On 04/25/2012 09:37 PM, didier@aida.org wrote: > > any idea of use on the jumpers on: > http://www.netfilters.eu/plus4/IMAG0092.jpg The jumpers look like they will do the same thing as the jumpers on the Plus/4 board. You can use them to change the layout of the socket to accomodate a 2364 ROM (the 24pin ones used in the old C64 and 1541). Since it's unlikely anyone wants to do that, you can leave them out if you do your own board and just hardwire it. Anyone wanting to use a 2764 can do that with the jumpers set for the mask ROMs currently in there. > any idea of the size of the roms ? The ROMs are 16KB (23128). They can be replaced by 27128 EPROMs (or 27256 with the data in the upper half) if one little detail is fixed. The 27128 expects Vpp on pin 1 and, in normal operation would like to see Vcc (+5V) there. The ROM sockets on the C16 and C116 PCB take this in account and have pin 1 connected to +5V. The ROM sockets in the Plus/4 do not (all 4 of them) and it look like the cartridge you photographed doesn't either. Usually the EPROMs work anyway, but it's not according to spec. So if you do your own layout, it would be a good idea if you'd connect Pin 1 of each ROM socket to +5V on your board. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2012-04-26 16:00:05
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