test

You should wire the pins to DPDT switches with the center pole attached to the pin and the two poles going to a pull up resistor to +5 and the other to Ground. So when the switch is toggle in either direction the pin is either toggled to high or low state.

This will allow you to divide the EPROM into Banks of the original ROMs size. You can then load up to the number of Banks this breaks the ROM up into. With three pins being toggled thats 8 Banks.

Here is some info on how i did this for my HR-16. The table is all the math for the banking with some color coding for groupings. There is also a schematic for how the chip was wired to make this all work.

I hope that gets you on the right path,

Jesse

From: krikor kouchian <krikorola@...>
To: "tr-707@yahoogroups.com" <tr-707@yahoogroups.com>
Sent: Monday, February 25, 2013 3:20 PM
Subject: Re: [tr-707] TR-707 with 27C4001 EPROM

hello,
i'm curious about this modification.
where did you find info about it
i did a similar mod on a RZ1 but i'd be interested to do it to a 707.
best
K

Le lundi 25 février 2013, swekompatibel < swekompatibel@... > a écrit :

>
>
> Hello!
>
> I have made the custom rom mod to my Roland TR-707 and now i want to use a 27C4001 EPROM and switch banks with a DIP-switch.
>
> Please would you help me, Adress A16 A17 A18 goes separeted to the DIP switch, but what should i connect the other side of the DIP-switch, Ground A15 .
>
> And how should i program the chip, switch banks with the DIP and program 8 times with 8 separated rom binaries no
>
> Kind regards and thaks in advance!
>
> Johan
>
>

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1250 Re: [tr-707] TR-707 with 27C4001 EPROM