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Kiss68030 Updates [message #10632]

Thu, 14 March 2024 06:33

denis2342
Messages: 23
Registered: February 2017

Junior Member

Hello

Some news on the KISS 68030 CPU Board front:

I made a new v6.8 Linux Kernel with builtin support for the USBFIFO from will. It will appear as /dev/ttyUF0
(USBFIFO needs to be on address 0xFFFF000C and irq set to IR1).

It was build with the changes from this post: https://www.retrobrewcomputers.org/forum/index.php?t=msg& ;th=780&start=0&
but with newer kernel source and the usbfifo module as addition from me.

On the hardware itself I changed U303 from a 74LS14 to a 74ALS04. This Logic IC controls the reset line to the CPU.
But at a cold start the CPU begins to come to life at about 2.4V and this 74LS14 is still sleeping, when it then wakes
up and resets the CPU (because normally the CPU should be cold started with the RESET pin active) the CPU
seems to stall. This can be changed with a 74ALS14 which is a little faster, even better would a 74AHCT14 or best
would be a 74AHC14 (starts operating at 2V) but for that the 74F164 ICs need to be changed to CMOS (best would be 74AHCT164).

With this change I can run at 36.096Mhz reliably for days. A 74AHC14 is on the way to me and I will test 40MHz soon.

Now to the MF-PIC board:

the way to less waitstates is to speed up the signals to the NS32202. the CS signal (chip select) is too slow
for 2 wait states. one way to speed it up is to change the 74LS139 in U13 to a 74AHCT139 or at least
a 74ALS139. Also all other ICs on that board can be changed to faster ALS versions (or AHCT).
(the 74LS688 would be a very good candidate, but the ALS version of it are hard to get now).

btw, the 688 could be replaced by a GAL as a drop in replacement.

With these changes I can run my board with 33MHz and 2 WS for the IO boards.

Denis

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		Kiss68030 Updates By: denis2342 on Thu, 14 March 2024 06:33
		Re: Kiss68030 Updates By: coredump on Thu, 26 December 2024 17:35

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