Another 4000-06 board

About original Memotech hardware.
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Crazyboss
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Re: Another 4000-06 board

Post by Crazyboss » 23 Jul 2015 14:27

Martin A wrote:t.

TI marked the data and address bus of the VDP backwards for some reason, so I _think_ it's the ram chip connected to AD3 and RD3 that needs looking at position 6F.
Thanks MARTIN I will try that later I have spare 4116, so will try to desolder the one at 6F and see if it works!
//CLAUS - Webmaster at www.mtxworld.dk

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1024MAK
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Re: Another 4000-06 board

Post by 1024MAK » 23 Jul 2015 21:07

Crazyboss wrote:Is it possible to get a single 16k x 8bit chip and simple desolder all 8 and fit a single chip to take care of all 16k ?
No, because the only chips that came in this configuration were SRAM chips, and while it is possible to get a SRAM chip to work, you need a number of other logic chips to interface it to the VDP. So while it is something that can be done without too many problems for new PCB designs, it's not so easy for existing computer designs.
Crazyboss wrote:At the Colelcovision they use the same setup, cause its the same VDP.

People like to change the 4116 to the 5v version, they said they drain less power and let the psu go cooler.

It should be possible to fit them too i guess I think its 4516 or something.
Yes, there are 5V single supply versions of 16k X 1 bit DRAM chips (HM4816, MCM4517, there maybe others). There are also 64 X 1 bit DRAM chips (various part numbers, but check the data sheet as some are 128 cycle refresh and some are 256 cycle refresh), both I believe can be used (I have not tried either for VDP RAM yet).

Mark

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Re: Another 4000-06 board

Post by Crazyboss » 26 Jul 2015 20:46

Another MTX512 is **NOW** fixed :)

I changed the ramchip at F6 as Martin suggested :) and soldered in a socket, I did not have the right socket so, I had to cut it a bit :)

After all this MTX has the best picture at my lcd monitor :) Already plugged in the Rememorizer and tested with Superpacman :)

Thanks guys.

I did wish Memotech had socketed the VRAM and RAM ic's as they are common to fail.
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//CLAUS - Webmaster at www.mtxworld.dk

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1024MAK
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Re: Another 4000-06 board

Post by 1024MAK » 26 Jul 2015 21:54

Well done 8-) :D

Although you did have me confused with your opening statement:
Crazyboss wrote:Another MTX512 is not fixed :)
:shock: :? :lol:
I think you should edit it and remove the "not" word and replace with the "now" word ;) :mrgreen:

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Re: Another 4000-06 board

Post by wyerd » 26 Jul 2015 23:29

1024MAK wrote:Well done 8-) :D

Although you did have me confused with your opening statement:
Crazyboss wrote:Another MTX512 is not fixed :)
:shock: :? :lol:
I think you should edit it and remove the "not" word and replace with the "now" word ;) :mrgreen:

Mark
Yeah! Confused me for a while :lol:

I like the way you hacked the socket to fit. Great stuff!

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Crazyboss
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Re: Another 4000-06 board

Post by Crazyboss » 27 Jul 2015 13:22

I really dont know what you are talking about :lol: I said "NOW" fixed marked in red... :mrgreen: :mrgreen: :mrgreen:
//CLAUS - Webmaster at www.mtxworld.dk

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