Super turbo PCB layout

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Van sdsnatcher73

Prophet (2150)

afbeelding van sdsnatcher73

26-04-2021, 21:01

I think an advantage for the QFP over SOP is that (as far as I can determine) QFP model is still produced.

Van SkalTura

Champion (328)

afbeelding van SkalTura

27-04-2021, 09:26

Pentarou wrote:

many cheap EPROM programmers can do it, and this project isn't really for inexperienced people.

True...
Do you have the schematic (and software) for the GAL version ?

Van SkalTura

Champion (328)

afbeelding van SkalTura

27-04-2021, 13:10

Did a quick test with the QFP version and the pinout of a DIP40 socket.
It's going to be very very very tight...

If you look at the below image of the PCB design software, its already giving collision warnings (red circles).
Not sure how much extra room there is to play with with the QFP layout, but I know that the actual chip will have slightly shorter pins then the space on the PCB.
So maybe I will simply adjust the PCB space just a little.

Van SkalTura

Champion (328)

afbeelding van SkalTura

27-04-2021, 15:18

Nevermind,.. Fixed the QFP package a bit, and the QFP to DIP40 part is now finished.
All I need now is to add the rest of the components.

Van sdsnatcher73

Prophet (2150)

afbeelding van sdsnatcher73

27-04-2021, 18:45

Also the PCB could be a little wider than the pins for the DIP40, right? If needed of course…

Van Pentarou

Champion (389)

afbeelding van Pentarou

27-04-2021, 19:01

SkalTura wrote:

Do you have the schematic (and software) for the GAL version ?

This is taken from the CIEL turbo schematic, you can download the whole schematics from here. (Expert3b.rar).
The CPLD .jed can be downloaded from here.

About the PCB: Maybe you could have adapted the ones from this page.

Van Gregory

Master (177)

afbeelding van Gregory

27-04-2021, 21:20

I just think we are making it way to hard. A pcb on top of a Z80 is just fine.

Van SkalTura

Champion (328)

afbeelding van SkalTura

28-04-2021, 07:22

Gregory wrote:

I just think we are making it way to hard. A pcb on top of a Z80 is just fine.

Totally agree.
But if it can be done... Why not, right ?

Van SkalTura

Champion (328)

afbeelding van SkalTura

28-04-2021, 07:52

Pentarou wrote:

About the PCB: Maybe you could have adapted the ones from this page.

Already solved the problem by trimming a little of the QFP package traces.

By the way, the adapter PCB on that page has the Z80 pins for mounting only on the bottom, not though-hole. You can see that the QFP pins will otherwise short circuit with them. Using only pins on the bottom and not trough-hole could tare off one of the pins when you try to remove the PCB from the Z80 socket. Not a good way of designing a PCB...

Will still be a challange though, because of the many traces from the Z80 on one side, the GAL and other components will mostly be mounted to the bottom.

About the schematic:
Where does pin 3 of the GAL go to... because I have no idea what is meant with IOB6...

About the Gal:
Is the SOIC version of the GAL still available...?
Would prefer not to use the PLCC version because of it's height.
Or is the Microchip ATF16V8 the same, because that one is available both as SOIC and TSSOP version...

Van SkalTura

Champion (328)

afbeelding van SkalTura

28-04-2021, 07:43

sdsnatcher73 wrote:

Also the PCB could be a little wider than the pins for the DIP40, right? If needed of course…

Yes, the PCB can be wider, but that is not the issue...
The QFP needs to fit between the "legs" of the DIL40 package in order to fit in the MSX socket.
the white lines you see in that picture is not the PCB by the way, but the top silkscreen of the DIL40 socket...

No worries, problem is solved and the Turbo PCB including Z80 will be made soon ;-)

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