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SpidersWeb
March 10th, 2016, 02:51 PM
Started diagnosing another DTK turbo clone, and wanted to make a thread for my stupid questions :)

My first question is regarding the ROM setup. These boards (I have 3) allow you to configure the ROM for 2764 or 27128 or 27256 by moving/soldering a chip socket. My others are all set for 27256 and just have a single 32KB chip installed, however this one has five (not four) 2764's labelled 2,3,4,5,6, and 7. There is sockets for ROM 0 and ROM 1 too but they're not installed.

In the 27256 units, the boot ROM goes in the "ROM7" socket.

I haven't had a chance to read the ROMs yet, but any ideas on why there is 5 rather than 4?
Which ROM socket is most likely the ideal place for a single 2764 diag ROM? ROM 2,3,7?

Just after people's thoughts.

modem7
March 10th, 2016, 04:22 PM
Is this the DTK motherboard shown at [here (http://www.minuszerodegrees.net/xt_clone_bios/X'Golden%20Board%20of%20revision%20G.jpg)] ?

SpidersWeb
March 10th, 2016, 06:50 PM
Is this the DTK motherboard shown at [here (http://www.minuszerodegrees.net/xt_clone_bios/X'Golden%20Board%20of%20revision%20G.jpg)] ?

It is identical, except I don't have the first 3 ROM sockets, and my ROM chips themselves are labelled in reverse order as "3,4,5,6,7" [not that it probably matters].
Every chip is socketed which is awesome, it has had battery damage from a leaky RTC etc - so there will be lots to do - just curious about the ROM layout.

Have I misidentified it as DTK, or it actually a DTK X Golden Board?

modem7
March 10th, 2016, 07:06 PM
It is identical, except I don't have the first 3 ROM sockets, and my ROM chips themselves are labelled in reverse order as "3,4,5,6,7" [not that it probably matters].
So, one BIOS ROM and four ROMs for the BASIC.


Have I misidentified it as DTK, or it actually a DTK X Golden Board?
I think we both have misidentified it as DTK. As soon as I read your description of the board, I thought to myself, "I know that board", then in my reply, I accidentally added "DTK".

SpidersWeb
March 10th, 2016, 08:34 PM
Cheers for that, nice detective work, I probably would've never noticed.

I just went over it again and on mine there is actually no branding whatsoever, but other than that the silkscreen / jumpers / layout / every chip being socketed is identical.
I'll be curious to see what BIOS mine has, the brand name on the case is "Pronix" but I assumed that was just a generic dime-a-dozen name.

Trying to find my IC tester, and my EPROM reader/writer again - then I'll probably have more interesting things to discuss. We have been repainting the house, so my gear is all over the place.

Board is a non-starter, mild battery corrosion from an RTC card. Has CLK and the address lines are lighting up [and go away when CPU is removed] but that's all I've confirmed.

modem7
March 10th, 2016, 08:39 PM
Trying to find my IC tester, and my EPROM reader/writer again - then I'll probably have more interesting things to discuss.
You may find that the four BASIC ROMs are just copies of the four BASIC ROMs found in the IBM 5150.

Chuck(G)
March 11th, 2016, 09:26 AM
That would be my guess--I've got a similarly-equipped Taiwanese XT clone--except that I equipped it myself back in the day.

8088 XT-type clones are a mixed lot--almost all derive from the basic ERSO designs--and some even have ERSO-branded BIOSes.

SpidersWeb
March 14th, 2016, 09:51 PM
Wow, I just read ROM7, these guys had no shame at all.
It's the 08/16/82 BIOS from the IBM 5160 PC XT - no changes, not even the COPR IBM at the top!