Page 5 of 13

Re: DMA port "update" ideas..

Posted: Mon Oct 22, 2018 7:33 pm
by PaulJ
troed wrote:
Sun Oct 21, 2018 8:24 am
I've used the Mega ST internal ACSI format (added it to my main STE) to connect an internal Unicorn. I haven't really looked into the differences between the Mega STE internal ACSI and the Mega ST one, but quite a few existing stuff are compatible with the Mega ST.
Never realized it even though I've looked right at the pins. I have the mega 4 open sitting right from pulling the BLITTER. Yup learn something every day.
IMG_7690.JPG
IMG_7690.JPG (2.24 MiB) Viewed 786 times

Re: DMA port "update" ideas..

Posted: Mon Oct 22, 2018 8:16 pm
by exxos
Just thinking out loud again, but if UltraSatan is possible to fit internally, Would we even need the DB19 connector at all ?

Re: DMA port "update" ideas..

Posted: Mon Oct 22, 2018 8:45 pm
by PhilC
exxos wrote:
Mon Oct 22, 2018 8:16 pm
Just thinking out loud again, but if UltraSatan is possible to fit internally, Would we even need the DB19 connector at all ?
Not unless you want to maintain that backwards compatibility you were talking about. Personally I'd get rid and use something more accessible these days, like 25 pin din etc.

Be cool to have a coupe of internal DMA ports as well as the other expansions if possible.

Re: DMA port "update" ideas..

Posted: Mon Oct 22, 2018 8:59 pm
by exxos
Yeah probably should keep the port as the project goal is to remain total backwards compatibility..

My assumption would be that everyone would buy the internal hard drive, but of course if people already have external drives, they are not going to like been forced to buy an internal one this motherboard..

Re: DMA port "update" ideas..

Posted: Mon Oct 22, 2018 10:08 pm
by alienkidmj12
not sure how acsi works, but wont it allow internal and external at once, like scsi ? i remember back in the day you could use pass through cables and connect many devices ? or maybe im mistaken, the external boxes i had did contain acsi to scsi host interfaces.

Re: DMA port "update" ideas..

Posted: Mon Oct 22, 2018 11:16 pm
by Icky
Icky wrote:
Sun Oct 21, 2018 11:53 pm
exxos wrote:
Sun Oct 21, 2018 10:49 pm


IMP - pure evil DMA...

I guess its possible the drive could run a bit faster.. but its bottlenecked by ST-RAM anyway... I mean peters special drive can run twice as fast as ultrasatan with special hardware and software, so the DMA transfer is capable of double speeds.. So 16MHz DMA could work.. if Ultrasatan can keep up :twisted:
I'll give it a go tomorrow night - just been checking at what speed Gigafile can run at.

Its supposed have max transfer rates at 1800Kbps read and 1200Kbps write and an using it with an original Atari ST is supposed to be 1200Kbps read and 1000Kbps write.

So I should be able to detect improvement if it works.
Only just got to trying this out.

Clocking DMA to 16MHz the board did not function. Just got white screen and nothing else.

Need to look at what is going on but not sure if I will have much more time tonight.

Re: DMA port "update" ideas..

Posted: Mon Oct 22, 2018 11:27 pm
by exxos
alienkidmj12 wrote:
Mon Oct 22, 2018 10:08 pm
not sure how acsi works, but wont it allow internal and external at once, like scsi ? i remember back in the day you could use pass through cables and connect many devices ? or maybe im mistaken, the external boxes i had did contain acsi to scsi host interfaces.
Not really sure.. I know SCSI drives have select lines and they have been used on the ST.. I assume ACSI can do it as well..

Re: DMA port "update" ideas..

Posted: Mon Oct 22, 2018 11:28 pm
by exxos
Icky wrote:
Mon Oct 22, 2018 11:16 pm
Only just got to trying this out.

Clocking DMA to 16MHz the board did not function. Just got white screen and nothing else.

Need to look at what is going on but not sure if I will have much more time tonight.
Dam DMA! OH well, was worth a try :)

Re: DMA port "update" ideas..

Posted: Mon Oct 22, 2018 11:34 pm
by Icky
exxos wrote:
Mon Oct 22, 2018 11:28 pm
Icky wrote:
Mon Oct 22, 2018 11:16 pm
Only just got to trying this out.

Clocking DMA to 16MHz the board did not function. Just got white screen and nothing else.

Need to look at what is going on but not sure if I will have much more time tonight.
Dam DMA! OH well, was worth a try :)
Nope its booted - The 16MHz needed to be buffered so I took it from the 16MHZ_BUFFERED_1 that was spare on IC900 pin 12

Re: DMA port "update" ideas..

Posted: Mon Oct 22, 2018 11:40 pm
by exxos
Icky wrote:
Mon Oct 22, 2018 11:34 pm
Nope its booted - The 16MHz needed to be buffered so I took it from the 16MHZ_BUFFERED_1 that was spare on IC900 pin 12
oh sweet! benchmark time then ;)