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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 27th Jun 2013, 6:34 pm   #41
Alf Fisher
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Location: Potton, Bedfordshire, UK.
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Default Re: Maplin Z80 SBC

Hi Bazil2112,
Regarding the link in your post #39 this looks like the EPROM has been disassembled by some kind person. It could be re-assembled but there are no labels so not sure if that would cause a problem. If the other file is a pure binary, then I cant see what is in on this PC. The Maplin dot zip file has some Acorn files apart from some others that I havent worked out what they are for as yet.

Reference your post #22, I have found the magazines with the article on the Z80 SBC. In the one for the serial board GJ25C, there isn't an EPROM on that board. The only big chip on it is an 8251 USART. Not sure if I have misunderstood your posting.

Alf
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Old 28th Jun 2013, 11:28 am   #42
Bazil2112
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Default Re: Maplin Z80 SBC

Hi Alf,
As you know there were two roms for the sbc the first one was for the 7 segment display and keyboard, the other was for the serial interface, which was changed on the main board to run the serial interface, the one i sent you on the excel sreadsheet was from the original M12 for the keydoard/display, the one from the link above seems to be for the serial interface (I hope). The Maplin.zip file contains an install for the Z80 monitor program to connect the serial interface to a pc.

There is also an assembler program as well i found a link for this last night here i have installed both of these on my windows 7 pc and both run, all I have to do now is make up a serial cable, create an MS12 eprom, fit a new serial port, fit a new 7805 regulator (I removed the originals for another project) and then it should work, ha!
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Old 8th Jul 2013, 6:16 pm   #43
Alf Fisher
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Default Re: Maplin Z80 SBC

Hi Bazil2112,
I've emailed you links to enable you download the articles.

I had forgotten that there were two versions of the EPROM; one for the keypad interface using the 8279 chip and the other using the serial interface. Maybe that's the reason why I couldn't get it to work as I was using the wrong one!
I would like to get my CPU board working with the serial interface board but not sure which versions of EPROM contents I have and which I need.
Cheers,
Alf
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Old 9th Jul 2013, 8:40 pm   #44
SiriusHardware
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Default Re: Maplin Z80 SBC

Alf, in the archive linked to in message #20 of this thread there is a 2048-byte file with a filename ending in 'rom'. It's a raw binary file (not intel hex). Programme it into a 2716 eprom (choose 'binary' as the file type in your eprom programmer's software before loading in the code) and I suspect that you will then have in your hands the MS12 eprom.

As mentioned before, it may not do anything sensible without a PC running the companion software attached. However, I believe the same archive also contains that PC software. You may need a fairly old DOS or Windows computer to run it on.

Last edited by SiriusHardware; 9th Jul 2013 at 8:45 pm.
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Old 9th Jul 2013, 10:42 pm   #45
SiriusHardware
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Default Re: Maplin Z80 SBC

Quote:
Originally Posted by SiriusHardware View Post
You may need a fairly old DOS or Windows computer to run it on.
Too late to edit the above: From the installation instructions, it looks like it was made to run under Windows 3.1.
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Old 12th Jul 2013, 6:06 pm   #46
Alf Fisher
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Default Re: Maplin Z80 SBC

Hi SiriusHardware,
I downloaded and installed a HEX editor on the old laptop and opened the Maplinrom file, and found what you said was a binary file that looks to be Z80 code. Some way down the file, starting at address 0600H, there is a strange section of ASCII bytes that appear to be an advertisment or commercial for Tipper, a indie rock guitar band giving a phone number! No idea how that got in there or even supposed to be there!

Alf

Last edited by Alf Fisher; 12th Jul 2013 at 6:18 pm. Reason: Added start address of ASCII advert
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Old 14th Jul 2013, 11:43 pm   #47
SiriusHardware
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Default Re: Maplin Z80 SBC

Quote:
Originally Posted by Alf Fisher View Post
Hi SiriusHardware,
I downloaded and installed a HEX editor on the old laptop and opened the Maplinrom file, and found what you said was a binary file that looks to be Z80 code. Some way down the file, starting at address 0600H, there is a strange section of ASCII bytes that appear to be an advertisment or commercial for Tipper, a indie rock guitar band giving a phone number! No idea how that got in there or even supposed to be there!

Alf
I guess we now know what the author of the firmware did in his spare time!

That message wouldn't have been sanctioned by Maplin, so either the original author did put it in there unofficially or it has been added since by someone through whose hands the code has passed.

I think the same folder also contains a disassembly of the rom - if the disassembly does not contain that text then someone added the 'advert' at a later date. I might try googling them to see if they still exist.

Incidentally, the disassembly does contain labels - automatically generated ones created by the disassembler. For example, if it finds the code C3 09 09 (jump to 0909) then it creates a text label for the instruction at the destination address by adding 'L' to the front of the address. This is enough to allow an assembler to reassemble the code. Once you've worked out what the code does you can find / replace the machine generated label with one that means more to you.
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