8 replies to this topic

[Lynxman]

Hello all,

i made 2 new Falcon memory boards.

The first board use PS/2 simm and the second board use chips.

The PS/2 board is cheaper, but you need to modify the shielding of the Falcon. The contacts of the PS/2 socket is made with gold contacts.
I have ordered only 20 PCBs of this board and there will be no additional. I have only 12 PS/2 sockets in stock, so i will sell some of them without it. (Or maybe i will find a source for it.)
For this board i can not give a guarantee that it will work with modified Falcons. Because my Falcon is running with 16MHz or 32MHz for the CPU but the system bus is 16MHz.
And it depend to the PS/2 simm if it will work with higher bus clock.
Used PS/2 simms: TI, Micron, Samsung, Hitachi

There is no need to modify the shielding with the other board. And there are no additional contact resistance between Memory and PS/2 socket and the lines to the memory chips are shorter.
This board is a modified version from my white 14MB Falcon memory board. This boards was tested with several Falcons in different configurations with speeders, bus clock mods etc.
I am sure the black board works on every Falcon. The tests with this board was always fine.
At the white board the chips was soldered to the top-side, at the black board the chips are soldered to the bottom side.
Used chips: Siemens, TI, Samsung, NEC

Both boards have a jumper to select 4 or 14MB. It is possible to connect to a switch. (switch not included)

All boards (of cause, the version without the PS/2 socket i can not check!) will be checked with my Falcon.

Price:

Black board with chips: 40 Euro
PS/2 board including PS/2 simm: 30 Euro
PS/2 board without PS/2 simm: 26 Euro
PS/2 board without PS/2 socket and without PS/2 simm: 22 Euro

For shipping etc. please send me a PM with our adress.

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[Lynxman]

Additional Information:

The chips i use for the black board are all with 60ns speed!

[amarok45]

Hello Lynxman!

At last I found someone who may provide me with a 14MB Falcon memory board.

Do you still have some of them?

Please, let me know the way of getting one.

Best regards

Yann SAVENYE

[Mark_G]

Why don't you place the simm holder for the PS/2 sim's at the underside of the board ?

Then, no shielding work must be done.

Mark

Edited by Mark_G, Tue Nov 1, 2011 2:12 PM.

[Lynxpro]

Is there any way to recover the lost 2MB that the Falcon won't address and use it as a RAM disk or something?

I can't remember what 14MB board is in my Falcon but it is a shame that 2MB is lost when installing the usual 16MB SIMMs.

I've seen other boards [like the CT63] that can go up to around 512MB but addressing that much RAM seems to require a CPU more powerful than the stock 68030... Just thought I'd ask this since this is a related thread and an active one at that...

[DarkLord]

Lynxpro, on Tue Jan 31, 2012 12:39 AM, said:

Is there any way to recover the lost 2MB that the Falcon won't address and use it as a RAM disk or something?

I can't remember what 14MB board is in my Falcon but it is a shame that 2MB is lost when installing the usual 16MB SIMMs.

I've seen other boards [like the CT63] that can go up to around 512MB but addressing that much RAM seems to require a CPU more powerful than the stock 68030... Just thought I'd ask this since this is a related thread and an active one at that...

AFAIK, that 2 megs is reserved by TOS for hardware. I'm not sure I'd want to mess with it.

Maybe someone with more knowledge can clarify this...

[rdemming]

The Falcon uses only 24 address lines (even while the 68LC030 has 32) limiting the memory range to 16MB. The top 2MB is reserved for ROM and memory mapped IO. This increases compatibility with older software (68000 based) since the 16MB address range is repeated in the 32bit logical address space just as with the 68000. Most software uses the faster word addressing mode (specifying only 16 bits of a 32 bits address) to access the IO range. Normally these word addressing modes addresses $00000000-$00007FFF and $FFFF8000-$FFFFFFFF but on an 68000 (with 24 address lines) the IO area $00FF8000-$00FFFFFF is automatically mirrored in the $FFFF8000-$FFFFFFFF area thus enabling the use of word addressing for the IO area.
On an Atari TT with full 32 bit address range, the IO range is mirrored in the $FFFF8000 area for backward compatibility by the TT's addressing logic.
So that is the reason why the upper 2MB is hidden and is not accessible.

However, it is possible to make this space available by a technique already used on Atari 8-bits named bank-switching. With an hardware modification you could for example redirect access to $00C00000-$00DFFFFF to the last 2MB of the memory. You could use for example the soundchips Port A bit 2 (officially the drive 1 select but there is no 2nd floppy driveon the Falcon) to switch the bank, controlling address bit 17 of the memory when bits 19-17 of the address bus are '110'. Things only get a little bit more complicated because drams use rows/columns addressing so there is not really an address bit 17 on the memory chips. Thus you need to translate address bit 17 of the memory to the proper combination of MADR & RAS/CAS signals.

Robert

[rdemming]

As an additional note, bankswitching like this only works correctly when the software has full control of the machine or when the OS is aware of the bankswithced memory. Normally other programs could be loaded and may reside in the bankswitched area. In that case the other program could be swapped out and crash if the software is switching banks.

Robert

[Lynxpro]

rdemming, on Tue Jan 31, 2012 5:11 AM, said:

The Falcon uses only 24 address lines (even while the 68LC030 has 32) limiting the memory range to 16MB. The top 2MB is reserved for ROM and memory mapped IO. This increases compatibility with older software (68000 based) since the 16MB address range is repeated in the 32bit logical address space just as with the 68000. Most software uses the faster word addressing mode (specifying only 16 bits of a 32 bits address) to access the IO range. Normally these word addressing modes addresses $00000000-$00007FFF and $FFFF8000-$FFFFFFFF but on an 68000 (with 24 address lines) the IO area $00FF8000-$00FFFFFF is automatically mirrored in the $FFFF8000-$FFFFFFFF area thus enabling the use of word addressing for the IO area.
On an Atari TT with full 32 bit address range, the IO range is mirrored in the $FFFF8000 area for backward compatibility by the TT's addressing logic.
So that is the reason why the upper 2MB is hidden and is not accessible.

However, it is possible to make this space available by a technique already used on Atari 8-bits named bank-switching. With an hardware modification you could for example redirect access to $00C00000-$00DFFFFF to the last 2MB of the memory. You could use for example the soundchips Port A bit 2 (officially the drive 1 select but there is no 2nd floppy driveon the Falcon) to switch the bank, controlling address bit 17 of the memory when bits 19-17 of the address bus are '110'. Things only get a little bit more complicated because drams use rows/columns addressing so there is not really an address bit 17 on the memory chips. Thus you need to translate address bit 17 of the memory to the proper combination of MADR & RAS/CAS signals.

Robert

What he said.


(Thanks!)