Yes, if its likely to work that is...
DMA port "update" ideas..
- exxos
- Site Admin
- Posts: 13326
- Joined: Wed Aug 16, 2017 11:19 pm
- Location: UK
- YouTube: https://www.youtube.com/user/exxosuk
- Contact:
Re: DMA port "update" ideas..
https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
- exxos
- Site Admin
- Posts: 13326
- Joined: Wed Aug 16, 2017 11:19 pm
- Location: UK
- YouTube: https://www.youtube.com/user/exxosuk
- Contact:
Re: DMA port "update" ideas..
I don't, I'm quite insane you know




https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
- Icky
- Moderator
- Posts: 2722
- Joined: Sun Sep 03, 2017 10:57 am
- Location: UK
- YouTube: https://tinyurl.com/yals4a3k
- Contact:
Re: DMA port "update" ideas..
16MHz works on DMA and can see floppy with the new WD1772 buffer board. Reading, writing and formatting all work.
However as before if I plug in Gigafile as well it doesn't see HDD or Floppy.
However as before if I plug in Gigafile as well it doesn't see HDD or Floppy.
- exxos
- Site Admin
- Posts: 13326
- Joined: Wed Aug 16, 2017 11:19 pm
- Location: UK
- YouTube: https://www.youtube.com/user/exxosuk
- Contact:
Re: DMA port "update" ideas..
Odd. Good that the floppy works.. Could be the DMA thinks gigafile is ready when its not. Could just be a timing issue in GF.. Not sure why floppy not working with GF, sounds like maybe data conflict .
What I may do is loan you my ultasastan to try out after Xmas.
There is another thought that we could run the DMA at stock speed while its getting data from a device but double clock it when its copying to ram. On a stock machine its not going to show any speed boost as ram isn't running any faster.
In any case. It does hint like the DMA is OK running at double speed if you can format a floppy OK and read from it OK..
What I may do is loan you my ultasastan to try out after Xmas.
There is another thought that we could run the DMA at stock speed while its getting data from a device but double clock it when its copying to ram. On a stock machine its not going to show any speed boost as ram isn't running any faster.
In any case. It does hint like the DMA is OK running at double speed if you can format a floppy OK and read from it OK..
https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
Re: DMA port "update" ideas..
I'm not sure that running the DMA at 16MHz will accelerate any transfer as the GLUE/MMU are the one generating the memory address for the transfer and not the DMA itself (it only has A1 from the address bus). So running it at 16 MHz would only affect the signals generated by the DMA and it might end up out of sync with what the GLUE/MMU are doing doing.
Working ones : MegaSTE (68020) / TT030 / Falcon with AB040 & Eclipse / 1040STF
Need testing : Falcon with CT2
Need testing : Falcon with CT2
Re: DMA port "update" ideas..
Right. These DMA cycles (as opposed to the ones generated by Blitter) are a coordinated effort among the 3 chips. The only thing that DMA does is to pulse the RDY signal. GLUE is the bus master and asserts all the bus control signals at its own pace. The addressing is generated internally by MMU.rpineau wrote: ↑Sat Dec 22, 2018 6:03 pmI'm not sure that running the DMA at 16MHz will accelerate any transfer as the GLUE/MMU are the one generating the memory address for the transfer and not the DMA itself (it only has A1 from the address bus). So running it at 16 MHz would only affect the signals generated by the DMA and it might end up out of sync with what the GLUE/MMU are doing doing.
It's interesting and even surprising that it works at all at 16 MHz. But not so much surprising when you consider that the interface with DMA is not fully synchronous. The exact behavior might depend on the specific version of the chipset, GLUE and DMA.
http://github.com/ijor/fx68k 68000 cycle exact FPGA core
FX CAST Cycle Accurate Atari ST core
http://pasti.fxatari.com
FX CAST Cycle Accurate Atari ST core
http://pasti.fxatari.com
Re: DMA port "update" ideas..
Yes, I think that the fact it works is mostly because of the GLUE/MMU timing not being changed.
Working ones : MegaSTE (68020) / TT030 / Falcon with AB040 & Eclipse / 1040STF
Need testing : Falcon with CT2
Need testing : Falcon with CT2
- Icky
- Moderator
- Posts: 2722
- Joined: Sun Sep 03, 2017 10:57 am
- Location: UK
- YouTube: https://tinyurl.com/yals4a3k
- Contact:
Re: DMA port "update" ideas..
Well I did not get as far as my STE but was in the process of sorting out my STFM DEV Motherboard to allow easier access to some of the chips.
Today I socketed the 1772 so thought I would try out the 1772 Buffer Board from the STF Remake.
All running well and functioning correctly. I placed a Gotek along side to show that the board fits nicely with it and doesn't restrict the cables.
- exxos
- Site Admin
- Posts: 13326
- Joined: Wed Aug 16, 2017 11:19 pm
- Location: UK
- YouTube: https://www.youtube.com/user/exxosuk
- Contact:
Re: DMA port "update" ideas..

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
- exxos
- Site Admin
- Posts: 13326
- Joined: Wed Aug 16, 2017 11:19 pm
- Location: UK
- YouTube: https://www.youtube.com/user/exxosuk
- Contact:
Re: DMA port "update" ideas..
I don't

https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.