Atom duo 64k board issue

discussion of games, software, hardware & emulators relating to the Acorn Atom
Telemedic
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Atom duo 64k board issue

Postby Telemedic » Tue Feb 06, 2018 2:19 am

Hi guys, has anyone got any clue as to what’s what with these boards? When I received the machine, both wires b and c were soldered together and fitted to a socket other than specified in the manual. The machine worked but &top is 2902. According to the manual, it says solder wire c to pin 8 of ic 51. This is a 2114. It’s missing. The manual states remove ic’s 10 to 19 and repurpose them. It say nothing about removing ic 51 or 52. Both are empty. If I put wire c to pin 8 of ic 51, it won’t boot.if I fill ic 51 and 52 and apply pin c it won’t boot. If I leave wire c and b disconnected it boots with top at 2902. Am I missing something?


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oss003
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Re: Atom duo 64k board issue

Postby oss003 » Tue Feb 06, 2018 8:50 am

The TOP at #2902 is normal.
When there's RAM at #2900, the page is set at #2900 and the TOP is the location where vars are stored decelared with the DIM statement.
TOP = #2902 means that there's no program at #2900.
Don't get confused with the Beebs HIMEM command.

You can use the ram test to see if your card is working.

Code: Select all

 10 @=4;P.$12"ATOMIC MEMORY CHECKER"''
 20 P."     0000 0400 0800 0C00"'
 30 F.I=0TO#9FFFS.#1000;P.&I';N.
 40 F.Y=0TO9
 50  F.X=0TO3
 60   Z=Y*#1000+X*#400+9
 70   B=#8065+X*5+Y*#20
 80   A=!Z
 90   !Z=0;IF !Z<>0;!B=#8D8F9220;G.130
100   !Z=-1;IF !Z<>-1;!B=#8D8F9220;G.130
110   !B=#0D011220
120   !Z=A
130  N.
140 N.
150 END

Greetings
Kees

Telemedic
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Re: Atom duo 64k board issue

Postby Telemedic » Tue Feb 06, 2018 1:13 pm



No! That’s what I’m working from! It’s this that says where to connect b and c. When I do, it doesn’t boot!!

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1024MAK
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Re: Atom duo 64k board issue

Postby 1024MAK » Tue Feb 06, 2018 1:30 pm

Can you please post a close-up detailed photo of your RAM board.

Mark
For a "Complete BBC Games Archive" visit www.bbcmicro.co.uk NOW!
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Telemedic
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Re: Atom duo 64k board issue

Postby Telemedic » Tue Feb 06, 2018 2:10 pm

1024MAK wrote:Can you please post a close-up detailed photo of your RAM board.

Mark


No worries when I get home later, I will do :)

Telemedic
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Re: Atom duo 64k board issue

Postby Telemedic » Tue Feb 06, 2018 6:27 pm

As promised a pic of the 64k ram board.
8001385A-4E86-4CA8-8446-7A2BEEF231E9.jpeg
Memory board

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oss003
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Re: Atom duo 64k board issue

Postby oss003 » Tue Feb 06, 2018 7:06 pm

I think IC's 51 and 52 should be placed to have a non-moveable zeropage #0000-#03FF.
The zeropage selection, pin8 IC51, is needed to exclude this area on the 64 kB RAM board.
So, wire C is the zeropage exclusion signal.

Because the Atom can only address 32KB RAM, the 64KB on the board is divided in 2 blocks of 32KB.
You need a signal to switch these blocks and that can be done by PB0 of the 6522, pin 10 of 6522.
This means that wire B is used to select the RAM bank.

If wires B and C were soldered together and put into pin9 of IC5 (0V) means that zeropage and the first 32KB block are selected.
So only half of the 64KB is used.

Strange that the Atom won't boot with IC51/52 and the 64KB board installed.
Can you try to replace IC51/52 with some other 2114's?

If this isn't working, can you disconnect wires B and C and then run the RAM test?

Greetings
Kees

Telemedic
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Re: Atom duo 64k board issue

Postby Telemedic » Tue Feb 06, 2018 7:07 pm

oss003 wrote:The TOP at #2902 is normal.
When there's RAM at #2900, the page is set at #2900 and the TOP is the location where vars are stored decelared with the DIM statement.
TOP = #2902 means that there's no program at #2900.
Don't get confused with the Beebs HIMEM command.

You can use the ram test to see if your card is working.

Code: Select all

 10 @=4;P.$12"ATOMIC MEMORY CHECKER"''
 20 P."     0000 0400 0800 0C00"'
 30 F.I=0TO#9FFFS.#1000;P.&I';N.
 40 F.Y=0TO9
 50  F.X=0TO3
 60   Z=Y*#1000+X*#400+9
 70   B=#8065+X*5+Y*#20
 80   A=!Z
 90   !Z=0;IF !Z<>0;!B=#8D8F9220;G.130
100   !Z=-1;IF !Z<>-1;!B=#8D8F9220;G.130
110   !B=#0D011220
120   !Z=A
130  N.
140 N.
150 END

Greetings
Kees
Attachments
6E968EDA-62FE-48EF-978C-AF0879825F7A.jpeg
Output from program

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oss003
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Re: Atom duo 64k board issue

Postby oss003 » Tue Feb 06, 2018 7:25 pm

I think you typed #97FF instead of #9FFF in line 30, but that doesn't matter.
Looks like 32KB RAM is installed and working.

Is this with both wires disconnected and IC's 51/52 removed?

Greetings
Kees

Telemedic
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Re: Atom duo 64k board issue

Postby Telemedic » Tue Feb 06, 2018 7:31 pm

oss003 wrote:I think IC's 51 and 52 should be placed to have a non-moveable zeropage #0000-#03FF.
The zeropage selection, pin8 IC51, is needed to exclude this area on the 64 kB RAM board.
So, wire C is the zeropage exclusion signal.

Because the Atom can only address 32KB RAM, the 64KB on the board is divided in 2 blocks of 32KB.
You need a signal to switch these blocks and that can be done by PB0 of the 6522, pin 10 of 6522.
This means that wire B is used to select the RAM bank.

If wires B and C were soldered together and put into pin9 of IC5 (0V) means that zeropage and the first 32KB block are selected.
So only half of the 64KB is used.

Strange that the Atom won't boot with IC51/52 and the 64KB board installed.
Can you try to replace IC51/52 with some other 2114's?

If this isn't working, can you disconnect wires B and C and then run the RAM test?

Greetings
Kees


You certainly know your stuff, and have a way of explaining thing so I understand:) I think from the test program, I have 32k available. So I’m going to lock it off. The 64k think is a little gimmicky for me. Also the the atom language is a bit different to me, I’m gonna be fine with 32k for a bit while I get aquatinted with this new (to me) flavour!
Attachments
C7E7A198-38E4-44B7-8B30-2E58E0E59005.jpeg

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oss003
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Re: Atom duo 64k board issue

Postby oss003 » Tue Feb 06, 2018 7:35 pm

Yes, 32KB is enough for running all programs in the Acorn Atom Archive including the Retrosoft titles.
I must confess that I've never seen programs that use 2 banks of 32KB except Rolands Atom2015 of course ..... 8)
Have fun .....

Greetings
Kees

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IanS
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Re: Atom duo 64k board issue

Postby IanS » Tue Feb 06, 2018 7:46 pm

oss003 wrote:I think you typed #97FF instead of #9FFF in line 30, but that doesn't matter.

That wouldn't affect the printing of the last two blocks, I can't see an easy mistake that would cause the last two blocks to be untested.

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oss003
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Re: Atom duo 64k board issue

Postby oss003 » Tue Feb 06, 2018 7:51 pm

IanS wrote:That wouldn't affect the printing of the last two blocks, I can't see an easy mistake that would cause the last two blocks to be untested.

You're right, ooopppsss .... :oops:
Then there's probably a typing mistake in line 90/100 because that line should display ROM and I think the video RAM isn't piggypacked.

Greetings
Kees

Telemedic
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Re: Atom duo 64k board issue

Postby Telemedic » Fri Feb 09, 2018 2:19 am

Hi! I retyped the program, and I think I got it right this time!
Attachments
image.jpg


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