Re: Mouse card --- Can EPROM go Bad?

[Patrick Schaefer <pa.schaefer@fz-juelich.de>]

Rubywand wrote:

>       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.

My Apple ][ plus boards have mask ROMs, my //e's all use OTP EPROMs.
Mask ROMs were only seldom used after 1980.

> > 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.

I have uploaded some ROM images to
ftp://apple.cabi.net/pub/apple_ii/incoming/romimage.zip. Perhaps the
sysop could create a directory for them, so the access would be easier.
I have also uploaded a schematic diagram of the Sider interface card.

>      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.

Apple used such proms in the beginning, they had names like P1 (on the
Parallel card) or P5A, P6A (on the Disk II controller). Most of them are
of the TI 28LS22 or MMI 6301 type, they are rather safe. 


Patrick