Re: FLASH ROM replacement

Re: FLASH ROM replacement

From: Nate Lawson <>
Date: Sun, 03 May 2009 16:20:29 -0700
Message-ID: <>
Bil Herd wrote:
> My apologies for that, habit from the old days.
> So I jumped in without really knowing the application or what the challenges
> were, I assumed it was a "how to connect to something inside of something"
> type problem if you were to replace an internal eprom with a reprogrammable
> part and didn't want wires snaking out through the vent holes.
> What kind of app is this targeting?  Cartridge, C64, or damm near anything?
> Is it a matter of getting hold of the R/W line and the host can participate
> in the reprogramming? 
> Can the host be put into tristate reliably and something grab the buses, for
> example a 24 bit shift register driven by 2/3 wire? (Let the programmer do
> all of the magic byte stuff, the adapter just s/p translates).  Twice the
> pins if you have to mux.
> I assume that anything that adds price at all is out of the range, you'd be
> looking a pin count for the address and data lines at a minimum price,
> whether done with TTLish shift registers or PAL/PGA/uProc.

There's quite a lot of SPI flash, although I don't see why he needs high
capacity or clock rate to support the replacement ROM application.

Flash is a pretty easy state machine and x8 parts mean you could
probably do it with 2 shift registers. I haven't thought of the
fewest-parts approach though.

> Too bad there isn't an AVR type with 512k flash. you think your talking to a
> mem, your really talking to a proc.

The ST Micro STM32 series has up to 512k flash but is expensive compared
to flash alone.


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Received on 2009-05-04 01:26:50

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