A500 question

[apsturk]

Ok, I have an Amiga500 Rev6A. When I install an A501 mem upgrade it gets added to CHIP ram not fast. Is that normal or has someone done the mod so it will add it to chip ram. I also have an GVP 500HD+ with 8 meg's of fast ram. The workbench title shows a full 1meg Chip and a full 8meg of fast. Any thoughts
Thanks you

[apsturk]

Anyone? help

[smerf]

Hi,
Found this surfing the net for an answer, remember some sort of revisions, but this may explain it.

As mentioned in the post title, I have a 512k Rev 6a A500. The motherboard has additional socket spaces for another 512k of chip ram and the Agnus chip is rev 8372a #318069-02, which I believe supports up to 1mb chip ram?

To upgrade the memory to 1mb chip ram do I only have to populate the empty ram sockets and add in the necessary capacitors and Agnus will recognise the additional memory? Or will I have to also make changes to jumpers ie. JP2 or JP7?

I have 2 A501 512k trapdoor expansions so was thinking of using one as donor components as the chip versions match, then using the other as regular slow/fast ram in the trapdoor for a total of 1.5MB. Will that work?

I have also read an article on how to convert the A501 expansion into chip ram. Keen to know if anybody has done this hack and whether it's been successful and worthwhile.

So as you can see you may already have a hacked A500, if I get the fattest agnus chip for my A500, I may add chips to the empty sockets on the motherboard, then I have to cut some pad and wire going to the expansion port. If I had the time I would look it up in my Kazillion mods for Amiga computers. HMMM!!! it seems like I have a Karloss, anybody seen one.

smerf

[QuikSanz]

Ok, I have an Amiga500 Rev6A. When I install an A501 mem upgrade it gets added to CHIP ram not fast. Is that normal or has someone done the mod so it will add it to chip ram. I also have an GVP 500HD+ with 8 meg's of fast ram. The workbench title shows a full 1meg Chip and a full 8meg of fast. Any thoughts
Thanks you

Boy, it's been a long time since my A500, over 20 years. I seem to remember the dealer doing a mod. It consisted of a cut trace with a jumper wire. Some games would not work right and I had him return it to stock.

[Oldsmobile_Mike]

Most 6A boards default to 512k chip / 512k "slow fast". Obviously in the 20-something years since these boards have been produced any number of mods may have been done to them.

Take heart, it's much better to have 1MB chip / 8MB fast than it is to have 512K chip/512k "slow fast"/8MB fast.

[prowler]

Boy, it's been a long time since my A500, over 20 years. I seem to remember the dealer doing a mod. It consisted of a cut trace with a jumper wire. Some games would not work right and I had him return it to stock.

Yes, there was a basic mod you can do on the A500 if it was the right revision and if you had a the appropriate Agnus (1Mb) etc which would convert your 512Kb trapdoor RAM expansion to Chip RAM giving you 1Mb Chip. I helped a friend do it years ago after they bought an A590 and found they didn't have enough Chip RAM to do a number of tasks when using the hard drive.

[apsturk]

Most 6A boards default to 512k chip / 512k "slow fast". Obviously in the 20-something years since these boards have been produced any number of mods may have been done to them.

Take heart, it's much better to have 1MB chip / 8MB fast than it is to have 512K chip/512k "slow fast"/8MB fast.

Thanks Mike,
The reason I am asking is I have a DKB Megachip, so if the mod has been done I can just replace Angus with the Megachip to get 2 meg of chip ram with out having mod it myself. I will need to remove the a501 and all should be good if I understand it all correctly. any thoughts

-A

[jltursan]

You have a rev6A modded for sure, you can check the already mentioned jumpers JP2 and JP7A IIRC.

You can also use the megachip; but I'm not sure about the right way to upgrade the RAM past 2MB. You'll have a first 1MB chip thanks to the onboard 512KB + trapdoor A501 + mod, the second 1MB chip comes from the DKB. For more fast ram you'll need something like the Kipper's CPU RAM expansions (beware the sizes, 68000 and Agnus are close to each other!).

No bigger trapdoor RAM expansions seems to work with the DKB...

[zipper]

Thanks Mike,
The reason I am asking is I have a DKB Megachip, so if the mod has been done I can just replace Angus with the Megachip to get 2 meg of chip ram with out having mod it myself. I will need to remove the a501 and all should be good if I understand it all correctly. any thoughts

Exactly, that's (the mobo mod) what I've done  with my rev 6A to get 2 MB chip. The a501 is added to the chip memory, without it you do get just 1.5 chip.

[Oldsmobile_Mike]

Keep the A501.  Your motherboard provides 512k. A501 provides 512k. MegaChip adds the final 1MB.

[apsturk]

According the the DKB manual trapdoor ram (a501) CAN NOT be installed, if it is it will not work and may damage the computer

[zipper]

Yes - if " that takes more than 512k of RAM" (is the exact phrase in the manual)! Your board doesn't.

[apsturk]

Yes I just read that and logged on to post a correction. I guess ? that means I can just install the Megachip without any mods??  I think?

Thanks

[Oldsmobile_Mike]

Yes I just read that and logged on to post a correction. I guess ? that means I can just install the Megachip without any mods??  I think?

AAAAAHHHHHH.  Your system already has the mod.  You mean "no further mods".  

[apsturk]

Yes I believe so!! I am going to try it