On 06/06/2012 01:18 PM, firstname.lastname@example.org wrote: > > On 2012-06-06, at 04:35, Jim Brain wrote: > >>> If it is enough to grab that one line (after Gerrit's e-mail I got >>> enlightened ;-) than I'd leave the original ROM where it is >>> (especially if not socketed) and tap only on the line either by >>> cutting a trace or unsocketing a pin from PLA. I believe it is better >>> to let also people with soldered-in ROMs do it without unnecessary >>> desoldering. Of course if someone has it socketed and wants to save >>> some milliamps - sure. But I would prefer not to _require_ removing >>> the chip. >> Not removing the IC means you need to "disable" it somehow. > > By redirecting _CS from it to the board? You can leave the trace between the PLA and the Char-ROM in place. The Char-ROM is a 2332 which has 2 _CS signals, one of them active HIGH in this case. All you need to disable the onboard Char-ROM is to cut the connection between pin 21 and pin 24 and then tie pin 21 to GND. On some board revisions this is easily done (250466 for example), on others cutting the trace between the PLA and the ROM might be easier. In that case you have to connect pin 20 to pin 24 using a pullup resistor (4.7 KOhm schould do) since open inputs are usually but not always considered HIGH. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2012-06-06 16:00:06
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