A500 trapdoor memory: free design - Page 26

Vesuri · 30 September 2019, 22:36

I recently bought a version of this card from AMIGAstore.eu and got it installed in the 0.5MB chip + 1.5MB slow configuration. (Thanks Jope for helping debug my JP2/JP7A brainfart!) Unfortunately neither the OS or the Amiga Test Kit find the RTC on board. SetClock RESET doesn't do the trick. I've measured that the Epson RTC-72421A chip does get 3V from the battery (pins 9 and 18) but other than that I'm not sure where to look at. Any ideas what might cause the RTC not to be found?

I did have the card installed for a moment with an incorrect JP2/JP7A setup. May this have killed the RTC on the card? During the installation process the TOD part of my CIAA also died. Not sure if it's related or not.

katarakt · 01 October 2019, 19:56

If resetting the clock does not help, then something may be damaged. Can you see the RTC with keirf systest?

solarmon · 02 October 2019, 06:30

Quote:

Originally Posted by Vesuri

I recently bought a version of this card from AMIGAstore.eu and got it installed in the 0.5MB chip + 1.5MB slow configuration. (Thanks Jope for helping debug my JP2/JP7A brainfart!) Unfortunately neither the OS or the Amiga Test Kit find the RTC on board. SetClock RESET doesn't do the trick. I've measured that the Epson RTC-72421A chip does get 3V from the battery (pins 9 and 18) but other than that I'm not sure where to look at. Any ideas what might cause the RTC not to be found?

I did have the card installed for a moment with an incorrect JP2/JP7A setup. May this have killed the RTC on the card? During the installation process the TOD part of my CIAA also died. Not sure if it's related or not.

Is this an A500 or A500+ the card is installed in?

If A500+ there is also a JP9 jumper that tells the system to look for the internal RTC (default) or the external RTC.

Vesuri · 02 October 2019, 16:30

Quote:

Originally Posted by katarakt

Can you see the RTC with keirf systest?

No, I cannot.

Quote:

Originally Posted by solarmon

Is this an A500 or A500+ the card is installed in?

This is an A500 rev6A.

I used to have a Microbotics M501 512k card with an RTC installed and that one did work but that was prior to the JP2/JP7A changes. I haven't tested it again afterwards - would that require undoing the JP2 modification?

I swapped the CIAs and that moved the TOD problem to CIAB, making clock work again in the OS. However, that didn't affect the RTC not being found.

solarmon · 02 October 2019, 17:27

The clock read (_CLKRD) and write (_CLKWR) signals goes to Gary - pins 22 and 23.

Try cleaning the pins and socket of Gary.

solarmon · 02 October 2019, 22:37

And, if you can get it to your A500, try the RestartClock tool:

http://thomas-rapp.homepage.t-online...startClock.lha

I suggest the easiest method, is to us a Gotek drive with a Workbench ADF, and another ADF created with Directory Opus and put RestartClock on it.

You can then boot up the Workbench ADF, start a CLI/shell, swap to the other ADF, and run the RestartClock command.

Vesuri · 03 October 2019, 10:53

Quote:

Originally Posted by solarmon

And, if you can get it to your A500, try the RestartClock tool

Thanks! Tried it but it didn't do anything. I could write my own code to access the RTC through DC0000-DCFFFF but I doubt this would be that beneficial if the SysTest (for example) won't find the clock at all.

solarmon · 03 October 2019, 11:41

So maybe you could check the chip select trace (_XCLKCS) to make sure it is OK and asserted (_XCLKCS is active low).

solarmon · 03 October 2019, 12:22

And looking at the schematics/gerbers - there seems to be a jumper to enable the clock? Is this jumper enabled on your board?

Vesuri · 03 October 2019, 23:02

Quote:

Originally Posted by solarmon

The clock read (_CLKRD) and write (_CLKWR) signals goes to Gary - pins 22 and 23.

_CLKRD on Gary pin 22 is connected to pin 8 of the RTC chip (through pin 49 of the trapdoor expansion connector). _CLKWR on Gary pin 23 is connected to pin 10 of the RTC chip. As far as I understand these look correct.

Quote:

Originally Posted by solarmon

So maybe you could check the chip select trace (_XCLKCS) to make sure it is OK and asserted (_XCLKCS is active low).

If I understand correctly, _XCLKCS is pin 33 on the trapdoor expansion connector and is connected to ground on the motherboard side and to pin 2 of the RTC chip. This seems to be the case in my system.

Quote:

Originally Posted by solarmon

And looking at the schematics/gerbers - there seems to be a jumper to enable the clock? Is this jumper enabled on your board?

It is. Here's a photo of the board:

One thing potentially worth mentioning: the system does have a TerribleFire TF530 installed. However, an another RTC did work with it without issues.

solarmon · 04 October 2019, 07:58

Have you tried without the TF? And do you still have the other RTC to try out. At least you can rule out your A500 motherboard.

When I had similar RTC issues on my A500+ - it was not found or the clock was not ticking - I tried reflowing the pins of the sockets and components. But this was on a battery damaged A500+

Eventually I replaced the RTC chip itself and it was working and stable since then.

It is a shame the RTC chip on your memory board is not socketed, but you can still replace it if you have the tools and skillset. However, since it is new you might want to consider returning it and getting a replacement, but you should try to rule out your A500 motherboard first.

Vesuri · 04 October 2019, 11:51

Quote:

Originally Posted by solarmon

Have you tried without the TF? And do you still have the other RTC to try out. At least you can rule out your A500 motherboard.

The RTC in the old card works still fine (with the TF installed). I haven't tried the new card yet without the TF but I guess it would be surprising if that was the problem since the old one works - especially since this was advertised by AMIGAstore as the perfect companion for the TF

Quote:

Originally Posted by solarmon

It is a shame the RTC chip on your memory board is not socketed, but you can still replace it if you have the tools and skillset.

Indeed - I don't feel confident replacing it myself with my tools and skillset.

Quote:

Originally Posted by solarmon

However, since it is new you might want to consider returning it and getting a replacement, but you should try to rule out your A500 motherboard first.

Yes, I've already contacted AMIGAstore for advice but haven't heard back from them yet.

solarmon · 08 October 2019, 14:41

With the board in the Amiga and powered on, what is the voltage at the RTC chip? It needs be within usually 2V to 6V. If it is out of range - i.e. if it is higher than 6V the RTC chip with not work.

I just found this out with one of my memory expansion cards. With the battery removed and card plugged in and powered by the Amiga, the RTC chip was getting 8.1V, due to the 12V source.

CrowStudio · 15 November 2019, 20:09

I had the exact same problem with my RTC not working on the same expansion board, it turned out to be a faulty IC.
By chance I happened to have a RTC in an old memory card that was in a socket. I took that IC and piggy backed it on the suspected faulty RTC on my expansion board, and to my surprise it worked!

So if you have not solved your issue yet, and happen to have a RTC in a socket, try to piggy back it ;-)

*edit* be sure that you have a tight fit when placing the other RTC over the RTC on the expanison, see picture *edit*

redblade · 25 November 2019, 19:34

Hi guys. So the most max RAM you can have on a A500 with out using a gary adapter is just 512k RAM? and on an A500+ that 512k ram goes straight to $80000-$fffff instead of $c00000 like on the A500?

Thanks

demolition · 25 November 2019, 20:55

Quote:

Originally Posted by redblade

Hi guys. So the most max RAM you can have on a A500 with out using a gary adapter is just 512k RAM? and on an A500+ that 512k ram goes straight to $80000-$fffff instead of $c00000 like on the A500?

You can fill up the memory space (>~12MB) if you use the CPU socket or the left-side expansion connector but if you mean only using the trapdoor connector, then a rev. 6 or older A500 will make it possible to add 512k. A rev. 8 A500 (which shares the PCB with an A500+) should allow for 1MB in the trapdoor (taking the machine to 1.5MB chip).

Jope · 26 November 2019, 08:23

Quote:

Originally Posted by redblade

Hi guys. So the most max RAM you can have on a A500 with out using a gary adapter is just 512k RAM?

In the trapdoor, yes. You can fit 8MB of real fast in the AmigaBUS on the left side of the machine.

Quote:

and on an A500+ that 512k ram goes straight to $80000-$fffff instead of $c00000 like on the A500?

Yes, per default it is tacked on to the chip ram area, but not at $80000, that is already on the motherboard. It goes to $100000-17ffff.

redblade · 26 November 2019, 08:43

Thanks, Yes I was meaning just in the trap door. Most searches just showed a 512k Ram expansion, memory maps, or expansions with the gary adaptors.

Mainly wondering because those other expansions looked like they would have voided the warranty back in the 80s early 90s.

I see a post on this board by zetro regarding bank switching.

SukkoPera · 26 November 2019, 08:49

Just a note: on an A500+, you can have 1 MB extra chip RAM in the trapdoor, and this board also works for that.

MalleB · 05 May 2020, 13:52

katarakt made me aware that the Rev C6 (SOJ40) is still documented here as *UNTESTED*
http://eab.abime.net/showpost.php?p=1131907&postcount=2

The Rev C6 works great as a 512k Slowram Extension on the A500 Rev.5 and Rev.6

And I use successfully the Rev C6 as a 1M Chipram Extension on the A500 Rev.8

I found the SOJ40 memory chips on an old AGP graphics card

15 November 2019, 20:09	#514
CrowStudio Registered User Join Date: Sep 2019 Location: Göteborg / Sweden Posts: 32	I had the exact same problem with my RTC not working on the same expansion board, it turned out to be a faulty IC. By chance I happened to have a RTC in an old memory card that was in a socket. I took that IC and piggy backed it on the suspected faulty RTC on my expansion board, and to my surprise it worked! So if you have not solved your issue yet, and happen to have a RTC in a socket, try to piggy back it ;-) edit be sure that you have a tight fit when placing the other RTC over the RTC on the expanison, see picture edit Attached Thumbnails Last edited by CrowStudio; 15 November 2019 at 20:15. Reason: adding picture

05 May 2020, 13:52	#520
MalleB Registered User Join Date: May 2020 Location: Berlin, Germany Posts: 2	katarakt made me aware that the Rev C6 (SOJ40) is still documented here as UNTESTED http://eab.abime.net/showpost.php?p=1131907&postcount=2 The Rev C6 works great as a 512k Slowram Extension on the A500 Rev.5 and Rev.6 And I use successfully the Rev C6 as a 1M Chipram Extension on the A500 Rev.8 I found the SOJ40 memory chips on an old AGP graphics card Attached Thumbnails Last edited by MalleB; 05 May 2020 at 13:58.

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30 September 2019, 22:36	#501
Vesuri Registered User Join Date: Sep 2019 Location: Amsterdam / The Netherlands Posts: 48	I recently bought a version of this card from AMIGAstore.eu and got it installed in the 0.5MB chip + 1.5MB slow configuration. (Thanks Jope for helping debug my JP2/JP7A brainfart!) Unfortunately neither the OS or the Amiga Test Kit find the RTC on board. SetClock RESET doesn't do the trick. I've measured that the Epson RTC-72421A chip does get 3V from the battery (pins 9 and 18) but other than that I'm not sure where to look at. Any ideas what might cause the RTC not to be found? I did have the card installed for a moment with an incorrect JP2/JP7A setup. May this have killed the RTC on the card? During the installation process the TOD part of my CIAA also died. Not sure if it's related or not.

01 October 2019, 19:56	#502
katarakt Registered User Join Date: Jul 2017 Location: Germany Posts: 205	If resetting the clock does not help, then something may be damaged. Can you see the RTC with keirf systest?

02 October 2019, 17:27	#505
solarmon Registered User Join Date: Dec 2018 Location: UK Posts: 1,715	The clock read (_CLKRD) and write (_CLKWR) signals goes to Gary - pins 22 and 23. Try cleaning the pins and socket of Gary.

02 October 2019, 22:37	#506
solarmon Registered User Join Date: Dec 2018 Location: UK Posts: 1,715	And, if you can get it to your A500, try the RestartClock tool: http://thomas-rapp.homepage.t-online...startClock.lha I suggest the easiest method, is to us a Gotek drive with a Workbench ADF, and another ADF created with Directory Opus and put RestartClock on it. You can then boot up the Workbench ADF, start a CLI/shell, swap to the other ADF, and run the RestartClock command.

03 October 2019, 11:41	#508
solarmon Registered User Join Date: Dec 2018 Location: UK Posts: 1,715	So maybe you could check the chip select trace (_XCLKCS) to make sure it is OK and asserted (_XCLKCS is active low).

03 October 2019, 12:22	#509
solarmon Registered User Join Date: Dec 2018 Location: UK Posts: 1,715	And looking at the schematics/gerbers - there seems to be a jumper to enable the clock? Is this jumper enabled on your board?

04 October 2019, 07:58	#511
solarmon Registered User Join Date: Dec 2018 Location: UK Posts: 1,715	Have you tried without the TF? And do you still have the other RTC to try out. At least you can rule out your A500 motherboard. When I had similar RTC issues on my A500+ - it was not found or the clock was not ticking - I tried reflowing the pins of the sockets and components. But this was on a battery damaged A500+ Eventually I replaced the RTC chip itself and it was working and stable since then. It is a shame the RTC chip on your memory board is not socketed, but you can still replace it if you have the tools and skillset. However, since it is new you might want to consider returning it and getting a replacement, but you should try to rule out your A500 motherboard first.

08 October 2019, 14:41	#513
solarmon Registered User Join Date: Dec 2018 Location: UK Posts: 1,715	With the board in the Amiga and powered on, what is the voltage at the RTC chip? It needs be within usually 2V to 6V. If it is out of range - i.e. if it is higher than 6V the RTC chip with not work. I just found this out with one of my memory expansion cards. With the battery removed and card plugged in and powered by the Amiga, the RTC chip was getting 8.1V, due to the 12V source.

25 November 2019, 19:34	#515
redblade Zone Friend Join Date: Mar 2004 Location: Middle Earth Age: 40 Posts: 2,127	Hi guys. So the most max RAM you can have on a A500 with out using a gary adapter is just 512k RAM? and on an A500+ that 512k ram goes straight to $80000-$fffff instead of $c00000 like on the A500? Thanks

26 November 2019, 08:43	#518
redblade Zone Friend Join Date: Mar 2004 Location: Middle Earth Age: 40 Posts: 2,127	Thanks, Yes I was meaning just in the trap door. Most searches just showed a 512k Ram expansion, memory maps, or expansions with the gary adaptors. Mainly wondering because those other expansions looked like they would have voided the warranty back in the 80s early 90s. I see a post on this board by zetro regarding bank switching.

26 November 2019, 08:49	#519
SukkoPera Mighty Pirate Join Date: Dec 2017 Location: On the borderline Age: 44 Posts: 177	Just a note: on an A500+, you can have 1 MB extra chip RAM in the trapdoor, and this board also works for that.

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