H5 A3 & B1 pullup resistor change

Information and progress towards the H5 board.
User avatar
DoG
Posts: 1125
Joined: Sat Apr 07, 2018 12:26 pm

Re: H5 A3 & B1 pullup resistor change

Post by DoG »

stephen_usher wrote: Mon Jul 19, 2021 3:30 pm It doesn't seem to be able to drive the bus as strongly as the 68000 and 2.2K is technically way below the recommended minimum resistance for TTL pull-up resistors (to prevent over current on the outputs), which is 10K. On my ST with the TF536 4.7K gave intermittent floppy (Gotek) access (corruption) and 10K pull-ups allowed it to work fully. 2.2K pull-ups stopped things working at all.
To be clear, I have only read from floppy so far, didn't write anything yet so maybe I have to change them again.

On my Mega I run 4.7K on address bus and 3.3K on databus according to the PAK/3-030 manual. I also ran TF536 on it. But I haven't ran it that much to be honest. But on WD1772/DMA side I have 10K pull-up.
Post Reply

Return to “H5 Phoenix Platform Edition”