulators on the internet might be useful to understand what kinds of special CPUs Casio has used. Google patent search helped much to get an idea what is going on inside of them. Unfortunately most early main ICs seem to be rather based on general digital logics (networks of gates, counters and flipflops - like a Pong game) than a CPU (software controlled by one central code ROM) in its stricter sense. I am still working on documenting the pinouts and functions (e.g. key matrix eastereggs) of all 1980th Casio home keyboard special ICs. For this I already have examined all service manuals I could find on free websites. Unfortunately there aren't many about first generation Casios. (If you need info, e-mail me.) I also own a dead SK-200 (from eBay,someone elses circuit-bending-corpse); after disabling the auto-power-off (to make it turn on),only all lights flicker wildly and there is some bus activity (seen on CRT oscilloscope), but it makes no sound at all. Does anybody know the symptom? Is the sound CPU dead?

New files re-uploaded: Casio Symphonytron 8000 manual I have re-uploaded the manual of the ultra-rare "Casio Symphonytron 8000" stage organ system. It is describing all components and even a smaller setup with only one CT-8000 keyboard (much like mine). These PDF files are 10 and 15MB huge, so I placed them on a file hoster that claims to keep them (hopefully) for 1 year. Casio Symphonytron 8000 brochure: https://www.file-upload.net/download-15021277/Symphonytron8000-brochure-engl.pdf.html Casio Symphonytron 8000 German manual: https://www.file-upload.net/download-15021276/symphonytron-DE.pdf.html