Clock speed switch on Milan

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PeterS
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Clock speed switch on Milan

Postby PeterS » Sat Sep 22, 2018 1:47 pm

Inside the Milan there are jumpers to set the clock speed. Mine is set to 25MHz. I don't use 30MHz because of the scsi scanner.

It would nice to be able to quickly switch to 30 when I'm not using the scanner.

Could a switch be added so that it can be easily changed before booting ?

For 25MHz, jumpers 1 and 2 are bridged.
For 30MHz, jumpers 1 and 3 are bridged.

My questions are:

What sort of switch to use ?

If the cable runs to the case, will it work with the extra cable lenght ?

PeterS
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Re: Clock speed switch on Milan

Postby PeterS » Sat Sep 22, 2018 2:19 pm

I had a look in my junk box and found a DPDT slide switch that might fit in the spare D Connector slot in the case.

It will need about 8-10 inches of wire to reach the jumpers. Would this be too long ?

PeterS
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Re: Clock speed switch on Milan

Postby PeterS » Sat Sep 22, 2018 6:32 pm

I plan to use a 6-pin IDC plug and ribbon cable a bit like this http://www.hobbytronics.co.uk/idc-ribbon-cable-12

What I might do is leave the jumper on pin 1 and put the cable on pins 2 and 3

One switch position will connect pins 2 and the other will connect pins 3.

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frank.lukas
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Re: Clock speed switch on Milan

Postby frank.lukas » Sat Sep 22, 2018 6:38 pm

20% more speed ...

That is nothing. 060 upgrade brings more speed ...
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Re: Clock speed switch on Milan

Postby Rustynutt » Sat Sep 22, 2018 8:18 pm

frank.lukas wrote:20% more speed ...

That is nothing. 060 upgrade brings more speed ...


Purchased Amiga 040 to 060 adapter tested and built by seller. The schematic is same as Milan adapter. Soon will test (soon being relative in Atari world).

PeterS
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Re: Clock speed switch on Milan

Postby PeterS » Sun Sep 23, 2018 11:01 am

frank.lukas wrote:20% more speed ...

That is nothing. 060 upgrade brings more speed ...


I all ready have the 68060. Had it for longer than I can remember.

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Re: Clock speed switch on Milan

Postby PeterS » Sun Sep 30, 2018 9:39 am

I got the 12" ribbon cable, fitted it and jumpered the ends to see how the Milan reacted. It worked so I added a bit of Vero board, some dodgy soldering and a dpdt switch.

Now I can set it to 30/60 MHz most of the time and easily switch to 25/50 before booting to do scanning.

Now I just need to bolt the switch into the case.

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Re: Clock speed switch on Milan

Postby PeterS » Sat Oct 06, 2018 2:57 pm

Is anyone running their Milan at 33MHz ?

I think I tried it many years ago but it didn't work, can't remember thedetails.

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Re: Clock speed switch on Milan

Postby Rustynutt » Sat Oct 06, 2018 6:32 pm

Not yet, but the machine hasn't been released that long ago :)
Wasn't there a detail explaining need to change out an SN 74 IC to a faster time capable IC?
That is where I left off. Have an 060 adapter now, think first updating some IC, IKB fuze, ect best before plugging in the 060

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Re: Clock speed switch on Milan

Postby PeterS » Sun Oct 07, 2018 10:17 am

I think the suggestion was to replace an ic with the faster 74FTC157 version. If you can find one.

Rustynutt
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Re: Clock speed switch on Milan

Postby Rustynutt » Sun Oct 07, 2018 7:55 pm

Came back to edit, your experiment with clock switch reminded me of "Turbo Switch" on 386/486 boards. Those were long leads, but do not remember if they carried a clock, or provided some switch via an IC, like ACIA on Falcon with Nemesis and Power-Up.

Yes, the package size seemed to be hard to locate, admittedly not tried. I do have the DIP, AIRC the PCB location of the IC is tight.

Some years passed since last booting thee Milan.
To Do
Have several ATI PCI cards to use, JoEven provided driver.

Discover why SCSI does not work. Even with slow bus, and Michaels SCSI soft, media and scanners have big problems. It "resembles" improper termination looking at boot info. Attached hardware is correct.

Fuze keyboard and mouse vcc :)

Test super SCSI floppy with Milan. On Falcon, HD drivers sees and configures device, read/write fails.

Have anyone tested "dos emulation" such as PC Ditto with Milan? Still have love for CADKEY DOS version. :)

PeterS
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Re: Clock speed switch on Milan

Postby PeterS » Tue Oct 09, 2018 12:07 pm

I did try PC Ditto [edit: it was SoftPC not PC Ditto] about 20 years ago but never got it working.

Someone did release another PC emulator a couple of years ago. It worked but the key mapping was wrong so I had no idea what I was typing.
Last edited by PeterS on Wed Oct 10, 2018 12:19 pm, edited 1 time in total.

PeterS
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Re: Clock speed switch on Milan

Postby PeterS » Tue Oct 09, 2018 3:47 pm

There is one odd thing about the "turbo" switch, I had to restart after about an hour and the boot said 58MHz.

When I rebooted from cold the following day it was back to 60MHz but again once warm it said 58MHz.

I wonder if the the extra cable length is causing clock frequency drift or highlighting it ?

Rustynutt
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Re: Clock speed switch on Milan

Postby Rustynutt » Tue Oct 09, 2018 4:47 pm

I was watching CENT BENCH on stock Falcon test. It reads CPU drift from 14 to 16mhz at idle..?

This is where dml (Doug Little) explains the best :)


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