Question about the gate array - new to Amstrad

[Fwapp]

Hi - I've just got my first Amstrad (CPC464) and am quite pleased with it.


As I always seem to do, I've whipped the cover off and had a look inside the case.


One thing I noticed is that in the IC space marked Amstrad 40007 (which is the gate array, similar to the ZX Spectrum ULA I understand) I have an 40008. Is this just a different version (again, like the ZX Spectrum's various ULA's?)

[Ast]

There is three différents types of Gate array. Only timing are différents I think... I've seen the difference in ACE Cpc Emulator by OffseT. Some minors différences.

[dragon]

The fifference in the gate arrays are the manufacturer (and tecnology type manufacture). 40007 is made with Ferranti's bipolar process 4008 with  LSI Logic's CMOS, and 40010 is manufacturer by italy's SGS Microelettronica but it use the same logic's cmos as lsi.

[ZbyniuR]

Amstrad part numbers - CPCWiki

Here nothing about timing.

[arnoldemu]

There is three différents types of Gate array. Only timing are différents I think... I've seen the difference in ACE Cpc Emulator by OffseT. Some minors différences.

There are differences in the pinouts (they can't be exchanged directly). There is a difference in the way mode 2 is displayed on 40007 and 40010. I don't know about 40008. On 40010 mode 2 pixels are delayed.

There may be a slight difference in the colours. I'm not sure of any other differences.

I have a feeling though that 40007 *may* also put values on the bus at interrupt time. But I need to confirm that.

[balford]

One thing I noticed there is that the photo above seems to contradict the wiki which states that the 40008 gate array has the same pinout as the 40010.

Fancy seeing you here, BTW

B

[Ast]

There are differences in the pinouts (they can't be exchanged directly). There is a difference in the way mode 2 is displayed on 40007 and 40010. I don't know about 40008. On 40010 mode 2 pixels are delayed.

There may be a slight difference in the colours. I'm not sure of any other differences.

I have a feeling though that 40007 *may* also put values on the bus at interrupt time. But I need to confirm that.

OffseT could explain the exact timing différences ;-)

[arnoldemu]

One thing I noticed there is that the photo above seems to contradict the wiki which states that the 40008 gate array has the same pinout as the 40010.

Corrected on the wiki

[Ast]

OffseT could explain the exact timing différences ;-)

Or maybe grimmy ?

[PulkoMandy]

The exact detail of the timing difference for mode 2 pixels is here:
documentations:devices:gatearray [Grimware]

Basically, the mode 2 pixels are shifted one pixel to the left on the 40010, but not on the 40007. The results on the 40008 are unknown, so it would be nice if you could test yours.

[TFM]

Awesome! You found the 1-pixel MODE 2 hardware scrolling! Now we just need a monkey exchanging the two GA versions quick enough in realtime!