IMPORTANT: Possible incompatibity issue with DK Remix board

[Sock Master]

This just happened so I don't have full verification or details yet, but it's possible that there may be a compatibility issue if your DK PCB has a certain variant of the Z80 chip.

I don't know if this is common or rare yet.  I have investigating to do.

If you have a Z80 chip labelled "NEC D780C" on your DK PCB, the Remix board may not function correctly.

The solution most likely is to switch the Z80 with a different one.  My DK PCB has a "SHARP LH0080A Z80A-CPU"

Basically, I think anything that ends with an "A" will be fine.  A Z80 chip with a number ending with a "C" might not be.


If people can check their DK PCBs to see how common a "C" type chip is, I would be extremely grateful.  (especially anyone who's already waiting for their board to arrive)

If it's common, I'm going to maybe include a Z80A with each Remix board but it's going to delay things.


I'm sorry everyone.  I'm going to do everything I can to fix this.

[Shnypz]

SHARP LH0080A Z80A-CPU over here

[danman123456]

Yeah it was odd but looking here not sure there is a big difference. Both are 4Mhz. Hopefully its some issue with the Z80c vs a.

http://www.cpu-world.com/Compare/346/NEC_Z80_4_MHz_(D780C-1)_vs_Sharp_Z80_4_MHz_(LH0080AH).html

Dan

[Sock Master]

I found a piece of hardware that had an NEC D780C in it and pulled the chip out.
It does the same thing that was happening to you when I tried it in the DK Remix board.

So that's pretty definitive.  Something is different with the D780C, something about it's signal timing I suspect.

I'm trying hardware & firmware tests to see if I can find some sort of solution to make it work properly, but no success yet.  For now it seems this chip is simply not compatible with the DK Remix board.

[f_symbols]

I just checked all 3 of my pcbs, all acquired from different sources at different times, and they all have the z80a; it's likely that this will be a very isolated occurrence.

[Scoundrl]

Manual specs z80a FWIW

[Sock Master]

It's probably something subtle as the C seems to work fine if I plug it into the DK board by itself.  I haven't been able to figure it out *yet*, but I have one to test now.

I ordered a few Z80A just in case someone will need one for/with their Remix board, but they probably won't arrive for a month.

[CrazyKongFan]

I've got 2 4-board PCB's. The one in my cocktail with the D2K board has a Sharp LH0080A, the spare one that partially works (CLK and VID boards both have issues, but the CPU board works fine) has an NEC Z80C. Looking at some of my other non-DK boards that use a Z80, there's mostly a mix of Sharp LH0080A's, NEC Z80C's and Zilog Z80A's. They probably used whatever they could get cheapest or was readily available when they were assembling boards.

[Simpsons99]

I know  I have 2 DK Board sets .. One Needs a Z80 Replaced on it ..  The chips you have spoken of are not on Ebay .

[tilt]

My pcb has a Sharp Z80-A

[Gettysburg1863]

Mine has the SHARP .....A

[danman123456]

I know  I have 2 DK Board sets .. One Needs a Z80 Replaced on it ..  The chips you have spoken of are not on Ebay .

Brian I ordered a Sharp Z80A on Ebay for $9.99 + $2.50 shipping from a us seller. There are tons of them on eBay

[Gettysburg1863]

My chip is installed (Remix only, no Deranged) and went in without a hitch, seated the entire way down. Works flawlessly. Thank you Sock, you rule!

[ChrisP]

Uh oh, bad news for ChrisP!

I knew there was a reason I decided to hang back and wait for the second round of these! 

Oh well, I'll pull out my Junior PCB, or my Popeye, and see if they'll work.

[f_symbols]

omg dat mad face doe