Circuits Available for Elektor 6502 CPU card and Samson?

[adsouza]

hello:

i currently own an Elektor Electronics Junior Computer. i am now interested in designing my own 6502 or 65C02 based computer. for this, i would like to review the circuit schematics of the Elektor 6502 CPU card that was published in Dec 1983, iirc.

for those who don't know, Elektor Electronics is an hobbyist electronics magazine that is still published today.

Elektor Electronics
http://www.elektor.com/

besides, i am also interested in the Elektor Samson computer, that was published by the German branch of Elektor Electronics. i think, iirc, that the Samson used a 65816.

[Ruud]

adsouza wrote:

..., i would like to review the circuit schematics of the Elektor 6502 CPU card that was published in Dec 1983, iirc.

http://www.baltissen.org/newhtm/elektuur.htm

Otherwise send me a PM.

[adsouza]

hello Ruud:

>> i would like to review the circuit schematics of the Elektor 6502
>> CPU card that was published in Dec 1983, iirc.
>
> http://www.baltissen.org/newhtm/elektuur.htm
>
> Otherwise send me a PM.

i checked on the above page and the Elektor 6502 CPU card
that was published in Dec 1983 is not there.

i also checked the schematic of the 'EC-65 computer' that is
given on this page and i have a question regarding it:
- the signal that is used to control G\ on IC13A, IC13B, IC12A,
and so on, is not generated anywhere in the schematic.

- the above signal is also used to enable data bus buffer
at G\ IC14 (pin 19 74LS245). the schematic does not show
where the signal is generated

my question is this:
where is the signal to G\ pin19 of IC14 generated in the
circuit for the Elektor EC-65 computer?

thank you in advance for your information.

[smilingphoenix]

If you follow the circuit, you will find that the G pins on ICs 12, 13, 14 are pulled up to VCC (+5V) by resistor R10. This simply holds all the G pins at a constant logic 1

I've just noticed - all these pins are active-low, so these chips will be constantly disabled. Damn - I should have looked more closely before posting this reply and feeling clever!

[Ruud]

adsouza wrote:

i checked on the above page and the Elektor 6502 CPU card that was published in Dec 1983 is not there.

Hmmm, it seems the PNG is missing indeed. I'll try to take care of it ASAP.

adsouza wrote:

i also checked the schematic of the 'EC-65 computer' that is
given on this page and i have a question regarding it:
- the signal that is used to control G\ on IC13A, IC13B, IC12A,
and so on, is not generated anywhere in the schematic.
- the above signal is also used to enable data bus buffer
at G\ IC14 (pin 19 74LS245). the schematic does not show
where the signal is generated

Mistake? Shall check it out.

[Ruud]

Ruud wrote:

Hmmm, it seems the PNG is missing indeed. I'll try to take care of it ASAP.
+
Mistake? Shall check it out.

The PNG is now available.
What was missing is a simple jumper to GND. The explanation: A jumper must be placed to make things work. For future use the jumper can be removed and the ICs can be operated by other hardware.

[adsouza]

thank you fellows for your help with this. i sincerely appreciate it.

> The PNG is now available.
> What was missing is a simple jumper to GND. The explanation: A jumper
> must be placed to make things work. For future use the jumper can be
> removed and the ICs can be operated by other hardware.

i checked the PNG for EC-65 computer Schematics 6502 card and the
jumper you mention is not yet present. i mean the line connecting
IC14/G/p19, IC10,11,12,13/G/p1,p19

is there a jumper that connects this line to ground?

[Ruud]

adsouza wrote:

thank you fellows for your help with this. i sincerely appreciate it.

> The PNG is now available.
> What was missing is a simple jumper to GND. The explanation: A jumper
> must be placed to make things work. For future use the jumper can be
> removed and the ICs can be operated by other hardware.

i checked the PNG for EC-65 computer Schematics 6502 card and the
jumper you mention is not yet present. i mean the line connecting
IC14/G/p19, IC10,11,12,13/G/p1,p19

is there a jumper that connects this line to ground?

You have to add the jumper yourself to the schematics for the moment.

[adsouza]

> You have to add the jumper yourself to the schematics for the moment.

okay. thank you for clearing up the confusion.

take care,

Aaron
--
{ go NorCal, go SoCal, go California! }