J.B. Wood wrote:
> On 08/17/2016 08:07 AM, frank wrote:
>
> Hello, and I screwed up on my OP. I should've said "Quick Brown Box".
> Back when these were on the market IIRC although the internal backup
> battery would last a while it wasn't easily replaced. So these weren't
> flash-based. I think the carts also came with a word processor. Turns
> out Googling on some non-usenet Commodore forums reveals that the topic
> has been addressed. Someone even had a schematic shown.
Ok, now I see the ones :)
They're originally SRAM based. I did a few projects with those kind of
SRAM chips and when in standby mode, they run with more or less (often quite
less) than 1 uA from a 3V battery. This makes quite a long battery run.
Depends on how often you power the cartdrige up or leave it powered down.
A few months backup from a little 3V lithium battery is very possible.
>
> Come to think of it a better way would be to incorporate flash memory
> that, like a USB flash drive, could be plugged into the ROM
> expansion/game port. Thanks for the quick reply. Sincerely,
well, this isn't so easy instead, flash chips have typical byte write cycle
of 10ms, while write cycle on C64 bus is 0.5us (roughly).
You can write them but you need a special program that waits for write
completion before writing different pages.
A much better option would be using ferro-electric RAMs or magneto-resistive
RAMs, both don't need any backup power, can be written and read like normal
SRAM and they keep the content forever.
The only downside is the cost, one 256kbit chip costs more than 6 euros,
that makes less attractive to develop such a solution because one cartdrige
with this chip (256kbit = 32KBytes) would cost more than 20 euros.
If enough people are interested, I can make a better estimate and
a complete design.
Frank IZ8DWF
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