Another set of Ram / Rombox / Colour boards
credits Phill Harvey-Smith (stardot.org.uk)

Below you'll see a number of recently found extension I found on the internet for the Acorn Atom. As in the past, within the Atom community in the Netherlands and Belgium, still people are replacing the 2114 IC's ("radiator chips") by state of the art (large scale) components. Meantime the memory page #Axxx became better used.

Atom memory upgrades.

This adds 32K of ram maxing out the bottom half of the memory map, plus a rombox (in the flash rom), holding up to 16 4K extension roms, and optionially also holding the system rom.< /br> The jumpers allow the mapping out of the $0A00 block for campatibility with the disk interface, the mapping of the to 4K of ram as either rom box bank 0 or as the top 4K of normal ram (at $7000), and the enabling or disabling of the dos rom withing the flash rom. These can also be over-ridden by writing to location $BFFE. < /br> Left is the bare board, center is the assembled board, and right is the prototype for comparison.

Ram board in atom

This is how the board fits in the Atom, as you can see I have removed all the base ram 2114s, pluse the two system roms. This really helps as the 32K RAM chip, flash and CPLD will use much less power than the 2114s.....

One shot from another angle and with 8 KB video RAM board

Atom prototype colour board

Ok this is one of the things I'm working on at the moment, a modern replacement for the Atom Colour card, which unlike the Acorn original uses just 2 chips and a bunch of descretes, the main chip being the LMH1251 (mounted on the carrier board). As this is a 24 pin TSSOP, the final board should be quite small, though it is a little fidly to solder< /br> Also note that unlike the Acorn card (and incidentally the Dragon 32 / 64), no attempt is made to alter the frame sync to 50Hz, but I figure that this is less of a problem these days, as most monitors / TVs can cope with this. Also this is RGB only, as adding colour composite video would make the circuit much more complex, and RGB is better quality in any case

Atom colour board and video ram board

Ok the board on the left is the first attempt at the colour board (note I only finished assembling it last night I have not yet had time to test it !).
On the right is a replacement video ram board, this replaces the 12 power hungry 2114s with a single less power hungry 6264 The three wires you can see from this board don't plug into the video board but plug into the 74LS138 socket, which is under the video baord.

Atom colour board with video ram

Version 2 of the Atom color board with integrated video RAM