defor
New Member
Posts: 1
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Post by defor on Feb 5, 2005 11:00:44 GMT -5
Finally got my hands on a few units from KB toys today.. anyway, that's not the point...
Comparing some of the images, my units, etc... there seem to be some models with blob-based ram, and others with tsop ram units.... other differences abound also between the schematics and the actual unit, in both actual hardware present and the silkscreened labels. Have there been any revisions to this schematic?
On that topic.. I was interested in how the addon rom is enabled. My thought is that cutting ROMCS will disable the system from recognizing the external rom ... can someone verify this theory, and in turn, possibly trace this on the board.
Thanks! -Dan
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Post by NetSamurai on Feb 9, 2005 1:31:13 GMT -5
Cutting the ROMCS line should in fact disable the built-in ROM. It will, however, render the unit useless unless you attach your own ROM with the kernel and basic in the proper places. The ROMCS line starts on the silkscreen side with a via in the middle of the FIRE1 label. It goes from there to the ROM itself. Check out home.comcast.net/~netsamurai/rom_pins_enhanced.jpg for more info. Scott McDonnell
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Post by NetSamurai on Feb 9, 2005 1:34:15 GMT -5
Oops, hit send too soon. About your first question. Yes, the schematic on the web is not the production level schematic, but very close to it. Only minor changes should be present.
There are different units using different components as you have noticed (I have found 3 variations) and I have also found 2 different board versions (traces are laid out a little differently.)
Scott McDonnell
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Post by robthecat on Mar 9, 2005 19:27:10 GMT -5
Correct me if I´am wrong ??!!
The Idea: CPU Asic reads Datas from Rom (under Epoxy) and writes it to the RAM area.Here we could modify it ;D
I think it must be possible to solder some wires on the 128 KB Ram ic adressbus and Data. Then you Solder an 128kb Eprom with your program on this wires.
you cut the RamOE wire on the Board and put it on a switch.
With this switch you can Enable RAM Read Access or Rom OE.
So it is possible to have your own Kernal System. With this you can boot from IEC Bus anything you want.
The first the Kernal do, is to copy some parts to the Ram that lies under the ROM. Second you put a message on screen "Toggle Switch" so you go straight to RAM Area and starts your Loader or something Else.
Regards
Robert Dupres Vienna / Austria
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