Search found 93 matches

by troed
Mon Oct 09, 2017 2:11 pm
Forum: FLOPPY DRIVES KITS & UPGRADES
Topic: How to get TOS to see the 1.44MB drives
Replies: 22
Views: 1112

Re: How to get TOS to see the 1.44MB drives

exxos wrote:
Mon Oct 09, 2017 1:02 pm
It is also possible that your 1772 may not actually work at 16 MHz... You're welcome to send it to me to testing if it helps..
This is my guess. Is it a VL-model? (That's what my Megas have)

/Troed
by troed
Sun Oct 08, 2017 4:31 pm
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 45
Views: 2747

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

Thanks, will look into dtack.

In the meantime, here are the clocks sampled at CPU, DMA and Floppy. I did a few runs with detection level at 1.0V up to 2.8V to try to figure out if maybe they were weak (still waiting for that scope).
la_cpu_dma_floppy.png
la_cpu_dma_floppy.png (303.92 KiB) Viewed 562 times
by troed
Sat Oct 07, 2017 12:38 pm
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 45
Views: 2747

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

A bit of shooting in the dark at the moment, but: 33R added to 8MHz (for GLUE, WD etc) - no change 10k pullup added to DMA databus - no change I can very repeatedly and predictably keep pressing ESC to get more or less correct data read from the disk. Very seldomly (but it happens) the size or filen...
by troed
Fri Oct 06, 2017 6:27 pm
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 45
Views: 2747

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

exxos wrote:
Fri Oct 06, 2017 5:15 pm
I would suggest you get a 74F161 as well.
Now ordered.

:)
by troed
Fri Oct 06, 2017 12:57 pm
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 45
Views: 2747

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

exxos wrote:
Fri Oct 06, 2017 12:45 pm
Add a 1K resistor (pull up) on CPU /DTACK and /AS see if that helps. Also add a sil array on the DMA databus.
Thanks for the suggestions :)

(Also, I just placed an order for a scope ... will arrive in ~three weeks)

/Troed
by troed
Fri Oct 06, 2017 11:08 am
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 45
Views: 2747

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

Pullups changed on address and data bus, no change. Tested with the freshly refurbished Epson 340, no change. However, since I did a bit more testing: The drive seems to have issues reading more than writing/formatting. Most often it will simply believe disks have 0 bytes used in 0 files, but someti...
by troed
Thu Oct 05, 2017 9:47 pm
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 45
Views: 2747

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

ah ok, thought you had a scope (my bad sorry!) I thought so too until I checked what was in the LA box I purchased a while ago today ;) I would make sure you have some 33R in series with clock inputs and outputs. The LA does not show the "real picture" a lot of the time. Signals could be glitching ...
by troed
Thu Oct 05, 2017 9:39 pm
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 45
Views: 2747

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

You also need to post scope images to see the ringing on the signals and adjust series resistors accordingly. Yeah apparently I need an oscilloscope extension for my LA and it's only available for the previous hw version :( Or something. I had really hoped not having to buy a separate oscilloscope ...
by troed
Thu Oct 05, 2017 7:45 pm
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 45
Views: 2747

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

Here's a capture of the 16MHz (from MMU), 8MHz (from MMU) and 4MHz (divided by the 74LS74 from the 8MHz) taken at the maximum speed of my LA. The relationship between the clocks is stable between captures at that speed. la_16_8_4_400mhz.png edit: Annotated. I'd say the 8MHz clock (MMU original 4MHz)...
by troed
Thu Oct 05, 2017 5:05 pm
Forum: MEMBER BLOGS
Topic: Boosting STFM: 16MHz bus, 64MHz Shifter
Replies: 45
Views: 2747

Boosting STFM: 16MHz bus, 64MHz Shifter

edit: A long prosaic writeup of all the steps can be found here: https://blog.troed.se/projects/atari-st-new-video-modes/ Since a few months back I've slowly been modifying one of my 1040 STFMs with the "Stefan Nitschke 16MHz mod". I got the inspiration from an Atari-Forum thread by exxos where he s...