Intel 8048 in Jupiter 4 / Promars.

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Ohm's Law
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Intel 8048 in Jupiter 4 / Promars.

Post by Ohm's Law » Fri Mar 18, 2011 1:34 am

Hi,

After looking at my ProMars more i'm worried the CPU maybe dead.

Most pins are at +5VDC including the ABC output to the front-panel multiplexers inputs.

Any ideas of anything else to check? Crystal input is still there.

Did Roland use the rom in the Intel chip or an external? Can it be swapped?

A bit sad :cry:

Thanks,

Tim.
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OntarioHydro
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Re: Intel 8048 in Jupiter 4 / Promars.

Post by OntarioHydro » Fri Mar 18, 2011 2:33 am

these can be found in the keyboard of the Apple 2. You should be able to find one without too much trouble.
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Re: Intel 8048 in Jupiter 4 / Promars.

Post by cornutt » Fri Mar 18, 2011 5:46 am

The 8048 has 1K of mask ROM, but it is possible that the Promars does not use it. Given the relatively low production, Roland might not have wanted to spring for the cost of the masks for the ROM. If there's an EPROM somewhere on the board, it's probably not using the 8048 ROM.
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Re: Intel 8048 in Jupiter 4 / Promars.

Post by nathanscribe » Fri Mar 18, 2011 11:30 am

From what I remember, there are two CPUs in the Jupiter 4, one for memories and one for keybaord scanning etc. I'm hazarding a wild guess that the Promars shares this structure - which are we talking about? Also have a look at www.roland-jupiter.org, it's slow for a forum but there're a couple of Jupe specialists there including a chap who has reverse engineered the Jupe CPU and provides a retrofit kit with added features. He might be able to answer your questions.
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