On 12/17/2013 10:26 PM, email@example.com wrote: > > On 2013-12-17, at 22:02, Gerrit Heitsch <firstname.lastname@example.org> wrote: > >> Another detail I'd take a closer look at would be the 7406/pullup combo that tristates the output the 74LS257 multiplexers when it's VIC's turn. Replace it with a real driver (74LS04). >>> >>> That “nice” 180 on the OC output. Right - another interesting idea. It was probably a good (read: cheaper) solution and a good use for the otherwise unused 7406 gate. >> >> Yes, and on the older boards R31 was 1KOhm and it still worked. > > Maybe less “usually” then ;-) The switch from 1 KOhm to 180 Ohm happened on the 250407 board. I have some with R31 = 1 KOhm und some with R31 = 180 Ohm. Not sure what was changed to make that necessary. But all the boards work and pass all the tests I try. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2013-12-17 22:03:51
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