We love classic synthesizers here at Hackaday. So does [gligli], but he didn’t like the processor limitations of the Prophet 600. That’s why he’s given it a new brain in the form of a Teensy++. The Sequential Circuits Prophet 600 was a big deal when it was released back in 1982/1983. The 600 was the first commercially available synthesizer to include a MIDI interface. The original design of the 600 could be called a hybrid. A Zilog Z80 microprocessor controlled modular analog voice chips. The Z80 was a bit stressed in this configuration though, and a few limitations were evident. An 8 bit processor just wasn’t quite enough for software driven envelopes and a Low Frequency Oscillator (LFO) control. This was further exacerbated by the fact that everything was driven through a 14 bit DAC.
[gligli] discovered most of the limitations in the 600 were due to the processor. By beefing up the processing power he could really unlock the potential within 600. Since he didn’t actually have a Prophet 600, he started with the schematic. [gligli] created a PC based emulator for the digital circuits, learning the whole system as he worked. With that phase complete, [gligli] bought a used Prophet and started hacking. The Teensy++ required a few hardware mods to fill the Z80’s shoes, including cutting off a pin and adding a few jumper wires. We really like the fact that no changes to the Prophet 600 itself are required. Pull out the Teensy++, drop in the Z80, and you’re ready to party like it’s 1982 again.
The new processor interfaces directly with the Z80’s 8 bit bus. Since the AVR on the Teensy has built-in RAM and ROM, it simply ignores the ROM and RAM address spaces of the original system. Interfacing a fast micro with older parts like an 8253 timer and a 68B50 UART does have its pitfalls though. The system bus had to run slow enough to not violate timing requirements of the various peripheral chips. To handle this, [gligli] added a number of wait statements in his firmware. Once the system was working, [gligli] was free to start adding new features. He began by smoothing out the stepped envelope and filter generators, as well as adding new exponential modes. From there he added new keyboard polyphony modes as well as pitch and mod wheel changes. The full lineup of new features are listed in the instruction manual (PDF link). Since this is an open source project, adding a feature is as simple as cracking open your favorite editor and writing it up.
Continue reading “Prophet 600: A Classic Synthesizer Gets Processor Upgrade”
Cheap FPGA boards are readily available, as are VHDL implementations of classic CPUs like the 6502, 6809, and Z80. Up until now, we haven’t seen anyone take these two parts and combine them into a complete system that turns an FPGA board into a complete 8-bit retrocomputer. Thanks to [Grant]’s work, it’s now possible to do just that (server on fire, here’s a google cache) with a $30 FPGA board and a handful of parts.
In its full configuration, the Multicomp, as [Grant] calls his project, includes either a 6502, 6809, Z80, or (in the future) a 6800 CPU. Video options include either monochrome RCA, RGB VGA, or RGB via SCART. This, along an SD card interface, a PS2 keyboard, and the ability to connect an external 128kB RAM chip (64k available) means it’s a piece of cake to build a proper and complete portable retrocomputer.
What’s extremely interesting about [Grant]’s project is the fact the data and address lines are fully exposed on the FPGA board. This means it’s possible to add whatever circuit you’d like to whatever retrocomputer you can imagine; if you want a few NES gamepads, an IDE interface, or you’d like to design your own primitive video card, it’s just a matter of designing a circuit and writing some assembly.
If you’d like to build your own, search “EP2C5T144C8N” on the usual sites, grab a few resistors and connectors, and take a look at [Grant]’s documentation and upcoming examples.
Via 6502.org forums
[Moogle] wrote in to see if anyone can figure out why his unused electrolytic capacitors are popping. This is the behavior you see in populated caps whose electrolyte dries out. But these are still in his parts bin. Anyone know why they would pop when going unused?
We see a lot of BIOS flashing hacks; but it’s always a handy thing to know about when you get in a bind. Here [Adan] shows us how to reflash a corrupt BIOS using a Tiva C Launchpad board.
Wanting to hack together her own blow gun [Carlyn] scrapped a handheld vacuum cleaner. When she discovered the pump could not easily be converted from suck to blow she made a handheld suction manipulator which picks up paper plates and a few slightly heavier objects.
Unfortunately a drill press is not one of the tools we have in our lair right now. If we did, this tip about using it to help tap threads in a hole would come in really hand.
Retro computing fans will appreciate this Z80 computer build (translated). It’s a fairly large mainboard with plenty of chips, resistors, buttons, and seven segment displays. Excellent. [Thanks Daniel]
We start to drool a little bit when we see a teardown post that shows off a piece of equipment really well. We’ve already reached for a bib to catch the slobber from pawing our way through [David’s] teardown of an HP 6010A bench supply.
“I’m sorry Dave, I’m afraid I can’t open the dorm room door.” Does your dorm room have a peephole? Take [pjensen’s] lead and turn it into a mini HAL 9000 using a red LED.
Mix a little work in with your hobby skills. [Vittore] needed to build a video looper to drive some TV screens for a Hotel contract job. He grabbed a Raspberry Pi and got to work. The final product (translated) even uses a shared folder on the hotel’s network as the source slides.
We’re not sure if anyone noticed last Monday (it was Labor Day in the U.S.). We had a little fun with coffee themed posts. [Tom] wrote in to remind us about the HTCPCP: Hyper Text Coffee Pot Control Protocol. If you don’t have time to read it all, he suggests you don’t miss his favorite, error code 418.
Maybe funny reading isn’t your thing right now, but we have some more helpful stuff to offer. Check out [John Chandler’s] Commandments for using PIC microcontrollers from a few years back.
[Andy] has some old smart phones which he is using in his projects. His beef with the touchscreens is that there’s no tactile feedback. Since these are going to be dedicated displays he’s outlining the touch controls with tape to let your finger know what it’s doing.
If you’re living in your first home in America there’s a really good chance it’s a 1950’s ranch house considering how many of them were built after World War II. Bring its infrastructure into the information age with a cable retrofit. [Andrew Rossignol] just did so and posted a lot of pictures of the process.
If you liked [Ken Shirriff’s] post about the Sinclair Scientific Calculator we think you’ll love his continuation of a Z80 reverse engineering series.
The members of Shackspace got their hands on an antiquated robot arm. It’s a Mitsubishi Movemaster RM-101 and was probably manufactured in the mid 1980’s. There’s almost nothing out there that tells you how to use the thing, and so they set out to figure out how to control the hardware.
This is a great example of how an EPROM dump can be really useful. After further inspection the team discovered that the arm is driven by a Z80 processor whose program is stored on an EPROM. The first thing the guys did was dump the memory since the aging storage will be useless if just a few bits become degraded. This dump will be really useful for others whose chip has already given up the ghost. The data from that dump was disassembled and painstakingly pawed through to figure out what commands were being sent to the arm. This technique worked, as the team was able to re-implement the control protocol and has already used the arm for some light painting and pen plotting (seen above). After the break you can see a control demonstration.
Continue reading “Salvaged robot arm used for light painting and pen plotting”
[Alexis] sent in a single board computer he’s been working on. The project goal of his build was making it easily reproducible. From looking at the schematics, it’s one of the simplest fully-functional computers we’ve seen. The build runs CP/M 2.2 off of two 3.5 inch floppies. This opens up a lot of options as to what software is already available. Although it operates over a serial terminal, [Alexis] pretty much duplicated an Osborne I, only at double the speed.
[Alexis] got a little e-fame from his earlier 8088 homebrew computer built from very early 8088’s rescued from an electronics junk shop. These 8088 computers made the blog rounds by playing Still Alive with a SID chip from a Commodore 64 and a YM2151 FM synth chip.
For now, I guess we’ll have to settle for a video of [Alexis]’ Z80 computer running CP/M. Check out a video after the break of his computer running the greatest Infocom adventure, Hitchhiker’s Guide to the Galaxy.
Continue reading “Easy to build Z80 single board computer”
If you are a frequent reader, you are undoubtedly familiar with hacker [Sprite_tm]. He has been working with fellow members of the TkkrLab hackerspace to get things ready for their official grand opening on May 28th, and wrote in to share a project he recently completed to kick things off.
As part of their preparations, they have been stocking the joint with all sorts of hacker-friendly goodies including plenty of tools and Club Mate, as well as a vintage ‘1943’ arcade cabinet. The game is a group favorite, though every time the power is turned off, it loses all of the hard-earned high scores. [Sprite_tm] knew he could improve on the current paper-based score register, so he pulled the machine open to see what could be done.
He used an AVR to tap into the machine’s Z80 logic board, allowing him to read and write to the entirety of the game’s RAM whenever he pleased. This enabled him to keep tabs on the high scores, restoring them to memory whenever the machine is powered back on. The addition of the AVR also allowed him to add a TCP/IP interface, which is used to send high scores to Twitter whenever someone beats the previous record.
His modular bus tap can be used in all sorts of Z80-based hardware, so if you have some vintage equipment laying around, be sure to swing by his site for a more detailed look at the build process.