English Amiga Board Amiga Lore


Go Back   English Amiga Board > Support > support.Hardware > Hardware mods

 
 
Thread Tools
Old 06 February 2008, 10:32   #21
DrF
Blessed A1200 Of TeH Rat
DrF's Avatar
 
Join Date: Aug 2007
Location: Bham, UK
Age: 32
Posts: 497
So has anyone worked out what happens to the trapdoor expanstion slot after this mod?

I would assume that either by putting a A601 or silmiler in there, the A600 would either not see it and carry on, or not work?

Now if there was a way of getting more fast ram without paying a sh*t load of cash
DrF is offline  
AdSense AdSense  




Old 06 February 2008, 11:28   #22
alexh
Thalion Webshrine
alexh's Avatar
 
Join Date: Jan 2004
Location: Oxford
Posts: 11,173
I personally think you might get a fire.

Two chips driving the same wire? No thank you.

For A600 FastRAM you just buy one from LordV and assemble it yourself.
alexh is offline  
Old 06 February 2008, 11:29   #23
Jope
-
Jope's Avatar
 
Join Date: Jul 2003
Location: Helsinki / Finland
Age: 34
Posts: 4,461
Send a message via MSN to Jope Send a message via Skype™ to Jope
It will conflict.. Most probably the machine will just crash when you access the second megabyte of chip RAM.
Jope is offline  
Old 06 February 2008, 13:24   #24
Merlin
AmiBay MegaMod
Merlin's Avatar
 
Join Date: Mar 2007
Location: Manchester, UK
Age: 52
Posts: 1,153
@ alexh

I would have thought you were more at risk of a fire from sticking an Apollo into your A600.

Just how much current at 3.3v are you expecting to draw down the wires feeding two ram chips, in order to cause a fire? If your argument held any water, adding extra ram chips to the main board of an A500 should also cause the same effect, would it not?

M
Merlin is offline  
Old 06 February 2008, 13:27   #25
Merlin
AmiBay MegaMod
Merlin's Avatar
 
Join Date: Mar 2007
Location: Manchester, UK
Age: 52
Posts: 1,153
@ DrF

The trapdoor is basically redundant after this mod, as the 8375 Agnus can only address 2Mb of chip ram. More than 2Mb of chip ram on the A600 requires a DRAM controller as per Lord Vader's mod, in order to address the memory above the standard 2Mb.

That is why Lord Vader needs the CPLD device.

M
Merlin is offline  
Old 06 February 2008, 13:30   #26
Jope
-
Jope's Avatar
 
Join Date: Jul 2003
Location: Helsinki / Finland
Age: 34
Posts: 4,461
Send a message via MSN to Jope Send a message via Skype™ to Jope
More than 2MB of chip RAM requires a redesign of the Agnus.
Jope is offline  
Old 06 February 2008, 13:32   #27
Merlin
AmiBay MegaMod
Merlin's Avatar
 
Join Date: Mar 2007
Location: Manchester, UK
Age: 52
Posts: 1,153
^^^ What Jope said as well ^^^

M
Merlin is offline  
Old 06 February 2008, 13:52   #28
alexh
Thalion Webshrine
alexh's Avatar
 
Join Date: Jan 2004
Location: Oxford
Posts: 11,173
Quote:
Originally Posted by Merlin View Post
Just how much current at 3.3v are you expecting to draw down the wires feeding two ram chips, in order to cause a fire? If your argument held any water, adding extra ram chips to the main board of an A500 should also cause the same effect, would it not?
No. How can I explain it in a "Dummies guide to hardware" style?

When you add extra RAM to an Amiga, normally you add the RAM to unique addresses. No RAM occupies the same address as other RAM.

If you solder in RAM to your A600 in the 2Mbyte chip RANGE ($080000-$1FFFFF) and then also add an A601 (trapdoor) expansion (also at $080000-$1FFFFF) you are adding them in parallel.

A read comes in and BOTH chips try to drive the data bus (wires) at the same time!
alexh is offline  
Old 06 February 2008, 13:56   #29
Merlin
AmiBay MegaMod
Merlin's Avatar
 
Join Date: Mar 2007
Location: Manchester, UK
Age: 52
Posts: 1,153
Fair enough-ski, I read your post in the electrical sense, not the data sense.

Anyone who tries this mod is taking a risk anyway.

M
Merlin is offline  
Old 06 February 2008, 13:57   #30
Jope
-
Jope's Avatar
 
Join Date: Jul 2003
Location: Helsinki / Finland
Age: 34
Posts: 4,461
Send a message via MSN to Jope Send a message via Skype™ to Jope
That might lead to fried drivers in the chips, but are you serious that there's enough current flowing there to burn traces off the board? It's just signals after all.
Jope is offline  
Old 06 February 2008, 14:00   #31
coze
hastala vista winny vista
coze's Avatar
 
Join Date: Feb 2006
Location: mt fuji
Age: 36
Posts: 1,333
Send a message via ICQ to coze Send a message via Yahoo to coze
Quote:
Originally Posted by Jope View Post
More than 2MB of chip RAM requires a redesign of the Agnus.
also, the denise, paula (basicly all chips which will acess it), and a redesign of the memory map, whole adress bus and probably changes to kickstart.

so actually it requires a new ECS design
coze is offline  
Old 06 February 2008, 14:14   #32
DrF
Blessed A1200 Of TeH Rat
DrF's Avatar
 
Join Date: Aug 2007
Location: Bham, UK
Age: 32
Posts: 497
I know theres a 2Mb chip ram limit, I was thinking like this VERY old A500 I have where if I added a 1Mb trapdoor expanstion (A501+ I think it was) it would give me 1Mb fast and leave the orig. chip ram alone, the same expanstion on a A500+ gave me 2Mb chip ram, I went on about it in another thread, not so long ago, why it did this no one could work out, but there ya go
DrF is offline  
Old 06 February 2008, 14:45   #33
Charlie
. . Mouse . .
Charlie's Avatar
 
Join Date: Jun 2005
Location: Nowhere
Age: 45
Posts: 1,792
Hacking - good.
Clockport - better?

Don't discount AK's upgrade. That little clockport header could make all the difference to a project...
...but what if you want to use the expansion port for something else..?
...back to hacking...
...but will the expansion port be useable for anything after this hack..?

...my brain hurts...
Charlie is offline  
Old 06 February 2008, 14:49   #34
alexh
Thalion Webshrine
alexh's Avatar
 
Join Date: Jan 2004
Location: Oxford
Posts: 11,173
Quote:
Originally Posted by DrF View Post
I added a 1Mb trapdoor expanstion (A501+ I think it was) it would give me 1Mb fast and leave the orig. chip ram alone, the same expanstion on a A500+ gave me 2Mb chip ram, I went on about it in another thread, not so long ago, why it did this no one could work out, but there ya go
The A500+ has an 8375 2Mbyte Agnus regular A500's have either an 8371 512Kbyte Agnus or an 8372 1Mbyte Agnus.

Adding an an A501+ to a regular A500 (if it works) would probably only give 512Kbyte Fast RAM.
alexh is offline  
Old 06 February 2008, 17:13   #35
rkauer
I hate potatos and shirts
rkauer's Avatar
 
Join Date: Oct 2007
Location: Sao Leopoldo / Brazil
Age: 48
Posts: 3,478
Send a message via MSN to rkauer Send a message via Yahoo to rkauer
If someone want to make his own "A601", without RTC, nor clockport, I've uploaded one to Aminet:
http://aminet.net/docs/hard/Tabajara.zip

It is in html form, so any computer can read it. The instructions are in english and brazilian portuguese.
rkauer is offline  
Old 06 February 2008, 17:13   #36
Merlin
AmiBay MegaMod
Merlin's Avatar
 
Join Date: Mar 2007
Location: Manchester, UK
Age: 52
Posts: 1,153
@ Charlie

In a word, NO. The expansion port can't be used for data after this hack as the Agnus is at it's 2Mb limit.

@ DrF

You haven't got an A501+ 1Mb upgrade going spare, have you? (Hint hint)

M
Merlin is offline  
Old 06 February 2008, 17:21   #37
Toni Wilen
WinUAE developer
 
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 39
Posts: 14,213
Quote:
Originally Posted by coze View Post
also, the denise, paula (basicly all chips which will acess it), and a redesign of the memory map, whole adress bus and probably changes to kickstart.

so actually it requires a new ECS design
Original Denise and Paula will be compatible. All DMA address pointers are in Agnus. (Agnus fetches the data using DMA and then writes it to Paula/Denise xxxDAT registers)
Toni Wilen is offline  
Old 06 February 2008, 17:26   #38
Merlin
AmiBay MegaMod
Merlin's Avatar
 
Join Date: Mar 2007
Location: Manchester, UK
Age: 52
Posts: 1,153
@ rkauer

I started to work out the pinouts for your project from the tables listed and I needed coffee and paracetamol after 10 minutes, to be honest it was easier for me to translate the German hack described above (lazy git that I am LOL).

Edit: Anyone for a schematic? Courtesy of Zetr0 and yours truly, credit to Ralf at a1.org for the hack.



M
Attached Thumbnails
Click image for larger version

Name:	a6002mbhh.jpg
Views:	461
Size:	171.3 KB
ID:	15861  

Last edited by Merlin; 06 February 2008 at 23:36.
Merlin is offline  
Old 07 February 2008, 17:59   #39
Merlin
AmiBay MegaMod
Merlin's Avatar
 
Join Date: Mar 2007
Location: Manchester, UK
Age: 52
Posts: 1,153
For those who may be interested, I nabbed two S3 Trio 2Mb graphics cards with compatible chips from Fleabay for £8 all in, that's enough chips to mod four A600s. Cirrus Logic cards seem to be going for similar prices.

Go get 'em lads!!

Merlin
Merlin is offline  
Old 16 June 2008, 21:52   #40
Hungry Horace
Wipe-Out Enthusiast

Hungry Horace's Avatar
 
Join Date: Nov 2005
Location: #pspuae chatroom
Age: 33
Posts: 2,407
i love the fact that in this thread from only a few months back "1mb chip ram expansions are dead cheap" and "you can easily get one from amigakit"

4 months and things have changed that much? all i see is "Out of Stock" on every a600 chip expansion on any amiga shop, and massively inflated e-bay prices.

if i have compatible chips, i've very tempted to try this.
Hungry Horace is offline  
AdSense AdSense  
 


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

Similar Threads
Thread Thread Starter Forum Replies Last Post
How 2MB chip ram with the Mini Megi Chip? Antti support.Hardware 6 04 June 2014 20:54
A600 w/ 1MB Chip + 4MB Fast Ram = WHDLoad success rate? Kenan support.Hardware 7 08 May 2013 18:14
A600 chip ram problem??????? wangerman69 support.Hardware 17 06 July 2012 23:33
[SAS/C] Making malloc() allocate in fast RAM instead of chip RAM? 8bitbubsy Coders. General 3 07 August 2011 07:06
not enough chip ram a500? skforty support.Hardware 33 07 August 2009 22:53

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 21:58.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Page generated in 0.20789 seconds with 12 queries