Strange Character ROM connection

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Strange Character ROM connection

I've recently restored this Apple II+ Clone. It has a UM2316 as character ROM. The Chip itself is replaceable with a 2716 eprom. But none of the standard Apple II Character ROMs works.

The connection between the ROM and the 74166 totally diffrent from what it is in a regular II+.

Does anyone regognize this board? Are there any Informations / ROM images available anywhere?

 

 

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Image icon Apple II+ Clone (Unicom)2.27 MB
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I've got one that is similar,

I've got one that is similar, but not exactly the same.  This one appears to use 2732 EPROMs for example where the one I have uses 2716.  Mine has the 74LS138 that is non-populated on this mobo, and mine has the inline power connector populated instead of the 2x3 connector.  There were a lot of variations on these.  I believe most of them originated out of either Tiawan or Hong Kong back in the day, although I know they made some clones in place like Brazil as well.  As for the variation of the CHARGEN EPROM, that is interesting.  Have you done a dump of the data, or is your EPROM bad?  I've been working on a project for the //e using a larger ROM and the annunciator outputs from the game port to allow software selection of CHARGEN images, so I've been working on a CHARGEN image editor to facilitate making new "fonts".  I haven't gotten that far on it yet.  Too many other projects ahead of it at the moment.

 

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The chargen ROM works, if you

The chargen ROM works, if you like, you can have a dump of it.

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The one in my clone seems to

The one in my clone seems to work.  I have a MiniPro TL866CS programmer so I can dump or duplicate EPROMs.

 

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When you say it doesnt work,

When you say it doesnt work, what is it not doing?

Post a photo of the screen. It may not be a CG ROM problem at all.

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softwarejanitor wrote:I have

softwarejanitor wrote:

I have a MiniPro TL866CS programmer so I can dump or duplicate EPROMs.

 

This chinese programmer cannot program EPROMs with Vpp @ 25V. Nearly all (old) 2716 and most (old) 2732 are of this type.

And a warning: the data base is very poor. Many other EPROMs have different voltages for programming or supply during programming. I compared several datasheets to the data base.

 

Regards,

Ralf

 

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I've not had a problem with

I've not had a problem with any of the 2716 to 27512 that I have tried, but perhaps they are all newer.  Most of the ones I have bought recently have been ST, but I've burned AMD and Intel fabbed parts from my 30 year old stash w/o issues too.

 

I'm also not using the supplied software, but rather an open source one because I don't have Windows, so I am not sure it uses the same database.

 

 

 

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