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by troed
Sun Mar 18, 2018 10:02 pm
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 135
Views: 36304

Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Where is reset in your code ? I added a simple AND term with RESET on one of the inputs. Since it's an input-only pin, I don't see how it can drive anything low ... (Actually there's an internal pullup so if I don't connect the wire the GAL logic acts as if RESET was high). /* inputs */ PIN 1 = clk...
by troed
Sun Mar 18, 2018 9:41 pm
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 135
Views: 36304

Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Did you try a 1k pull up and a larger cap on reset ? So I got a bit sidetracked by a friend giving me a 520ST last weekend. That model was my original Atari and I just had to piggy-back upgrade its RAM :D I've now added a 2.3 kOhm pullup to RESET, which means it's ~650 Ohm when measured in circuit....
by troed
Sun Mar 18, 2018 1:13 pm
Forum: DISPLAYS & CONVERTERS
Topic: Atari ST Display Basics
Replies: 31
Views: 17638

Re: Atari ST Display Basics

I just checked pin 8 on STE & STM is via 1.2K resistor. Assuming a typo Ingo ? It's "common knowledge" that there are somce machines that don't put out 12V ... but considering even the 520ST schematics has it I'm quite confused as to exactly which those machines would be. 12V / 10mA pin (STE) : On ...
by troed
Sun Mar 18, 2018 10:23 am
Forum: DISPLAYS & CONVERTERS
Topic: Atari ST Display Basics
Replies: 31
Views: 17638

Re: Atari ST Display Basics

[*] GND on ST, 12V on STE I don't think it's this easy. It's GND on 520ST (I have one here), but surely Ube's switches work on a lot of STs and not just STE and it requires 12V edit: So now I'm more confused than before. I just looked at the 520ST schematics and they clearly show pin 8 connected to...
by troed
Sun Mar 11, 2018 11:10 am
Forum: PSU (power supplies)
Topic: Atari Falcon PSU
Replies: 10
Views: 2347

Re: Atari Falcon PSU

It's the brown 400V I'm thinking about ... I usually see those on recaps ;) But yeah, the Q.C-sticker does look like something from Atari.
by troed
Sun Mar 11, 2018 11:00 am
Forum: PSU (power supplies)
Topic: Atari Falcon PSU
Replies: 10
Views: 2347

Re: Atari Falcon PSU

Looking at the type of caps on that PSU - are you certain that this PSU hasn't been recapped already by a previous owner?
by troed
Sat Mar 10, 2018 8:11 pm
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 135
Views: 36304

Re: Boosting STFM: 16MHz bus, 64MHz Shifter

So this RESET thing ... I've been working on it on and off throughout the day, but the results confuse me. If I measure RESET on the CPU with the LA, it's pretty much what I expect. I'm surprised at how it bounces high and low, but at least it stays high when the computer runs. If I now connect the ...
by troed
Sat Mar 10, 2018 7:48 am
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 135
Views: 36304

Re: Boosting STFM: 16MHz bus, 64MHz Shifter

(So yesterday before dozing off to sleep I seem to have ordered some 48MHz oscillators and GAL22V10 ... ;))

I do believe a DE duty cycle of XXXX..XXXX..XXXX..XXXX..XXXX for a 32MHz MMU and Shifter clocked at 48MHz would work.
by troed
Fri Mar 09, 2018 8:58 pm
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 135
Views: 36304

Re: Boosting STFM: 16MHz bus, 64MHz Shifter

Interesting! At some point I was running the shifter on its own 5V regulator (driven from the 12V line).. The shifter doesn't exactly get stable voltage, even if you add 4,700uF across it! So it may be worth trying a 5V regulator on the shifter ( break its 5V feed of course) and see if its really v...
by troed
Fri Mar 09, 2018 6:47 pm
Forum: TWEAKS & FIXES
Topic: Hissing and whistling in the STe audio output
Replies: 122
Views: 23163

Re: Hissing and whistling in the STe audio output

Paulo P wrote:
Fri Mar 09, 2018 6:40 pm
Here is a normalized sample from my STe audio output recorded directly by audio cable. So, what do you think? Thanks very much.
You have an enormous peak at 2600Hz, just as I do. Then you have one at 15.x kHz which is interference from the video output.

The 2600Hz peak is really interesting.

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