Different ROMs for Lambda 8300

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mrtinb
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Re: Different ROMs for Lambda 8300

Post by mrtinb »

These are the ROMs for Lambda hardware I have found on Internet
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David G
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Re: Different ROMs for Lambda 8300

Post by David G »

Changes in RED (updated list)
These are the ROMs for Lambda hardware I have found on Internet
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mrtinb
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Re: Different ROMs for Lambda 8300

Post by mrtinb »

I know the files are the same. I was trying to tell, that the same ROM had different names. Somehow I wasn’t clear.
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Re: Different ROMs for Lambda 8300

Post by frankc64 »

Hello!
New on this list, as I just acquired a Lambda 8300.
I need to replace the ROM in a Lambda 8300. I tried to download the Lambda 8300 ROM LAM10061.BIN, but the link seems to be broken. Does anyone here have the ROM binary.

Best
Frank
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mrtinb
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Re: Different ROMs for Lambda 8300

Post by mrtinb »

http://web.archive.org/web/201612200322 ... M10061.BIN

As the Lambda 8300 uses masked ROM, you'll not be able to replace it with an EPROM or EEPROM without an adapter.
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Re: Different ROMs for Lambda 8300

Post by frankc64 »

Thanks!
Well, I guess that there is info about EPROM adaptors to be found on the web.
In the meantime I've come to suspect that my issue really has more to do with the 74LS05, as it looks like the data bus lines behave weird, while the address lines look normal.
/Frank
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1024MAK
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Re: Different ROMs for Lambda 8300

Post by 1024MAK »

It has to be said, mask ROM chips can occasionally fail, but most are fairly reliable. So it’s definitely worthwhile double checking and investigating other possible problems.

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mrtinb
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Re: Different ROMs for Lambda 8300

Post by mrtinb »

In the design of the ZX81 (which Lambda 8300 is a clone of), the ULA (glue logic IC) overrides data from for the CPU on the data bus. So the data bus signals does not look normal. However the signals are within specification to work.

This is explained in this video @6:30+ https://youtu.be/N9wEcpF-9-c
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Re: Different ROMs for Lambda 8300

Post by frankc64 »

Signal should be over 4V peak-to-peak, and that is the case on the address bus, but on the data bus they are less than 2V. That cannot be right.

/Frank
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Re: Different ROMs for Lambda 8300

Post by mrtinb »

I'm not an expert in electronics. The construction with the 74LS05 is different from the ZX81. My guess is that the 74LS05 is used to feed the NOP instruction into the data bus from the ULA. That might be wrong, as that would conflict always on the databus, as there is no resistors between the 75LS05 and databus towards the CPU.

Image
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