2MB Agnus on A1000 and A2000

[TommyE]

Hello

I wonder if you think it would be possible to hack a newer Agnus into the older A1000 and A2000.

Thoughts:
- Would it be possible without having a Gary?
- Can it be possible with some simpler glue-logic or would one need more advanced stuff like some PAL/GAL/ASIC stuff.

Just thinking loud, maybe stupid thoughts, but seeing it has been done with the rejuvenator it should be feasible...

Regards
Tommy

 

[FastRobPlus]

Removed due to too many phone induced text errors

 

[TjLaZer]

Not possible on the A1000, easily possible on 2000 with a MegaChip board

 

[ptyerman]

Some A2000's already have a 2mb Agnus fitted. Mine does, but it is a later version that was released as a A1500. That said, it still only has 1mb of chip RAM.

 

[BlindGerMan]

Which Agnus is fitted?

 

[ptyerman]

Not sure, I haven't looked, but I suspect it's the same one as fitted in the A3000 as it's compatible with the socket, whereas the later 8375 isn't and needs a mega-chip adaptor. The A2000 has to be half stripped down before you can see the chips, so I won't see until the next time I strip it down, which will probably be to fit a Vampire when released.

 

[TommyE]

Hello all
Thanks for the reply.

I already know the differences between the varius Agnus versions. Also that the A1000 and A2000A has the DIP version and that it cannot be replaced with a PLCC version.

I have latetly been looking at the schematics for the A1000 and the A500, and it gave me the idea; would it be possible to create a board that would allow the use of the newer PLCC versions in an old A1000?

I see from the old DIP pinouts that what is missing from it compared to a newer PLCC is the adresslines that connects the new PLCC directly to the adress bus, but the old one does not do this. Most of the other pins are the same, and that leads me to think that with some creative 'glue-logic' it could be possible to get a newer PLCC version hooked up...

Does anyone know a good document that describes the internal connections/bus on the A1000?

I remember the rejuvenatior for the A1000, it made it possible, but it also had alot of other features like kickrom/A2000 videoslot.
I just want to explore the possibility of a DIY agnus adapter for the A1000.

Regards
Tommy

 

[Bebbo]

Hello all
Thanks for the reply.

I already know the differences between the varius Agnus versions. Also that the A1000 and A2000A has the DIP version and that it cannot be replaced with a PLCC version.

I have latetly been looking at the schematics for the A1000 and the A500, and it gave me the idea; would it be possible to create a board that would allow the use of the newer PLCC versions in an old A1000?

I see from the old DIP pinouts that what is missing from it compared to a newer PLCC is the adresslines that connects the new PLCC directly to the adress bus, but the old one does not do this. Most of the other pins are the same, and that leads me to think that with some creative 'glue-logic' it could be possible to get a newer PLCC version hooked up...

Does anyone know a good document that describes the internal connections/bus on the A1000?

I remember the rejuvenatior for the A1000, it made it possible, but it also had alot of other features like kickrom/A2000 videoslot.
I just want to explore the possibility of a DIY agnus adapter for the A1000.

Regards
Tommy

Connect A1-A20, /LDS, /UDS, /AS, R/W with the board (piggy back connector)
Connect DRD0-DRD15, /RES, RGA1-RGA8, /LPEN, /HSY, /VSY, /CSY, DMAL, /INTRQ, CCK, CCKQ, /BLS with the old Agnus socket. (and maybe /BLIT fits /DBR)
Add own DRAM using DRA0-DRA9, /CASL, /CASU, /RAS0, /RAS1, /WE
Wire somehow 28M, 14M, 7M
Provide somehow /RAMEN and /REGEN

... I am not far with my thoughts, but I am also considering such an expansion board.

Bebbo

 

[TommyE]

Hello all
Thanks for the reply.

I already know the differences between the varius Agnus versions. Also that the A1000 and A2000A has the DIP version and that it cannot be replaced with a PLCC version.

I have latetly been looking at the schematics for the A1000 and the A500, and it gave me the idea; would it be possible to create a board that would allow the use of the newer PLCC versions in an old A1000?

I see from the old DIP pinouts that what is missing from it compared to a newer PLCC is the adresslines that connects the new PLCC directly to the adress bus, but the old one does not do this. Most of the other pins are the same, and that leads me to think that with some creative 'glue-logic' it could be possible to get a newer PLCC version hooked up...

Does anyone know a good document that describes the internal connections/bus on the A1000?

I remember the rejuvenatior for the A1000, it made it possible, but it also had alot of other features like kickrom/A2000 videoslot.
I just want to explore the possibility of a DIY agnus adapter for the A1000.

Regards
Tommy

Connect A1-A20, /LDS, /UDS, /AS, R/W with the board (piggy back connector)
Connect DRD0-DRD15, /RES, RGA1-RGA8, /LPEN, /HSY, /VSY, /CSY, DMAL, /INTRQ, CCK, CCKQ, /BLS with the old Agnus socket. (and maybe /BLIT fits /DBR)
Add own DRAM using DRA0-DRA9, /CASL, /CASU, /RAS0, /RAS1, /WE
Wire somehow 28M, 14M, 7M
Provide somehow /RAMEN and /REGEN

... I am not far with my thoughts, but I am also considering such an expansion board.

Bebbo

Hello Bebbo.

Thanks for the thoughts, they are very much the same as mine.
I've ordered a PLCC breakout board, and as soon as I'm home from my vacation in Spain I'll try to wire something up.
I will first of all just see if I can replace the Agnus and keep the original 512kb and go from there.

Regards
Tommy

 

[Bebbo]

I will have a look at the Agnus alone - just power + 28MHz clock to see what signals are output / input.

My current plan is to build a board, replacing the piggy back, to plug into the 48 pin Agnus socket + cables to connect to the piggy back signals I need.
I will disable a bunch of chips on the main board - guess I solder them out and add a socket, so I can undo all changes.

Bebbo

 

[Fook42]

Hi.. did you made any significant progress on this ???? i'm really interested in such a thing and can also support by testing or designing PCBs or whatever

 

[TommyE]

Hi.. did you made any significant progress on this ???? i'm really interested in such a thing and can also support by testing or designing PCBs or whatever

Hello
Well not really.

I did order some parts, soldered up an agnus 8375 socket. Also mapped out all signals and drew a cad drawing of the new 2MByte memory board attached to Agnus.

I really haven't had the time to do much more.

I will contiunue on this if time permits.

Regards
Tommy