X-4010 memory prob

[Mr Lurch]

Evening all,

I have a stock System 80 with 16k of memory.

I also have a X-4010 expansion unit with the X-4016 RAM card.

The RAM card is full. All 16 sockets have 4116 chips.

However PRINT MEM only reports 32K

Just so we're on the same page - there are two rows on RAM sockets. I'll call the one closest to the edge connector Row 1 and the one under that Row 2.

These are the scenarios I've tested:

No Expansion connected - 16k (correct!)

With the expansion connected:

Both rows full - 32k

Only row 1 - 32k

Only row 2 - 32k

!!

Its like there is some limit I cannot find that tops out at 32k

*Any* ideas?

(yes, I've just spent the last half hour on FB chat with Terry :) )

Cheers,

Jase

[Peter Nield]

Hi,

 

I had one of those cards.

 

https://www.classic-computers.org.nz/system-80/manuals_tm3_drawing%204.22_x-4016%20ram%20card%20schematics.jpg

 

It looks like the System 80 may have had some rudimentary memory management, and could use the either of the upper 16KB banks regardless of where it was.

 

Or you may have one or more faulty chips in the upper bank chips (if you have been carf

 

Or someone has been messing the jumpers (X2, X3) on the board near z30 and 31.

 

X2 is used to select where in the 16KB blocks each 16KB bank should appear (default connections select the upper two banks (pins 11 and 12 of Z30)

 

X3 affects the CAS strobe on the banks – default is all jumpers in place, but if 4Kb DRAM chips had been used, or to provide a 4KB memory hole within the expansion memory, the jumpers could be used to allow that as the X3 jumpers affect the 4KB blocks within the banks that are decoded for each of the 16KB banks.

 

Here’s an image of the X-4016 I had before I sold it with the X4010 I had.

top https://www.facebook.com/photo.php?fbid=10212435285369830&set=a.10212357188977469.1073741826.1012243787&type=3&theater

bottom https://www.facebook.com/photo.php?fbid=10212435286089848&set=a.10212357188977469.1073741826.1012243787&type=3&theater

 

OTOH, we had issues with some of the memory not refreshing correctly or the card  (last 256 or 128 bytes not being refreshed).  Despite (very expensive) replacement 4116’s and sending to DSE for service, never resolved that so just told NEWDOS/80 to ignore the last 256 bytes of memory to stop the whole disk copies from failing…

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[Lurch]

Thanks Peter.

We wondered if the dip switch banks did anything re: RAM. But I can find zero documentation on it. So if they have been played with; I'd have no idea :(

------ Original Message ------

From: "Peter Nield" <pj_n...@hotmail.com>

To: "eaca-di...@googlegroups.com" <eaca-di...@googlegroups.com>

Sent: 19/06/2018 9:44:38 PM

Subject: RE: X-4010 memory prob

Hi,

 

I had one of those cards.

 

https://www.classic-computers.org.nz/system-80/manuals_tm3_drawing%204.22_x-4016%20ram%20card%20schematics.jpg

 

It looks like the System 80 may have had some rudimentary memory management, and could use the either of the upper 16KB banks regardless of where it was.

 

Or you may have one or more faulty chips in the upper bank chips (if you have been carf

 

Or someone has been messing the jumpers (X2, X3) on the board near z30 and 31.

 

X2 is used to select where in the 16KB blocks each 16KB bank should appear (default connections select the upper two banks (pins 11 and 12 of Z30)

 

X3 affects the CAS strobe on the banks – default is all jumpers in place, but if 4Kb DRAM chips had been used, or to provide a 4KB memory hole within the expansion memory, the jumpers could be used to allow that as the X3 jumpers affect the 4KB blocks within the banks that are decoded for each of the 16KB banks.

 

Here’s an image of the X-4016 I had before I sold it with the X4010 I had.

top https://www.facebook.com/photo.php?fbid=10212435285369830&set=a.10212357188977469.1073741826.1012243787&type=3&theater

bottom https://www.facebook.com/photo.php?fbid=10212435286089848&set=a.10212357188977469.1073741826.1012243787&type=3&theater

 

OTOH, we had issues with some of the memory not refreshing correctly or the card  (last 256 or 128 bytes not being refreshed).  Despite (very expensive) replacement 4116’s and sending to DSE for service, never resolved that so just told NEWDOS/80 to ignore the last 256 bytes of memory to stop the whole disk copies from failing…

 

 

 

From: eaca-di...@googlegroups.com <eaca-di...@googlegroups.com> On Behalf Of Mr Lurch
Sent: Tuesday, 19 June 2018 10:23 PM
To: Eaca discussion <eaca-di...@googlegroups.com>
Subject: X-4010 memory prob

 

Evening all,

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[Mr Lurch]

I’m not sure if this is helpful, but here are photos of the two boards. 

Sent from my iPhone

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[Terry Stewart]

Incidentally, while on this topic...

If anyone has a scan of the manual (if there was one?) for the original expansion box (X-4010), I'd love to have it to add to the System 80 archive site. I have the manual for the later model (X-4020) and the circuit diagrams for X-4010 (as part of the System 80 technical manual) but no specific manual for the first version of the expansion interface. I assume there was one?

Terry

[Mr Lurch]

Ok - this *may* be nothing.

However in the Tech manual, on page 48 there is a board layout diagram

I note that there is a link drawn in "around" X1.

My PCB has a line there in the screen print; but no link.

[Mr Lurch]

I also note that on the photo of Peters, he has no link there either, BUT the traces from it seem to be cut.

https://scontent.fcbr1-1.fna.fbcdn.net/v/t31.0-8/r180/20232875_10212435285369830_2836548744800106938_o.jpg?_nc_cat=0&oh=32da665db309b1bb4226583bc745f758&oe=5BB64537

[Knut Roll-lund]

Hi

 

I would try PEEK'ing and POKE'ing, in rom basic, to establish if there is any memory. The ROM initiation scan will skip any failing area.

 

You need to specify address as a signed integer so -1=0xffff and -32768=0x8000 for PEEK and POKE. If it thinks it has 32K RAM -16384=0xC000

 

If you run a DOS I think there are setting for limiting used memory, it might be set up to not use all the RAM.

 

Short basic program to peek high ram repetitively may be easy to detect with oscilloscope to see selects are correct...

 

Knut :-)

--

[Leslie Ayling]

Hi Terry,

 

Hope you’re well?

 

The X4010 expander, and also the X4016 memory board are detailed in the

“Blue” System 80 Technical Manual Issue #3 on your website.

 

Starts at Page 113.

 

Cheers,

Leslie

--

[Terry Stewart]

Hi Leslie,

I'm, fine thanks.

>The X4010 expander, and also the X4016 memory board are detailed in the

>“Blue” System 80 Technical Manual Issue #3 on your website.

 

>Starts at Page 113.

Yes, I'd seen those diagrams there.  I wondered though if there was a separate manual for it, like there is for the X4020?

Terry

On Wed, Jun 20, 2018 at 10:03 PM, Leslie Ayling <lay...@bigpond.net.au> wrote:

Hi Terry,

 

Hope you’re well?

 

The X4010 expander, and also the X4016 memory board are detailed in the

“Blue” System 80 Technical Manual Issue #3 on your website.

 

Starts at Page 113.

 

Cheers,

Leslie

 

 

 

From: terry.st...@gmail.com [mailto:terry.stewart296a@gmail.com] On Behalf Of Terry Stewart
Sent: Wednesday, 20 June 2018 1:03 PM
To: eaca-discussion@googlegroups.com
Subject: Re: X-4010 memory prob

 

Incidentally, while on this topic...

 

If anyone has a scan of the manual (if there was one?) for the original expansion box (X-4010), I'd love to have it to add to the System 80 archive site. I have the manual for the later model (X-4020) and the circuit diagrams for X-4010 (as part of the System 80 technical manual) but no specific manual for the first version of the expansion interface. I assume there was one?

 

Terry

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