Subject: Re: Mouse card --- Can EPROM go Bad?
From: Rubywand <rubywand@swbell.net>
Date: Tue, Nov 24, 1998 1s5amBs
Message-id: <365A68C0.7298D09@swbell.net>

Supertimer writes ...
> 
> Rubywand <rubywand@swbell.net> wrote:
> 
> >     It seems like a good idea to start archiving ROMs and PROMs used on
> >the Apple II motherboards and cards like RamFAST. (A prommer can read
> >the contents which can be stored on disk.)  When ROMs start to crater,
> >users could get a PROM replacement without a lot of hassle.
> 
> Are the Apple IIGS motherboard ROM(s) programmed like this?
>

     A check of some old IC manuals indicates three options in a typical
firmware development cycle. The smallest scale run would be done on
EPROM by the company or developer. For medium-scale runs of tested
material, the firmware could be programmed into non-eraseable PROMs
(e.g. PROMs without an erase window. For large-scale runs, the firmware
would be submitted to an IC maker, a mask prepared, and ROMs would be
created by the IC maker.

      The 'mask-programmed' ROMs seem to be a good deal more durable and
less forgetful than eraseable or non-reaseable PROMs. In large
quantities, this also appears to be the cheapest way to go. So, it seems
likely that Apple's motherboard ROMs are not going to crater any time
soon.

 
> How about a csa2 effort to make a list of the ROMs that will crater
> so that we can start archiving them on CD-ROMs.
>
> The list should also include the type of EPROM that can be used
> as a replacement and where to buy the programmers.
>

     Sounds like a good idea. Mainly, any EPROM should be read-out and
archived. Large MOS PROMs seem like good candidates, too.

     I do not know if any Apple boards use bipolar PROMs of the kind
where you blow fuses to do the programming. Probably, these and
mask-programmed ROMs are low risks for going bad in the next few years.
Still, having all firmware backed up in an archive couldn't hurt.      

 
> This is really sucks....I thought my Apple IIGS would last forever!

 ....

     Having firmware backed up somewhere will help guarantee that it
will.



Rubywand