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I didn't find this in the archives. This is the original supplementary manual shipped with the Dragon 64, describing the additional features over the D32.

-- Rolf

I'm sorry that I cannot help here. The schematics and the address ranges in the pictures indicate that this is two 8k PROMs in a 24 pin package. I am unable to find any EPROMs that are compatible with those specs. AllDatasheet (http://www.alldatasheet.com/) is a good place to start if you want to di...

I have checked the diagrams and photos again, and it looks like I was terribly wrong regarding the D32 PROMs. These PROMs are 8k large but come in a 24 pin package. I am unable to find an EPROM that meets those specs. It is probably still pretty easy to replace the D32 PROMs with standard EPROMs by ...

No, unfortunately they are of no help. All pictures with good enough resolution shows ROMs marked with "Dragon Data" and no part numbers. I'll take another shot at decoding the diagrams tomorrow...

I've given the schematics a try, but it is really hard to read the part numbers and pin numbers. However, it looks like the D32 contains two PROMs both with 13 address lines. That means two 8k PROMS, giving a total of 16k. Given my problem with reading all the pin numbers, I can't be completely sure...

Don't know what the purpose of the board is but both additional ICs are quite standard logic gates. SN74LS74 is a pair of D-type flip-flops (basically 1 bit memories) and SN74LS32 contains four 2-input OR gates. My guess would be a "patch" to compensate for an error on the main motherboard, but that...

The Dragon 64 uses two 16k PROMs. These PROMs are compatible with the 27128 family of EPROMS. You can get these EPROMS from Maplin (http://www.maplin.co.uk) or ELFA (http://www.elfa.se) or similar. Some vendors don't seem to carry the 27128 anymore, but a pair of 27256 (32k) EPROMS can also be used....

I did a similar trick back in the good old days. I simply removed LM1889 from its socket. This disabled color, but also resulted in a much steadier monochrome display. I did it on both my D32 and D64 with good results. LM1889 has been socketed (not soldered) on all Dragon models that I have seen so ...

I'm also back after having re-created my account. Why where the accounts closed? I'd be surprised (in a positive way) if the community is so large that there is a need to purge the user database of inactive users...

-- Rolf