@66 #561 BBC Micro DFS >> I've just purchased an old BBC Micro Model B OS 1.20. Unfortunately it >> does not have a DFS fitted. I have an old BBC which is broken. How do >> I transfer the DFS between the two machines? Do you mean DFS or do you really mean 'it has no disk interface'? The DFS is in one of the ROMs in the sockets in the South-East corner of the PCB, usually marked on the top with 'DFS' or 'DNFS'. Ok, I'm assuming you really mean that there's no disk interface: The disk interface in a BBC B is usually an 8271 one - the chips you need to cannibalise are as follows: IC78 8271 FDC IC79, 80 7438 (not 74LS38) IC82 74LS10 IC81, IC86 74LS393 IC83, IC84 CD4013B IC85 CD4020B IC87 74LS123 Fit the ICs into the sockets. On issues 1 or 2 PCBs, connect link 8 with a wire link. On issue 1, 2, or 3 PCBs, "cut the leg of IC27 pin 9 as close to the PCB as possible ans the track connected to it on the component side of the circuit board between IC27 and IC89, then reconnect the cut IC leg to the East pad of link S9 with a short length of insulated wire." On issue 4 onwards PCBs, cut link S9. Set the following jumpers: S18 - NORTH S19 - EAST S20 - NORTH S21 - 2xEAST/WEST S22 - NORTH S32 - WEST S33 - WEST The 8271 DFSs are DFS 0.90 (slow and buggy, Tube code crashes) and DFS 1.20 (much faster, most bugs fixed, Tube works, NFS3.60 also in rom). If the B has a 1770 upgrade, it will be on a daughter board plugged into the 8271 socket. Mail me if you need these instructions. PS: I have copies of the BBC Micro B/B+ Service Manual (which includes the above information in more detail) available for sale for `12 (inc. UK P&P).