Amiga 500 and 1 MB on chip RAM

[cosmicfrog]

also if you add the chips to your motherboard your 512meg trapdoor expansion would become usless

I`m with alex on this one, you probably got a software conflict somewhere
is Amiga Explorer the only thing that crashes

[Fabie]

if amiga explorer crash....ot there are problems ...

you can try another serial device like the baudbandit.device
maybe the normal serial .device needs fast memory or something like that
that hacked serial device I know that works on the A500 and maybe it will not crash using the new 1 mb chip ram config

also you can try 8n1.device...but I don't know if it will work there

on my A1200 020 +8mb fast ram on amiga explorer I use 8n1.device and I get 115.200 speed....with the normal serial device (WB 3.1) I can get only 57600

bye

[Lockon]

Is it possible to populate those empty DIL sockets with DRAM on Rev6, add to ChipRAM pool and still use trapdoor RAM expansion as SlowRAM ?
That would yield as 1Mb CHIP and 512Kb PseudoFAST.

[Chain]

Originally Posted by Lockon

Is it possible to populate those empty DIL sockets with DRAM on Rev6, add to ChipRAM pool and still use trapdoor RAM expansion as SlowRAM ?
That would yield as 1Mb CHIP and 512Kb PseudoFAST.

NO, is not that easy

[Lockon]

OK, fair enough.


Can you shed some light on that matter ?
Bank switching logic ?

[Jope]

You need separate ras/cas signals to them. It is doable, there was a thread about it here.

Chain, do you have your final schematics available somewhere?

[Lockon]

Oh, I see. Thnx for clarification.
It' not worth of a hassle, I'm better with a A500+ mobo.

[caiusfabricius]

Originally Posted by Fabie

if amiga explorer crash....ot there are problems ...

you can try another serial device like the baudbandit.device
maybe the normal serial .device needs fast memory or something like that
that hacked serial device I know that works on the A500 and maybe it will not crash using the new 1 mb chip ram config

also you can try 8n1.device...but I don't know if it will work there

on my A1200 020 +8mb fast ram on amiga explorer I use 8n1.device and I get 115.200 speed....with the normal serial device (WB 3.1) I can get only 57600

bye

The problem is that Amiga crashes only when I use Amiga Explorer with the hardware hack, it works normally without the mod, so I presume it's a fault of this hack..I repeat, I have an Amiga 500 ( 6A revision motherboard) with 512 kB expansion, a kickstart switcher (1.3/3.1), a 68010 CPU and a AlfaData hard disk with 4 MB of ZIP RAM so I have enough FAST RAM..

[alexh]

Originally Posted by caiusfabricius

The problem is that Amiga crashes only when I use Amiga Explorer with the hardware hack, it works normally without the mod, so I presume it's a fault of this hack..

Very poor deductive reasoning.

It is just as likely to be due to a software conflict with 1Mbyte Chip RAM.

Or a conflict from using a 68010 (very unusual Amiga CPU) triggered only when you have 1Mbyte Chip RAM.

Try downgrading back to 68000.

Try to use a memory test program to see if the 1Mbyte chip RAM is working correctly between CPU & RAM

Try to use a few 1Mbyte Chip programs and confirm the 1Mbyte Chip RAM is working correctly between custom chips & RAM.

[caiusfabricius]

Originally Posted by alexh

Very poor deductive reasoning.

It is just as likely to be due to a software conflict with 1Mbyte Chip RAM.

Or a conflict from using a 68010 (very unusual Amiga CPU) triggered only when you have 1Mbyte Chip RAM.

Try downgrading back to 68000.

Try to use a memory test program to see if the 1Mbyte chip RAM is working correctly between CPU & RAM

Try to use a few 1Mbyte Chip programs and confirm the 1Mbyte Chip RAM is working correctly between custom chips & RAM.

Ok, thanks for the advices.I put a 68010 CPU to benefit of the quit key in WHDLoad.When I use the hardware hack except for Amiga Explorer all was fine, I played Xenon II which requires 1 Mbyte of chip RAM to run with WHDLoad. Which programs can I use to test chip RAM communications?

[Fabie]

Alex is right

test first if the 1mb hack is working ok...otherwise leave the computer original

try a memory test program like memcheck

http://aminet.net/util/moni/MemCheck12.lha

also try the 8n1.device on amiga explorer..maybe will work

http://aminet.net/comm/misc/8n1.lha

also test and run from floppy the games Dracula & Turbotrax (not AGA games but requires 1mb chip)

[Jope]

Look at the avail command's output (start a shell first) and see if you really have only 1MB chip and no fast when you have the machine configured for 1MB chip.

[caiusfabricius]

Originally Posted by Jope

Look at the avail command's output (start a shell first) and see if you really have only 1MB chip and no fast when you have the machine configured for 1MB chip.

Now I'm without the hack but if I remember well when I used the hack I had 1 Mbyte of chip RAM and 4,5 Mbytes of fast RAM (512kB of the expansion + 4 Mbytes of the hard disk controller)..it does matter?When the machine is configured with 1 Mbyte of chip PAM it has to be without any other type of RAM?

[Jope]

You should only have had 1MB chip and 4MB fast in that case, the trapdoor RAM expansion becomes chip ram.

Did you make sure you cut JP7 properly?

[caiusfabricius]

Originally Posted by Jope

You should only have had 1MB chip and 4MB fast in that case, the trapdoor RAM expansion becomes chip ram.

Did you make sure you cut JP7 properly?

Yes, pardon..I meant 4 Mbytes of fast RAM not 4.5 as said before.Yes, I cut the JP7A properly and checked it with multimeter.

[DyLucke]

Hello, i wouldn't like to interfere here but i have some doubts about this, and as long as you're treating the matter here i feel like i could ask.

Erm i do have one of these A500 rev6 miggies, and i have it installed with the stock 512k chipram plus a trapdoor expansion that has 2mb (it has a cable and a substitution gary)

Question is, actually i do have 2,5mb in total, but i can only see 2mb in workbench.
Is there any way i could have more than 2mb using the trapdoor?
What would happen if i add more ram on the empty slots for chipram on the motherboard?

And a last one? A500 plus has the same behaviour? Or could it address more than 2mb thru the trapdoor?

Thanks a lot!

[alexh]

A500 plus is completely different. It has an 8375 Agnus and 2Mbytes of chip RAM (1 of which is via trap door).

Unknown what it's behaviour is with RAM card with more than 1Mbyte + Gary adapter.

[Chain]

Originally Posted by Jope

You need separate ras/cas signals to them. It is doable, there was a thread about it here.

Chain, do you have your final schematics available somewhere?

im not sure if they are final, as that machine is unstable and unusable now .
I still dont had a time to make it on small pcb (damn interferences).
Maybe on xmas holidays

[rkauer]

I'm thinking in other newer hardware to expand the A500, but I'll show it only after testing my theory in a salvaged A500.

I will start with 128kb and add more static RAM to it if it works. Those chips can be salvaged from old pc boards 61C256A-20 and 61C256A-12. Those are 20 and 12ns access time, 32kb x 8bit per chip.

No need for clock, no need for RAS/CAS. Just addressing and the chip enabling line. Of course, larger static RAM chips can be expensive, but removing the hassle for RAS/CAS headache can be valid.

Sorry for posting to an old thread, but there's also a solution to 1 Mb chip RAM upgrade that doesn't require modifying the motherboard at all. This does require electronics skills, but at least you don't risk ruining your Amiga. This works also on old rev 3 motherboards, no need to cut traces and solder jumper wires on the PCB. It's also easy to change between slow mem and chip mem with two jumpers.

Check out https://inkoovintagecomputing.wordpr...modifications/