Richard Cini
2014-01-25 01:16:24 UTC
All â¹
I¹m reviving an old design for a 6502 SBC that was based on Daryl Rictor¹s
SBC. My version has some interesting things, including a
Commodore-compatable serial interface.
Anyway, I¹m adapting the old design to the new WDC chips in PLCC format and
I have a question about pull-ups on the *SO, RDY, and BE pins. In the
design, RDY, IRQ, NMI and RES are pulled-up to Vcc through a 3.3k rpack, but
the others weren¹t. I¹ve seen conflicting things, including the right value
for the resistors for these pins plus *IRQ and *NMI.
So, I¹m looking for some advice on how to treat these pins properly. The
6502/6809 board uses 1k but not on all of those pins.
Thanks in advance!
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.classiccmp.org/cini
http://www.classiccmp.org/altair32
I¹m reviving an old design for a 6502 SBC that was based on Daryl Rictor¹s
SBC. My version has some interesting things, including a
Commodore-compatable serial interface.
Anyway, I¹m adapting the old design to the new WDC chips in PLCC format and
I have a question about pull-ups on the *SO, RDY, and BE pins. In the
design, RDY, IRQ, NMI and RES are pulled-up to Vcc through a 3.3k rpack, but
the others weren¹t. I¹ve seen conflicting things, including the right value
for the resistors for these pins plus *IRQ and *NMI.
So, I¹m looking for some advice on how to treat these pins properly. The
6502/6809 board uses 1k but not on all of those pins.
Thanks in advance!
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.classiccmp.org/cini
http://www.classiccmp.org/altair32
--
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