[sdiy] PROM Replacement for Spider

[Raf Wlodarczyk]

The digiky ones come from Rochester and ALL the ones (i bought 50 of each type) I got from them were bad, partial writes, wouldnt clear etc.  I'll look at the AT27, thanks for the suggestion

> On 01/27/2026 11:26 AM EST Roman Sowa <modular at go2.pl> wrote:
> 
>  
> DigiKey has a thousand of them, but anyway, I wouldn't buy them because 
> of the price and age.
> Whenever I need to replace old EPROM I pick most common, cheapest and 
> easy to get OTP EPROM, which usually is AT27C256. It has 28 pins so 4 of 
> them will be outside of the socket, which typically can fit on the old 
> board without pushing other components. After programming just wire 5 
> pins together: 1,2,26,27,28
> 
> Or you may fance making breakout board for PLCC EPROM
> 
> forget about buying newly made EPROM smaller than 256kb
> 
> Roman
> 
> W dniu 2026-01-27 o 16:16, Raf Wlodarczyk pisze:
> > Hello list,
> > 
> > The supply of the IM6654 PROM i use in my Spider clone has dried up and was wondering if anyone had suggestions on how to use a modern part for a replacement.  IM6654 is a 8x512B device so could using a AT28C512 on an adapter do the trick?  My PROM/EEPROM knowledge is limited so any help would be greatly appreciated.
> > 
> > -R
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