Changing CRTC

protek · 21:04, 07 January 13

Yup, I've ordered some memory before for my RTG card and those worked.

Bryce · 21:08, 07 January 13

I'd certainly order there again and probably will in the near future. I've just checked my orders and I've tonnes of stuff from them:

AD724
µP765
SED9420
FDC9266
27C160
27V160
WDC1770
WDC1772

And a few hundred 74LSxx ICs as well. Not a single fake among them. If you are ordering big numbers of parts I'd recommend doing it from their site and getting a quote, rather than ordering through ebay.

Bryce.

TFM · 21:15, 07 January 13

Just out of curiosity: Would it be possible to solder different CRTCs over each other and only activate the Chip-select signal of one of them. So a switch could select one of them. Or do I miss something?

Bryce · 21:28, 07 January 13

No. As mentioned earlier (can't remember who, it wasn't me

), the CRTC is always outputting a signal and reading RAM, the CE is actually a CS, so it only enables / disables the address input lines, not the entire IC.

Bryce.

protek · 21:32, 07 January 13

Bryce, do you remember what kind of delivery times Utsource has had? Mine was shipped yesterday from Hong Kong. I did the transaction already before Christmas, though.

Bryce · 21:40, 07 January 13

Around Christmas is never going to be a good time. I think most of my stuff arrived between 15 to 30 days from the order date.

Bryce.

TFM · 21:46, 07 January 13

Quote from: Bryce on 21:28, 07 January 13
No. As mentioned earlier (can't remember who, it wasn't me ), the CRTC is always outputting a signal and reading RAM, the CE is actually a CS, so it only enables / disables the address input lines, not the entire IC.

Bryce.

May be there any other pin usable? Vpp?

Bryce · 21:55, 07 January 13

Maybe, you'd need to test it. You also couldn't put many in parallel, the analogue outputs will all have resistors to ground, so each extra CRTC effects the image a little, even if it's not powered.

Bryce.

TFM · 21:58, 07 January 13

Ok, so back to the text tool socket.

Bryce · 22:02, 07 January 13

Would a ZIF Socket fit in there? They are pretty high, would it not hit the keyboard?

Bryce.

TFM · 22:05, 07 January 13

Good question, rather not. But I haven't been completely serious.

The best way is probably to just switch the keyboard instead of the CRTC. Ok, so you need at least three CPC6128 keyboards.

db6128 · 23:47, 07 January 13

I'll stick with a normal socket and just use a screwdriver if I need to.

TFM · 03:03, 08 January 13

That could be more often the case when watching demos...

protek · 07:55, 15 January 13

Just received notification that the new CRTC had arrived in Oulu. Stay tuned....

protek · 22:07, 15 January 13

Received the new CRTC chip today from UtSoucre. It is a HD6845SP, which is type 0, if I remember correctly.

Since I had the socket already in place, it was a simply a matter of plugging the new chip in and we were set.

Phew! Safely in Locomotive Basic!

Now the moment of truth. Are we able to run the Batman Forever demo, which wouldn't run on the original type 2 CRTC?

So far so good...

And here we go!

Was it worth the trouble? Definitely. I've been hoping to see Batman Forever demo on real hw for some time.

If someone has the type 2 by Motorola in their Amstrad and wishes to upgrade, UtSource has the type 0 by Hitachi for sale at eBay.

db6128 · 22:41, 15 January 13

Good to know that the SP works just as well as the S, which is the one quoted in all the tables online.

I bought a type 1 (UM6845R) and have a type 0 (UM6845) in my ailing 464, so I will replace the type 2 in my 6128 eventually. But the socket I ordered hasn't arrived. :|

TFM · 21:57, 16 January 13

Patience is a virtue

Code a 16 KB ROM game meanwhile

Syncmaster319 · 00:03, 09 March 19

Hi all,

Sorry to resurrect this old thread but search brought me here and wondered if the advice was any different.

I have a newly acquired near mint 6128 which was an eBay impulse purchase. No regrets!

Unfortunately it has a CRTC 2 so a lot of the good demos don't run. Is it still the case I can swap the CRTC out?

If so which CRTC would you recommend and where can I purchase both a socket and a compatible chip?

Thanks in advance!
Mark

TotO · 00:30, 09 March 19

May be someone programming demo will enjoy to exchange a mainboard for your CRTC2 version instead?
Else, I should provide you a socket and a CRTC 1 if you want the good one to run most demos.

Quote from: Syncmaster319 on 00:03, 09 March 19
Hi all,

Sorry to resurrect this old thread but search brought me here and wondered if the advice was any different.

I have a newly acquired near mint 6128 which was an eBay impulse purchase. No regrets!

Unfortunately it has a CRTC 2 so a lot of the good demos don't run. Is it still the case I can swap the CRTC out?

If so which CRTC would you recommend and where can I purchase both a socket and a compatible chip?

Thanks in advance!
Mark

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Changing CRTC