464 to 6128 spec woes

shock__ · 19:59, 07 October 17

Hey there,
I recently got a broken 464 which I fixed (ROM + 373 + 244 broken, shortcircuit on tape PCB) and upgraded to 6128 specs by adding a GAL, second RAM bank and swapping ROMs.
So far it seems to work nicely, 'Digital Orgasm' detects a 6128 with 128k RAM, nilquader's RAM tester checks out without errors.
Sadly the demo pheelone by condense does not work correctly. The first part (where it loads) looses sync rythmically, resulting in a rolling image and when the actual demo should start the screen just freezes. The CPC currently has a CRTC type 2 (actually tried a MC6845 and a HD68B45SP), but I've already ordered a type 1. Gate array is an Amstrad 40007. GAL is a Lattice GAL16V8D-15 using the fixed jedec by gerald. Other than that the machine has a DDI-1 interface, with a 3" drive connected as A: and a 3.5" drive connected as B: - which seem to work quite well (not completely without woes since the B: drive occasionally would have troubles detecting the put in disc and the LED being constantly on for some reason).

Any ideas what might cause the demo to crash? In WinAPE it works in a CRTC type 2 configuration. Other demos like DemoIzArt, Digital Orgasm, Midline Process or Phortem work nicely.

shock__ · 19:01, 08 October 17

Maybe anyone can check it on a 6128 with a CRTC type 2?
Either way I should have a CRTC type 0 and type 1 in the mail within the next few days - I hope that's the issue there.

gerald · 19:59, 09 October 17

Quote from: shock__ on 19:01, 08 October 17
Maybe anyone can check it on a 6128 with a CRTC type 2?
Either way I should have a CRTC type 0 and type 1 in the mail within the next few days - I hope that's the issue there.

Does not work on a CTRC2. Tested with the original AMSTRAD PAL and the fixed one.
Run fine with a CRTC0 or CRTC1 with both PAL

shock__ · 20:53, 09 October 17

Thanks for the heads up gerald

I should get a Hitachi CRTC 0 and an UMC CRTC 1 within the next few days and will report back.

shock__ · 12:51, 12 October 17

HD6845P is another incarnation of the CRTC 2? Oh man.
Now let's hope the UMC 6845R I ordered at least verifies as a CRTC 1

Bryce · 13:27, 12 October 17

The P version was never used in CPCs though.

Bryce.

shock__ · 18:17, 12 October 17

Seems like it ... just like the HD68B45SP I have.
To be perfectly honest it's getting kinda annoying to get a CRTC 0/1

I guess I might soon have enough spare chips to build my own KC Compact

shock__ · 11:48, 14 October 17

CRTC 1 has arrived and all is well.
Pheelone and Batman Forever now working flawlessly.

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464 to 6128 spec woes