Updating "Firm Ware" in an E.P.R.O.M ?

[SteveInOregon]

I have a vintage 23 channel CB ( CPI ) and I am acquiring another similar one (Palomar ) they both have a chip I guess its called an EPROM that is driven by software called "firm ware", both radios were purposefully made to be upgraded to 40 channels, as they were made just before the FCC allowed more channels so they were designed to ad more channels via programing in the very near future around 1977.

Hell if I know how to program a chip in an old radio to input 40 channels into the rig , how about You ?

Is anyone knowledgeable out this procedure out here ?

Thanks

[Sandbagger]

Mar 8, 2011 18:45:08 GMT -5 SteveInOregon said:

I have a vintage 23 channel CB ( CPI ) and I am acquiring another similar one (Palomar ) they both have a chip I guess its called an EPROM that is driven by software called "firm ware", both radios were purposefully made to be upgraded to 40 channels, as they were made just before the FCC allowed more channels so they were designed to ad more channels via programing in the very near future around 1977.

Hell if I know how to program a chip in an old radio to input 40 channels into the rig , how about You ?

Is anyone knowledgeable out this procedure out here ?

Thanks

There is no microprocessor in the CPI, so the EPROM does not contain an application program "firmware" per se. What the EPROM essentially does is perform a lookup table function, where it senses what is input by the channel selector switch(s) and outputs the proper binary word to program the PLL. The 40 channel (and up) mods are simply EPROM's which contin more combinations of channels (the original CPI's were made before the 40 channel bandplan was finalized and were ready for anywhere up to 99 channels based on the programming prom).

I would imagine that a very thorough search will turn up some information on how to program the EPROM, or where one could buy an already programmed part.

For someone familiar with how EPROMS work, they could make up a truth chart for how the rig works now, and should be able to extrapolate the programming for the upper frequencies.

[SteveInOregon]

My Search : I found a little gem here, a book from an old school cb'er all about modifying CB to 10m via EPROM programing.

There is a detailed section all about the Cobra 148 DX mod.

www.cbcintl.com/docs/CBEpromDataBook.pdf