Jim Brain wrote: > On 2/4/2010 12:52 PM, Nate Lawson wrote: >> Rainer Buchty wrote: >> >>> On Wed, 3 Feb 2010, firstname.lastname@example.org wrote: >>> >>>> - The PDF says: "I/Os are not 5V tolerant". I see a lot of resistors >>>> to handle this. But is it still capable of driving the C64 plus some >>>> extras? If not, what is needed to make it capable? For example, will >>>> 74HCT245's and 541's do? >>>> >>> You don't need extra level shifters as GODIL comes readily equipped with >>> such. These you can use (adds 700ps to the timing path), but you don't >>> need to in case you don't require 5V tolerance. >>> >> Right, and you can configure the board for either the level shifter or >> series resistors. >> > How do you do the selection? I can see turning off the level shifters > by deselecting the 16211 bus transceivers, but how do you turn on series > resistors? Are they just always populated in parallel with the bus > drivers? > > I ask because I am working on a C64/128 expansion port (think CMD EX3 or > FB-EX3, etc.). I've been asked to put some bus drivers on the board to > clean up the C64 bus. SOme other designs are using '541s and 245s, but > those have way too long of latency. The 16211 looked interesting > because it only has a tiny < 1ns latency, but I would prefer a way to > deselect it if someone finds carts that do not like it. See page 30 of this pdf: http://www.oho-elektronik.de/pics/UM_GODIL.pdf R17 Vin--/\/\/-. | R18 PIN40------o----/\/\/-----o--F02 (on FPGA) | | |--|LVLSHIFT|--| R17 is populated, R18 is not. According to page 16, you have to solder bypass resistors (R18 in this case). It is not software-configurable. You have to decide on direct IO with pullups or level shifter at assembly time. I suppose you could provide jumpers or DIP switches also. -- Nate Message was sent through the cbm-hackers mailing listReceived on 2010-02-05 07:00:03
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