A500 - 6A, 1MB chip + some fast - Page 2

Chain · 31 August 2007, 13:45

im pretty sure your board does not have this logic.
without that you will be stuck with 1mb chip/512+512, nothing more

Jope · 31 August 2007, 14:38

Zetro, you're talking about a different thing than Chain..

How I understood this:

Zetro: solder RAM chips to motherboard for 1MB CHIP

Chain's question + the schematic Wilen dug up: solder RAM chips to motherboard for 1MB CHIP and do a modification (per the schematic) to be able to have 512kB slow FAST in the trapdoor + 1MB CHIP on the mobo for a total of 1.5MB of internal memory.

Zetr0 · 31 August 2007, 17:14

AHhhhhhhhhhhhhhhhhhh

indeedy i was getting confused!!!!!

sorry about that guys...

thanks jope

Zetr0 · 25 September 2007, 13:56

@Chain

How are you getting on with this?

DrF · 25 September 2007, 14:21

I am sure I seen a even more weird hack years ago, where they ended up stacking the RAM chips on top of each other and then there was a crap load of wire everywhere, needless to say I never tried it...

Chain · 25 September 2007, 14:57

i dont want it piggybackin connected, as you cant fit keyboard back

im still searching for 74f02 part in smd (i know i can substitute it but it will be one more chip)

CRAZG · 06 October 2007, 09:28

I am trying this on my 6a boards (2) but so far have only soldered the new ram in place. I am a little confused about the effect of these jumpers etc. As I understand there are two scenarios here; one where you add 512k chip and this disables the expansion? and one where you add 512k ?fast? and leave the expansion slot enabled?
I would like to leave the expansion enabled and have 1500k if possible.

Chain · 15 October 2007, 19:17

hellyeah it works that way - 1 meg chip +0.5 meg fast

but its unstable, dunno if its long wires or that damn solderless board

always hangs or crashes (dark green screen, white dropouts, out of sync) after few seconds

DrF · 15 October 2007, 19:21

Quote:

Originally Posted by Chain

always hangs or crashes (dark green screen, white dropouts, out of sync) after few seconds

I have faith in you!

Use the force or something, at least the A500 is coming on, are you sure some of the RAM chips have not gone bad?

Don't give up

Chain · 15 October 2007, 19:45

i wil try to replace 74LowStability08 with 74Faith08, but tomorrow

Jope · 15 October 2007, 21:42

Yeah, keep the wire lengths to a minimum and don't use breadboard, solder some sockets to a vero board instead and plug the logic glue into those.. :-)

Zetr0 · 15 October 2007, 22:00

so how does one get 2MB chip ram on an R6A A500 ?

anyone got any techs?

Chain · 15 October 2007, 22:22

i only know something about replacing 256x4 chips with 1mx4 chips, replacing agnus and A LOT of rewiring

thats all. no schematic, not even a clue

Doc Mindie · 15 October 2007, 23:09

Quote:

Originally Posted by Zetr0

so how does one get 2MB chip ram on an R6A A500 ?

anyone got any techs?

For that I believe you need the obese Agnus, not just the fat one? + some extra hardware of some sort.... I know there's a something likeMegaChip that used to be sold, some hardware and Agnus replacement that allowed you 2MB chip on a (otherwise) bog standard A500

Eclipse · 16 October 2007, 00:38

Don't know if this helps.
http://webcebi.com/Amiga/

Jope · 16 October 2007, 08:05

That is not it. You need to do a lot more more cutting and rewiring to fit the 2MB Agnus on the A500 motherboard..

It is doable, I have seen instructions, but I have no idea where it was.. Perhaps in some magazine.

Charlie · 16 October 2007, 20:26

Quote:

Commodore is now shipping the Obese Agnus in most of the current A500s
(without telling anybody) although Commodore in the USA will admit to
it when questioned. These A500s are set up in Fat Agnus Mode so that
even if an A501 board is plugged into them no improvement is obtained
without further internal modification.

I don't know if the article is of any interest here.
http://www.skepticfiles.org/cowtext/comput~1/buildit.htm

Jope · 17 October 2007, 08:07

They're again talking about obese (2MB) Agnus when they actually mean fatter Agnus (1MB)..

CRAZG · 21 October 2007, 06:44

What's the difference between 74LS* and 74HC* chips? Can I use the 74HC* chips instead for this purpose?

Chain · 21 October 2007, 12:45

74 family

15 October 2007, 19:17	#28
Chain A-Collector, repairments Join Date: Jul 2001 Location: Czech Rep. Age: 50 Posts: 1,536	hellyeah it works that way - 1 meg chip +0.5 meg fast but its unstable, dunno if its long wires or that damn solderless board always hangs or crashes (dark green screen, white dropouts, out of sync) after few seconds Last edited by Chain; 15 October 2007 at 22:25. Reason: typo

15 October 2007, 21:42	#31
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,864	Yeah, keep the wire lengths to a minimum and don't use breadboard, solder some sockets to a vero board instead and plug the logic glue into those.. :-) Last edited by Jope; 15 October 2007 at 21:49.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
A600 w/ 1MB Chip + 4MB Fast Ram = WHDLoad success rate?	Kenan	support.Hardware	7	08 May 2013 18:14
1Mb CHIP RAM hack and extra memory	orange	Hardware mods	3	29 June 2010 13:18
FOR SALE: A500 1MB upgrade and A500+ 1MB upgrade	clueless	MarketPlace	1	17 March 2010 11:21
UAEX - max 1MB Fast Ram	Zetr0	support.OtherUAE	4	20 August 2008 02:37
a4000/40, 1mb chip ?!	aix	support.Hardware	9	08 July 2006 17:35

31 August 2007, 13:45	#21
Chain A-Collector, repairments Join Date: Jul 2001 Location: Czech Rep. Age: 50 Posts: 1,536	im pretty sure your board does not have this logic. without that you will be stuck with 1mb chip/512+512, nothing more

31 August 2007, 14:38	#22
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,864	Zetro, you're talking about a different thing than Chain.. How I understood this: Zetro: solder RAM chips to motherboard for 1MB CHIP Chain's question + the schematic Wilen dug up: solder RAM chips to motherboard for 1MB CHIP and do a modification (per the schematic) to be able to have 512kB slow FAST in the trapdoor + 1MB CHIP on the mobo for a total of 1.5MB of internal memory.

31 August 2007, 17:14	#23
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	AHhhhhhhhhhhhhhhhhhh indeedy i was getting confused!!!!! sorry about that guys... thanks jope

25 September 2007, 13:56	#24
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	@Chain How are you getting on with this?

25 September 2007, 14:21	#25
DrF Blessed A1200 Of TeH Rat Join Date: Aug 2007 Location: Bham, UK Age: 42 Posts: 496	I am sure I seen a even more weird hack years ago, where they ended up stacking the RAM chips on top of each other and then there was a crap load of wire everywhere, needless to say I never tried it...

25 September 2007, 14:57	#26
Chain A-Collector, repairments Join Date: Jul 2001 Location: Czech Rep. Age: 50 Posts: 1,536	i dont want it piggybackin connected, as you cant fit keyboard back im still searching for 74f02 part in smd (i know i can substitute it but it will be one more chip)

06 October 2007, 09:28	#27
CRAZG 2 heads are more than 1 Join Date: May 2007 Location: Tauranga / New Zealand Posts: 38	I am trying this on my 6a boards (2) but so far have only soldered the new ram in place. I am a little confused about the effect of these jumpers etc. As I understand there are two scenarios here; one where you add 512k chip and this disables the expansion? and one where you add 512k ?fast? and leave the expansion slot enabled? I would like to leave the expansion enabled and have 1500k if possible.

15 October 2007, 19:45	#30
Chain A-Collector, repairments Join Date: Jul 2001 Location: Czech Rep. Age: 50 Posts: 1,536	i wil try to replace 74LowStability08 with 74Faith08, but tomorrow

15 October 2007, 22:00	#32
Zetr0 Ya' like it Retr0? Join Date: Jul 2005 Location: United Kingdom Age: 49 Posts: 9,768	so how does one get 2MB chip ram on an R6A A500 ? anyone got any techs?

15 October 2007, 22:22	#33
Chain A-Collector, repairments Join Date: Jul 2001 Location: Czech Rep. Age: 50 Posts: 1,536	i only know something about replacing 256x4 chips with 1mx4 chips, replacing agnus and A LOT of rewiring thats all. no schematic, not even a clue

16 October 2007, 00:38	#35
Eclipse Turpentine Join Date: Oct 2007 Location: Kent, United Kingdom Posts: 744	Don't know if this helps. http://webcebi.com/Amiga/

16 October 2007, 08:05	#36
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,864	That is not it. You need to do a lot more more cutting and rewiring to fit the 2MB Agnus on the A500 motherboard.. It is doable, I have seen instructions, but I have no idea where it was.. Perhaps in some magazine.

17 October 2007, 08:07	#38
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,864	They're again talking about obese (2MB) Agnus when they actually mean fatter Agnus (1MB)..

21 October 2007, 06:44	#39
CRAZG 2 heads are more than 1 Join Date: May 2007 Location: Tauranga / New Zealand Posts: 38	What's the difference between 74LS* and 74HC* chips? Can I use the 74HC* chips instead for this purpose?

21 October 2007, 12:45	#40
Chain A-Collector, repairments Join Date: Jul 2001 Location: Czech Rep. Age: 50 Posts: 1,536	74 family

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