SY99

New baby at home : 

Fully functionnal.

Some switchs need top be replaced as well as the backlighting of the display.
Nothing difficult.

Yep!

SRAM select command Ver 1.0

The circuit for the selection of the sixteen SRAM bank is done.

This system is able to select the sixteen 2Kb equivalent space memory of my auto-saved memory :

To reach this goal, I used a totally new microcontroller for me and Chinees brand. This microcontroller is unlike any of those known in Europe or the USA. But I like testing new solutions... To work with this new I.C., there is an emulator that can be used to prototype the concept :

As usual, when the program 'looks' good, it's time to burn the software into the microcontroller. This microcontroller is not in-circuit programmable and does not offer the in-circuit emulation. It's a little limitation to its use, especially for complex systems. But the emulator supports the real-time mode. In the same way, the programmer does not allow to directly burn the type of microcontroller used, it is necessary to make a small assembly :

But, again, it works very well :

Once the program is written into the microcontroller, it remains only to solder it on the final board and to test the final assembly :

The system works perfectly and I was able to test the access to all the banks in the memory, thanks to the use of the test mode of the Mini-Pro 'universal' programmer.

Now, the next step is to install the complete system into the JX-8P, for example...

M.I.D.I. MERGE 'HUB'.

An other project in progress :

M.I.D.I. MERGE HUB

• Easy to use two input merged ports towards six output ports.
• One output replica port for one of the input port. 
• Small form factor with 3,5mm jack connectors.
• Single USB mini power port.

M.I.D.I. to CV/GATE

An other project in progress :

M.I.D.I. to CV/GATE interface

• M.I.D.I. channels : 1 to 8 OR 9 to 16.
• GATE : 5V.
• CV : 4 x (0V to 5V) and 4 x (0V to 10V).
• CONNECTOR : 3,5mm jacks.

SRAM select command.

My system of SRAM bank selection in on the way...

This system selects one of the memory banks installed inside a synthesizer. It will remain outside the synthesizer and will be connected to the internal memory using a connector placed on the instrument case.

In addition, a MIDI connection will allow the automatic selection of the bank, in relation to the desired patch. So it will not be necessary to modify the synthesizer motherboard in any way.

This system makes it possible to manually modify the memory bank, as well as the MIDI channel for receiving the MIDI bank change information. The MIDI channel and the number of the last bank used will be saved.

this system should also be a better bank change solution for my Prophet VS, compared to the previous system :

THE NEWS

This last month, two prototypes were made. A circuit compatible with the 16550 UART and a self-saved 16 x 6116 SRAM circuit :

The 16550 compatible UART is partially tested. Its usb interface is fully functional. This '16550' offers two identical serial interfaces. One of them can be used in TTL or with a RS232C level converters as usual, the other is directly connected to the on board USB interface. It would be easier to communicate to vintage computer with this solution, as with my hold Z80 N8VEM board : 

On my N8VEM I haven't yet the 1,8432MHz oscillator, as in this picture.

The 16 x 6116 equivalent self-saved SRAM is tested. It's basically the same system as my previous self-saved 6116 solution : 

the hold version.

BUT, now it's possible to select ALL the sixteen 2Kb space. I work on an easy-to-use bank selector...

16 banks of internal 2Kb auto-backuped SRAM.

And now, the equivalent of 16 x 6116 auto-saved memories for your favorite vintage machine like :

• Alpha Juno 1-2
• Juno 106
• JX-3P
• MKS-30
• JX-8P
• JP-6
• TR707
• Prophet 600
• DW6000
• DW8000

and many others...

On the past, I developed a simple solution that had the disadvantage of only using part of the new memory component:

Very effective solution, for example inside a Roland JX-8P :

But, only 2Kb are used on the 32Kb that contains the new RAM.

So I decided to do a new version with an additionnal connector for the extra addresses selection :

The J1 connector will allow to select the memory bank using an external selection solution.

The other side of the board :

This board will be a little bigger than the previous version but still very closed to the original size of a 6116 SRAM chip :

Once this card will have been tested, it will remain to develop the board of the memory banks selection system.