Investigating variances on motherboards.

Help & information about the STE V1 series boosters.
Post Reply
User avatar
exxos
Site Admin
Site Admin
Posts: 23498
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Investigating variances on motherboards.

Post by exxos »

I thought I would post this information in the booster section as it will likely get lost in my blog post otherwise..

https://www.exxosforum.co.uk/forum/viewt ... 270#p41224
I've been experimenting with the STE booster code again. Basically bypassing the 8mhz signal as its so far seems to be causing various odd issues. So the 32mhz gets down clocked to 8mhz and that is used instead.

Anyway, the booster is now using a 8mhz gal generated clock.the tests in GB6 have changed slightly. Integer division has gone up from 355% to 364%, and some other tests have dropped a few percent. Its probably to be expected as there would be a slight phase shift in the 8mhz clock so it would explain the slight differences in the scores.
Mods are listed here also
https://www.exxosforum.co.uk/forum/viewt ... 514#p41514

However, I have now found that there might be a wakeup state on the STE as sometimes the results for int-div are 355% like normal, other times its 364%. Seems to be random between totally powering off and powering back up again. I would assume it to be that the system 8MHz clock varies in timings between the GAL generated 8MHz generated from the 32MHz clock.

I am not going to investigate this any further ( I just do not have time) . But I thought I would mention this for future reference if people get slight variations in benchmark figures between power ups.

Also note that this "issue" does not affect any currently produced boosters as none of them use the GAL generated 8MHz clock yet.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
User avatar
PhilC
Moderator
Moderator
Posts: 6016
Joined: Fri Mar 23, 2018 8:22 pm

Re: Investigating variances on motherboards.

Post by PhilC »

A thought, some boards have a 4 pon oscillator and other pins have a 2 pin crystal.

Could it be a difference in the two circuits?
If it ain't broke, test it to Destruction.
User avatar
exxos
Site Admin
Site Admin
Posts: 23498
Joined: Wed Aug 16, 2017 11:19 pm
Location: UK
Contact:

Re: Investigating variances on motherboards.

Post by exxos »

PhilC wrote: Tue Jun 16, 2020 6:12 pm A thought, some boards have a 4 pon oscillator and other pins have a 2 pin crystal.

Could it be a difference in the two circuits?
I don't think so. Its the combo generating the 8MHz clock which is the issue. Its a lot weaker on integrated blitter machines and a lot noisier on external blitter machines. The combo would be the reason for the clock skew between 8MHz and 32MHz.
https://www.exxosforum.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxosforum.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
viewtopic.php?f=17&t=1585 Have you done the Mandatory Fixes ?
Just because a lot of people agree on something, doesn't make it a fact. ~exxos ~
People should find solutions to problems, not find problems with solutions.
Post Reply

Return to “STE V1 SERIES 32MHz BOOSTER”