CPU swap?

[bfollowell]

Like Exxos suggested, I plan to swap the CPU in my STE for an MC68HC000EI20. It'll be newer and it's a lower power version, so it will lower the load on the PSU some. When I get my new STE modded and upgraded, I plan to sell off the old 1040STF and original 520ST that I have. I figured I may as well replace their processors with a lower power modern equivalent as well. The MC68HC000P8 seems to be a direct drop-in replacement for the MC68000. Has anyone here ever done this or have any idea why it wouldn't work?

Thanks.

[exxos]

A lot of STF machines will malfunction with a HC CPU. So if you go down that route, you will have to change the bus resistors and likely do some debugging. A HC CPU on the STE only just works, and the bus resistors should really be changed there also. Most of the time you can get away without doing it but not always.

[bfollowell]

OK, so adding a 10K bussed resistor array to the 1772 databus pins like in #3 of Mandatory Fixes and swapping out the bus resistors like in #12 of Mandatory Fixes? These two fixes would get the HC to work with the STE and possibly with the ST & STF?

[exxos]

OK, so adding a 10K bussed resistor array to the 1772 databus pins like in #3 of Mandatory Fixes and swapping out the bus resistors like in #12 of Mandatory Fixes? These two fixes would get the HC to work with the STE and possibly with the ST & STF?

You can try those things, but I really don't recommend changing any STF machine for a HC just for the sake of it. There are so many revisions of the boards with various faults , it can turn into a nightmare. Swapping resistors may not be enough. There is also long term testing needed. It may work fine without any changes at all one day, turn it on a week later and just a black screen. So I really don't suggest a HC in any ST/F/M machine. Its not going to reduce power consumption by any great amount.

If your wanting to go for lower power consumption then there are much better ways. Like swapping the RAM for one of my 4MB MMU kits will reduce power no end. Though in fact my PSU's are much more efficient than the original PSU's.

[bfollowell]

OK, I'll nix that idea then and just swap for an HC in my STE.

Mandatory Fixes #3 & #12 are still considered mandatory for an ST and STF though,right? They just won't necessarily help with an HC CPU.

[exxos]

OK, I'll nix that idea then and just swap for an HC in my STE.

Mandatory Fixes #3 & #12 are still considered mandatory for an ST and STF though,right? They just won't necessarily help with an HC CPU.

I quote in the fixes section fixes for the machines for various machines. so sections 1,3,4,11,12 are still mandatory for ST & STE machines. So any STE listed in the list are mandatory, any STF machines listed for a fix is mandatory. The STE has other fixes in addition such as 2,5,8.

[bfollowell]

OK, it was the F that seemed to be missing, but I guess it was because there were just so few fixes listed for it. I only see two listed specifically; 11 & 12, and then the couple listed for all machines.

Thanks Exxos. I'll get started on my fixes.