RE: Multi-ROM built, what now?

From: Baltissen, GJPAA (Ruud) <ruud.baltissen_at_apg.nl>
Date: Thu, 6 Jun 2013 06:48:08 +0000
Message-ID: <54F350D2C6501448A3EE14B7854C5FB508FD23D5@WSV10441N3.office01.internalcorp.net>
Hallo Mike,
 

> A bank-switched ROM could be used to enhance JiffyDOS 64:.....

Great ideas!



Hallo Pete,


> It would be nice to be able to reconfigure a flash device than
> burn EPROMs, ...

The idea was indeed to be able to write FlashRAMs. That's why I asked here on the list how it could be done some time ago.



Hallo Micha,


> It is working right now but requires access to the BASIC ROM
> for reprogramming, ...

I don't understand that, please explain.


On a VIC-20 one can write to the ROM, on my expanded VIC-2o the GAL takes care of disabling writing to the FlashRAM. It starts up with a menu enabling you to choose the needed ROMs. The menu will also enable you to reprogram the FlashRAM. It will copy the program doing that job to RAM, will ask for what bank has to be programmed, what data to be loaded from disk (or catridge or other sources) and start the job. FYI: in my case a switch takes care of write-protecting the FlashRAM. But I'm thinking about using another free pin of the extra 6522.

On the C64 writing to the ROM in reality means writing to the RAM under the ROM. So it will require a bit more ingenious hardware to overcome this problem. IMHO a simple trick is tapping the CASRAM signal and combining it with an address decoder. So data written to the "ROM" will be written to the FlashRAM as well.


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Received on 2013-06-06 07:00:04

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