English Amiga Board


Go Back   English Amiga Board > Support > support.Hardware

 
 
Thread Tools
Old 29 April 2010, 09:05   #1
Antti
A500 fan

Antti's Avatar
 
Join Date: Dec 2009
Location: Oulu / Finland
Posts: 68
How 2MB chip ram with the Mini Megi Chip?

I bought one of those NTSC Mini Megi Chips from Vesalia for my A500 (PAL). The installation guide was in german so it was quite difficult for me to understand it fully, but with a little help from Google translator I managed to get the chip installed. As it's stated in the guide, the trapdoor memory expansion needs to be turned off. I proved it to be true because my A500 didn't boot if it was turned on. Now I've got 1,5MB chip ram, so how can I get the full 2MB if I can't use the trapdoor expansion?

I have a rev6 mb and the memory expansion card is a 512kB Roctec RM550C.
Antti is offline  
Old 29 April 2010, 09:28   #2
Jope
-
Jope's Avatar
 
Join Date: Jul 2003
Location: Helsinki / Finland
Age: 39
Posts: 7,909
Did you have 1MB chip on the machine before? If you had 512/512, then you need to do the 1MB chip mod first.
Jope is offline  
Old 29 April 2010, 09:37   #3
alexh
Thalion Webshrine
alexh's Avatar
 
Join Date: Jan 2004
Location: Oxford
Posts: 12,393
Quote:
Originally Posted by Antti View Post
I bought one of those NTSC Mini Megi Chips from Vesalia for my A500 (PAL).
Did you fit a PAL 8375 2Mbyte Agnus to the Mini Megi? Or are you just using the NTSC one?

Quote:
Originally Posted by Antti View Post
I've got 1,5MB chip ram, so how can I get the full 2MB if I can't use the trapdoor expansion?
If you only have 512Kbytes Chip RAM on your motherboard I am pretty sure you've got to modify your motherboard in order for your 512Kbyte trapdoor RAM card to function or add more RAM to the motherboard. You need to read up.

http://aminet.net/search?query=agnus

Quote:
9b. FOR A REVISION 6 AND ABOVE AMIGA 500 WITH 512K CHIP RAM:

[ ] 9.13 Locate JP2 on the left side of the 40 pin ROM socket. Using
a sharp X-Acto Knife or similar item cut the trace connecting the
bottom and center pads. Then solder the top and center pads together.
Doing this will enable the A19 line from the 68000 to the Agnus
socket. Go on to the next step.

[ ] 9.14 Locate jumper JP7A to the left of the CNX expansion bus
connector. Using a sharp X-Acto Knife or similar item cut the trace
connecting the bottom and center pads. Once this trace is cut you do
not have to do anything else to this jumper. Make sure you do not cut
any other traces on the motherboard. Go on to the next step.

[ ] 9.15 If you do not have a 512K RAM board plugged into the CNX
expansion bus (the belly slot under the 500) you must do this now. At
this point your machine is compatible with the 1 meg Agnus and 2 meg
Agnus board.
alexh is offline  
Old 29 April 2010, 09:58   #4
Antti
A500 fan

Antti's Avatar
 
Join Date: Dec 2009
Location: Oulu / Finland
Posts: 68
@alexh: I'm using the NTSC one. Yeah, it's a bit frustrating to go to early startup menu on each cold boot...

@Jope & alexh: I already had modified the mb for 1MB chip, but I'm pretty sure I couldn't get the A500 to boot if the mod was enabled. By not booting I mean the screen remained black when I turned the power on. But I'll give it an another try when I get back home. I've soldered jumpers on the mb so it's quite easy to test again
Antti is offline  
Old 29 April 2010, 10:08   #5
alexh
Thalion Webshrine
alexh's Avatar
 
Join Date: Jan 2004
Location: Oxford
Posts: 12,393
If it doesn't work. Double check that your mod is correct.
alexh is offline  
Old 29 April 2010, 18:30   #6
Antti
A500 fan

Antti's Avatar
 
Join Date: Dec 2009
Location: Oulu / Finland
Posts: 68
Well, what do you know: It does boot after all! I must have had a loose connection somewhere yesterday Thanks for the help
Antti is offline  
Old 04 June 2014, 20:54   #7
Amiga_CDTV
Mind Walker
Amiga_CDTV's Avatar
 
Join Date: Oct 2013
Location: Helsinki, Finland
Posts: 152
Old thread but still: thumbs up

I bought a Mini Megi board and I just finished modding the board as instructed here: now I have 2 MB Chip Ram, and a working RTC (as I replaced the battery inside the A501) in my A500. Nice!
Amiga_CDTV is offline  
 


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Similar Threads
Thread Thread Starter Forum Replies Last Post
Games that needs 2MB Chip RAM (and no FastRAM) Dokugogagoji support.Games 13 28 September 2017 22:57
Breaking the 2MB Chip RAM limit nickynoo support.Hardware 30 16 May 2014 19:33
Mini Megi chip kipper2k support.Hardware 11 09 October 2009 15:26
Mini Megi Chip Memory Expansion A500/A2000 amigakit.com MarketPlace 0 01 August 2009 01:01
Super Agnus - 2MB Chip Ram THX1138 support.Hardware 8 06 July 2008 12:29

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +2. The time now is 12:20.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
Page generated in 0.06990 seconds with 13 queries