GBA1000 rev4 Build Log

If i understand well, the resistor R135 is a 33R2.
There are 2 ways to operate with a rev.4 board.

1) With osc. 50Mhz and R122 and without R135 and IC78

2) With osc. 100Mhz, R135 and IC78 and without R122

Someone that read well deutsch can pm me for a traslaction for this info?
Just for confirm that i understood well.

Thanks
 
Can you please repost the german here? I am sure plenty of people can translate or read german.
 
This is a copy of a questio/reply on a1k.org forum.

Question:

leider passt die liste nicht ganz. das meisste steht aber im eagle schaltplan.
@georg: welchen wert hatt denn bitte der R135?
das ist der einzigste den ich nicht herausfinden konnte.

gb97816 (georg braun) reply:

Ganz einfach: Auf dem Board kann statt eines 50MHz Oszillator ein 100 Mhz Oszi bestückt werden. Vorteil ist hierbei ein exaktes Tastverhältnis von 50 zu 50. Bei einem 50MHz Oszi kann das Verhältnis auch mal 40:60 sein. Die Schaltung mag das aber nicht sehr gerne...........

100MHz Oszi:
IC78 und R135 (33R2 wie R122) bestücken, R122 bleibt unbestückt.

50MHz Oszi:
IC78 kann, muss aber nicht bestückt sein. R122 bestückt, R135 unbestückt.
 
kipper2k said:
i'll probably start canvassing people for Gals after next weekend (not this weekend) once i recheck availability and prices.
Click to expand...

Dear Kipper2k,

Any luck with the GALs?

---------- Post added at 13:17 ---------- Previous post was at 12:55 ----------

One question regarding the component list....I'm not an expert electronic guy, so it might sound stupid :whistle:....at what voltage should the capacitors be rated? When shoping around I find everything from 25V, 50V and 100V....what would eb the best solution for this board?
 
My opinion.
This board are powered with 5v and 12v, capacitors 16v or 25v are good for use in all section.
Some section are powered by 5v and in this you can use capacitors 6.3v or 10v but (for me) i would prefer use 16v or 25v in all the board.
 
Almost done with my board:
sockets_4.jpg

Just need to do:
4 24pin IC sockets I forgot to order
4 20pin IC sockets I forgot to order
1 470R resistor pack I forgot to order
Placing the last of the custom IC's
Placing of the I1024 IC (ordered)
Placing of all GAL IC's (ordered)
Place Power Connector (ordered)
Place serial port (need to desolder from dead A600, the new one I ordered sticks out aprox 1mm)
(Maybe) Place a battery, not sure yet
Jumper board correctly

Testing...
 
Does anyone to make several ATX adaptator for the GBA or A1000 or can we buy this adaptator somewhere ?

I think I have all of the list of component exept spécial RCA connector :(
 
My board at 90 ou 95% :

c31c0b2


I loose my RJ11 connector and forgot to buy 2 chips and 1 resistor...
I must buy RCA connector but I don't finf them...

10 hours of work for this. The most dificult is to find components en read info for jumper, PAL/NTSC...
 
Last edited:
Hi,

I've forgoten IC34, the 27C256. It's the boot rom ? Where i can dl the program ?

Have you a ref for the support of batterie ?

Thanks.
 
yamakakiche said:
Hi,

I've forgoten IC34, the 27C256. It's the boot rom ? Where i can dl the program ?
Click to expand...

I'm also looking for the 27C256 contents. From another forum I read that it's either Oktagon 6.10 OR 6.12 OR a hacked/combined version of these two. Then someone else implicated it's an Oktapussy ROM. Confused! :blink:

Two other questions:
- did anyone figure out the RN5 value? (or did I miss this)
- what types of CY7C1049 RAM are supported by the board? Mainly I'm interested in operating voltage (3.3V or 5V) and speed.

Thanks in advance to the helpful ones. :)
 
@Lemmingn0s

I have see some photo of some gba1000 boards working and none of this have RN5 mounted.
Don't put them.
 
So IC34 is just for an Oktagon card ? Or it's for the IDE controller and we must have it for the boot on a CF card ?
 
The ide internal of the GBA1000 is strongly based on the AT bus 2008 card controller by BSC, and use his rom (or oktapussy).

From the GBA1000 user guide:

The GB A1000 motherboard includes an AT bus 2008 IDE controller by BSC. It has no RAM options and it only
contains the IDE function of the original circuit. To enable the auto boot feature of the IDE controller, the related
AT6.10 driver is used. The driver is loaded into EPROM IC34 (type 27C256). An image of the driver, in hex-file format,
is available on the internet at http://amiga.resource.cx/exp/atbus2008. Optionally the OKTAPUS device found on Aminet
can be used. This improves the functionality of the IDE controller.
Note: This is based on the original circuit from BSC. Due to lack of knowledge of the device, existing
deficiencies cannot be corrected. If an unsolvable problem arises I recommend the use of an
external IDE controller as for instance the Phoenix-Buddha.
On the GB A1000 motherboard you find two connectors for use of 40 pin and 44 pin IDE equipment. It is possible to use
equipment in master–slave operation, but not all device combinations will work. The IDE controller can be switched off
by closing jumper S2.
 
Hiya! First of all big thanks to piacc64 and Massimo for the help. I wrote a longer post on this subject, but somehow it got moderated out, unsure what was up with that :unsure:
Anyway, looks like there are options for the GBA1000 IDE-controller ROM binary.
The 6.10 version as referenced to by Massimo, and 6.12 from piacc64's post.
Are both of these compatible with the 68030 50MHz version of GBA1000?
Of course I'd rather use the newer version (6.12), if it works :)

One more question about passive components: Could anybody please confirm which resistors listed in the BOM are indeed 1K and which are 10K? I read from another thread that there had been some confusion in the generated bom-files regarding this, and that there _might_ be some kind of mix up regarding the positions of 10K and 1Kohm resistors on the board.
It could be just extra confusion and nothing to worry about, but since there are people here who have built a working GBA1000 unit, please confirm which Rxx:s are 1Kohm and which are 10Kohm.
Megathanks in advance! :)
 
Thanks Massimo ! I've order a 27C256 with the programm of piacc64.

You find these informations on GB's site ?
 
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