Atom Disk rom paging ?

emulators, hardware and classic software for atom + system machines
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Atom Disk rom paging ?

Post by Prime » Sat Jun 11, 2011 9:36 pm

Hi all,

I'm currently doing some changes to the Atom driver in MESS, and have come across something I need clarification on.

The current driver has spaces for 16 4K roms banked in at #A000-#AFFF, which which are selected by writing the bank number to #BFFF, this is also supported by my RAM-ROM board.

However the driver is also coded with two #E000-#EFFF roms (as well as automatically using the DOS rom) though there is no code to page this rom in or out. Was there ever any hardware that allowed this, and if so how widely was it available ?

I'm also tempted to remove the DOS rom auto load from the driver as the DOS was an addon board, and should always be optional, and there is currently no way of disabling it.



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Re: Atom Disk rom paging ?

Post by oss003 » Sun Jun 12, 2011 11:34 am

Hi Phill,

as far as I know, there were no original released DOS add-on boards or DOS-roms for the Acorn Atom by Acorn.

An upgrated DOS-ROM was released by Teac. This was a copy of the original DOS-ROM with in free space the *OPT command (like the BBC).

The Dutch User Group did however release GDOS, a replacement for the Atom-DOS controller based upon a WD1793/WD1797. To use this board you needed GDOS, an updated DOS-rom at #Exxx.

Also a ROM board was released for switching 8 roms and 2 banks (4KB) at #Axxx or #Exxx for developments and testing.

Remind that in the DOS-rom there is software to control the original Acorn videoboard.


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