A500 Rev 3 Mother board 1meg chip ram hacks.
Adam Kowalczyk
seen any for the rev 3 mother boards. Hard to believe, but yes I have one
of the first A500's. You know even the original power suppy was a true
transformer design rather than a switching power supply. That was just an
aside. Anyone with a REV 3 hack please send me the details. I've owned my
Amiga 500 since '87 and completely missed out on the fact the 8370 Fat Agnus
supported 1meg chip ram.
Adam Kowalczyk
Ross Vumbaca
The reason that the rev 3 mainboard has no Agnus hack is because the
8370 Agnus does NOT support 1 meg chip ram, so what's the point of the
hack?? ;-)
My Rev 6 1991 A500 (plus all my other A500 PSUs) are a transformer
design, I've never had a switcing type, so I wonder why everyone else
has.. The only switching one I have is the A600 one.
Regards,
Ross..
--
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address.*
Ross Vumbaca, a 'poor' Uni student at USyd.edu.au
http://www.fl.net.au/~rossv
Running on an Amiga 3000 (030/25), ECS, 8Mb Fast, 2Mb Chip, HD FDD
SCSI HDD's (never mind their size), Kickstart 3.1 (40.68), OS 3.5,
Linux 2.0 (RedHat 5.1), C= A2065 and an Opalvision card
- ("Designed in Australia", and keeping the Zorro bus populated).
--
Adam Kowalczyk
I've got a Rev 5 motherboard with an 8370 with the 1Meg chipram hack and it
shows that there is 1meg of chip ram. This could be a case of an 8372a with
an 8370 label. Besides, I do have an 8372b coming my way and was curious if
there was an equivalent hack for the Rev 3 motherboard. As far as the
transformer style power supply, Commodore must have had several suppliers
making different power supplies to the same spec.
Ross Vumbaca <ro...@fl.net.au> wrote in message
news:396054D7...@fl.net.au...
Adam Kowalczyk
8370, it has address lines a1 through a19. This is enough address lines to
address 512k addresses. Since the 8370 uses 16 data lines...is the 8370 a
512K device or a 1meg device if you use 8bits to normalize after all a byte
is 8 bits? Just curious for an answer.
Adam
Adam Kowalczyk
> That would be unlikely. The 8370 definitely only supports 512K chipram.
> There are ways to make the A500 think it has 1 Mb chip with an 8370, but
as
> soon as the second 512K is used as chipram by the system the Amiga will
> guru.
>
This is probably the case. I will see if I get the machine to guru after
the first 512K ram is gone.
> As far as the
> >transformer style power supply, Commodore must have had several suppliers
> >making different power supplies to the same spec.
>
> All the A500 PSU's that I've seen have been the same (transformer,
switching
> type), in Australia anyway.
>
> Regards,
>
> Clockmeister.
Back in '88 I had a small disaster with my A500. The A520 I had plugged
into the video port had come loose (probably forgot to tighten the thumb
screws) and my machine was dead. Looking at the motherboard, it seems they
may have replaced the video hybrid component (unless there was a problem
with it at the factory). The power supply that came with my A500 was also
toast. When I picked up my repaired unit, the power suppy was a heck of a
lot lighter than it originally was. Lighter to the point I felt something
was missing and was truly shocked when it powered on. In Canada (which is
where I am) there must have been two styles of the power supplies. I'll
call them heavy and light which I assume was based on the fact that the
original contained a large transformer while the new one must be some type
of switching power supply.
As an aside I have an 8372b coming which will be used in conjunction with a
DIY 2meg chipram expansion. This brings me to the fact that I'm still
curious if there is a hack for the Rev 3 motherboard to install an 8372a 1
meg chip (which I do have one of them lying around here somewhere)
Adam
K. C. Lee
>
> I've seen the hacks for rev 5 and rev 6 mb 1meg chip ram hacks, but I've not
> seen any for the rev 3 mother boards. Hard to believe, but yes I have one
> of the first A500's. You know even the original power suppy was a true
I got one rev 4 (or is it rev 3 ?) A500 motheboard that I bought for
$10.
I have replaced the Agnus with a 8375B and added the 2 meg of Chip using
two
30pin 1Mx8 simm soldered with wires to the expansion port. To make life
easier
the onboard 512K are disabled. I modified by comparing the A500 and
A500+
schematic.
I own an Agnus that supports only 512K of chip ram. Now that got to be
old.
K. C. Lee
Clockmeister
Adam Kowalczyk wrote in message ...
>Ross,
>
>I've got a Rev 5 motherboard with an 8370 with the 1Meg chipram hack and it
>shows that there is 1meg of chip ram. This could be a case of an 8372a
with
>an 8370 label.
That would be unlikely. The 8370 definitely only supports 512K chipram.
There are ways to make the A500 think it has 1 Mb chip with an 8370, but as
soon as the second 512K is used as chipram by the system the Amiga will
guru.
Besides, I do have an 8372b coming my way and was curious if
>there was an equivalent hack for the Rev 3 motherboard.
The 8372b isn't pin compatible with the 8370. It would involve a fair bit of
hacking.
As far as the
>transformer style power supply, Commodore must have had several suppliers
>making different power supplies to the same spec.
All the A500 PSU's that I've seen have been the same (transformer, switching
type), in Australia anyway.
Regards,
Clockmeister.
>Ross Vumbaca <ro...@fl.net.au> wrote in message
>news:396054D7...@fl.net.au...
>> Hi,
>>
>> Adam Kowalczyk wrote:
>>
>> > I've seen the hacks for rev 5 and rev 6 mb 1meg chip ram hacks, but
I've
>not
>> > seen any for the rev 3 mother boards. Hard to believe, but yes I have
>one
>> > of the first A500's. You know even the original power suppy was a true
Clockmeister
Adam Kowalczyk wrote in message ...
>
>> That would be unlikely. The 8370 definitely only supports 512K chipram.
>> There are ways to make the A500 think it has 1 Mb chip with an 8370, but
>as
>> soon as the second 512K is used as chipram by the system the Amiga will
>> guru.
>>
>the first 512K ram is gone.
>
>> >transformer style power supply, Commodore must have had several
suppliers
>> >making different power supplies to the same spec.
>>
>> All the A500 PSU's that I've seen have been the same (transformer,
>switching
>> type), in Australia anyway.
>>
>> Regards,
>>
>> Clockmeister.
>
>into the video port had come loose (probably forgot to tighten the thumb
>screws) and my machine was dead. Looking at the motherboard, it seems they
>may have replaced the video hybrid component (unless there was a problem
>with it at the factory). The power supply that came with my A500 was also
>toast. When I picked up my repaired unit, the power suppy was a heck of a
>lot lighter than it originally was. Lighter to the point I felt something
>was missing and was truly shocked when it powered on. In Canada (which is
>where I am) there must have been two styles of the power supplies. I'll
>call them heavy and light which I assume was based on the fact that the
>original contained a large transformer while the new one must be some type
>of switching power supply.
That is quite possible. Commodore probably sourced a cheaper alternative at
some point, and that being what you ended up with.
>
>As an aside I have an 8372b coming which will be used in conjunction with a
>DIY 2meg chipram expansion. This brings me to the fact that I'm still
>curious if there is a hack for the Rev 3 motherboard to install an 8372a 1
>meg chip (which I do have one of them lying around here somewhere)
>
I haven't seen a 8372a/1Mb chipram hack for early Rev 3 motherboards,
probably because it would require major surgery. The motherboard RAM won't
work with the 8372B so you would have to find a way to incorporate SIMM or
44256 DRAM banks.
Regards,
Clockmeister.
Ross Vumbaca
"K. C. Lee" wrote:
> I got one rev 4 (or is it rev 3 ?) A500 motheboard that I bought for
> $10.
> I have replaced the Agnus with a 8375B and added the 2 meg of Chip using
> two
> 30pin 1Mx8 simm soldered with wires to the expansion port. To make life
> easier
> the onboard 512K are disabled. I modified by comparing the A500 and
> A500+
> schematic.
Wow cool hack.. ;-).. But did you solder the SIMMs to the expansion port
sidebus, or to the trapdoor slot? I've got the A500 schematics, and I
don't think it would be possible to solder the chip mem to the sidebus
expansion port..
K. C. Lee
>
> Wow cool hack.. ;-).. But did you solder the SIMMs to the expansion port
> sidebus, or to the trapdoor slot? I've got the A500 schematics, and I
> don't think it would be possible to solder the chip mem to the sidebus
> expansion port..
I solder the SIMMs to the trapdoor slot with 2" wires. 30 pin SIMM was a
lot cheaper than 2M of trapdoor memory. There is no access to the chip
memory bus from the expansion port.
> Regards,
>
> Ross..
K. C. Lee
K. C. Lee
>
> I don't suppose that you have a schematic for that cool hack do you?.
Nope. I looked at the A500 and A500+ schmatics and solder as I go.
For the $10 I paid for the motherboard and the 30 pin SIMM, I figure
what the heck. There were only a few tracks that I have to cut &
solder wires to on the motherboard. The SIMMs save quite a bit of
headache of wiring your memory in parallel and it was cheap. Getting
the socket was another problem. ;)
I even solder in one of those A1200 battery clock module that I bought
onto the trapdoor port. It helps when they are using the same chip.
> Clockmeister.
K. C. Lee
Clockmeister
K. C. Lee wrote in message <39611B70...@freenet.carleton.ca>...
>Adam Kowalczyk wrote:
>>
>> I've seen the hacks for rev 5 and rev 6 mb 1meg chip ram hacks, but I've
not
>> seen any for the rev 3 mother boards. Hard to believe, but yes I have
one
>> of the first A500's. You know even the original power suppy was a true
>
>$10.
>I have replaced the Agnus with a 8375B and added the 2 meg of Chip using
>two
>30pin 1Mx8 simm soldered with wires to the expansion port. To make life
>easier
>the onboard 512K are disabled. I modified by comparing the A500 and
>A500+
>schematic.
>
>old.
>
I don't suppose that you have a schematic for that cool hack do you?.
Regards,
Clockmeister.
K. C. Lee
>
> I couldn't find much info online on how to arrange SIMMs to work together.
> Any usefull links?.
Do a search on Deja News (use OLD news). There are just too much junk on
the net these days.
For you reference, here is one that I have archived on my CD:
K. C. Lee
(Note the date on that... ;)
--------->8--------------->8------------------>8--------------------------------
From: Jan_H...@augs2.UUCP (Jan Holler)
Newsgroups: comp.sys.amiga.hardware
Subject: RE> Need SIMM pin list!
Message-ID: <Jan_Hol...@augs2.UUCP>
Date: 26 May 92 22:55:30 GMT
Organization: Amiga Usergroup Switzerland
Lines: 92
In article <1992May...@shamash.cdc.com>, a...@shamash.cdc.com
( GSD Advanced Packing/Processes) writes:
>Does anyone have a pin out listing of 30 pin SIMM modules?
>I'm building the PD memory expansion project, which has a schematic
>which shows pin names but no pin numbers.
>If someone would supply them, I would really appreciate it!
>Thanks in advance..
>Mike Lundberg
>a...@shamash.cdc.com
Hi Mike,
please be the next time a little bit more specific. 30pin SIMM Modules
exit in various versions. Basically, there refer all to 4Mx9 (or 16Mx9).
I will list this one and point out the differences.
Here we go:
Pins 4Mx9 4Mx8 1Mx9 1Mx8 256Kx9 256Kx8 Pins (Meaning)
1 Vcc 1 Power +5V
2 _CAS 2 Column Addr. Strobe
3 DQ0 3 Data In/Out
4 A0 4 Address Input
5 A1 5
6 DQ1 6
7 A2 7
8 A3 8
9 Vss 9 GND
10 DQ2 10
11 A4 11
12 A5 12
13 DQ3 13
14 A6 14
15 A7 15
16 DQ4 16
17 A8 17
18 A9 NC NC 18 NC = No Connection
19 A10 NC NC 19
20 DQ5 20
21 _W 21 Read/Write Input
22 Vss 22 GND
23 DQ6 23
24 NC 24
25 DQ7 25
26 PQ NC NC NC 26 Data out for Parity
27 _RAS 27 Row Addr. Strobe
28 _PCAS NC NC NC 28 _CAS for Parity
29 PD NC NC NC 29 Data in for Parity
30 Vcc 30 Power +5V
I hope that serves your needs!
ALSO:
In article <1B0A3...@saarag.saar.sub.org>
m_sc...@saarag.saar.sub.org
(Martin Schulze) writes:
> From: visc...@cis.ohio-state.edu (Mark Visconti)
>
> Is it possible to use 1x9's and 49's in place of 1x8's or 4x8's ?
Yes, basically it works. As you can see, those SIMMs differ only in Pin
26,
28 & Pin 29. (Data our for Parity, column address strobe for Parity,
Data
in for Parity).
You should make sure befor you plug them in the sockes, that the
manufacturer of the board you want to expand, didn't pull those up to
Vcc
or down to Vss (what he shouldn't anyway). If your board has NC for Pin
26,
28,29. There is no problem and nor risk at all.
Jan Holler - Bern, Swizerland
uunet!cbmvax!cbmehq!cbmswi!augs1!augs2!Jan_Holler
"How can a computer ever be perfect? If not even human is!"
"Shouldn't we just sit and wait or does'nt the sun go down anymore?"
-- DLG Pro v0.991
Clockmeister
K. C. Lee wrote in message <39627A01...@freenet.carleton.ca>...
>Clockmeister wrote:
>>
>> I don't suppose that you have a schematic for that cool hack do you?.
>
It's just that this question has come up a few times (hacking SIMMs to work
in an A500) that it would have been great if you had a schematic of your
hack and uploaded it to Aminet (hint, hint :-)
>For the $10 I paid for the motherboard and the 30 pin SIMM, I figure
>what the heck. There were only a few tracks that I have to cut &
>solder wires to on the motherboard. The SIMMs save quite a bit of
>headache of wiring your memory in parallel and it was cheap. Getting
>the socket was another problem. ;)
I couldn't find much info online on how to arrange SIMMs to work together.
Any usefull links?.
>I even solder in one of those A1200 battery clock module that I bought
>onto the trapdoor port. It helps when they are using the same chip.
>
Cool.
Regards,
Clockmeister.
Clockmeister
Thanks for the tip ;-)
Regards,
Clockmeister.
Greg Tallent
> I've seen the hacks for rev 5 and rev 6 mb 1meg chip ram hacks, but I've not
> seen any for the rev 3 mother boards. Hard to believe, but yes I have one
> of the first A500's. You know even the original power suppy was a true
> aside. Anyone with a REV 3 hack please send me the details. I've owned my
> Amiga 500 since '87 and completely missed out on the fact the 8370 Fat Agnus
> supported 1meg chip ram.
> Adam Kowalczyk
The 8370 only supports 512K chip RAM, you need the 8372A to use 1 Meg of chip.
<tsb>
Greg Tallent |Amiga2000 GVP 040/33mhz/3.5 72 megs,9 gig/BuddhaIDE|
gwt at gte.net |Zoom 56k, Syjet, Zip, Picasso II 2Meg, Plextor CD-R|
And now, 55 minutes of uninterrupted commercials...
Greg Tallent
> Ross,
> I've got a Rev 5 motherboard with an 8370 with the 1Meg chipram hack and it
> shows that there is 1meg of chip ram. This could be a case of an 8372a with
> an 8370 label. Besides, I do have an 8372b coming my way and was curious if
> there was an equivalent hack for the Rev 3 motherboard. As far as the
> transformer style power supply, Commodore must have had several suppliers
> making different power supplies to the same spec.
The 8372B is a 2 Meg Agnus chip, not a 1 Meg chip.
It's also not pin compatible with either the 8370 or 8372A Agnus chips.
Also, you can use a Mini Megachip or a Megachip 2000 WITHOUT doing the 1 Meg
conversion but you'll only get 1.5 Megs of chip RAM. I ran my A500 for a
couple of months without the A501 when it decided to croak on me and it ran
fine but it only had 1.5 Megs or chip RAM.
<tsb>
Greg Tallent |Amiga2000 GVP 040/33mhz/3.5 72 megs,9 gig/BuddhaIDE|
gwt at gte.net |Zoom 56k, Syjet, Zip, Picasso II 2Meg, Plextor CD-R|
A NAVY flier's nightmare ... NO CARRIER