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Author Topic: 6Mhz and more... (Read 45664 times)

Offline ron

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Re: 6Mhz and more...
« Reply #225 on: 2018.November.03. 21:54:09 »
Dear folks !

Today, with the inestimable help of GFlorez, we have made the modification to have a Z80 running at 4 and 10 MHz.
Thanks to the ZoZo's tutorial we have managed to make it work successfully.

In this video you can see part of the process and the RetroParla event that took place today, in the first part we did everything we could and later we continued in my workshop, until I finished and left everything running.It is amazing to see the Enterprise running at 10 MHz, thank you very much for all the information from EnterpriseForever.

This was the gone ! , cheers !

https://www.youtube.com/watch?v=f2gziI9P9_c

Offline Zozosoft

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Re: 6Mhz and more...
« Reply #226 on: 2018.November.04. 13:54:47 »
Nice work! :smt038

Online Z80System

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Re: 6Mhz and more...
« Reply #227 on: 2018.November.04. 14:03:15 »
It is much more easy to give the EP to Zozosoft ... :)

But coongratulations !
Z80 System

Offline pear

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Re: 6Mhz and more...
« Reply #228 on: 2019.March.14. 06:24:34 »
If someone would ask what is happening with the turbo card ...

In the winter there was a total downtime in electronic projects.
In the garage too cold, but the situation is slowly beginning to improve.

The first card was assembled in the full version with its own stabilizer that draws energy directly from the 9V power supply line.
Unfortunately, it is very difficult to test software because it requires a dual power supply when there outside the computer.
Memory emulators and programmators have their own + 5V power supply, which causes continuous problems with power supply starting  synchronization.
That's why I have to assembly another card in the version powered only with + 5V (it is possible only in the garage).

The only thing I managed to do during the winter season is the initial design of the adapter that can be connected instead of the LCD display and display the image directly on the monitor using the EXTC inputs. Such OSD.
Unfortunately, two PCBs together will not fit in the housing.
I would have to redesign the whole card board and design the OSD permanently on one PCB.
It's just that I already have PCBs for a plain LCD display, but maybe it's worth it to order new ?
For the price of not cutting the hole in the housing. Something for something.

Online gflorez

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Re: 6Mhz and more...
« Reply #229 on: 2019.March.14. 10:02:49 »
I will love to try your screen version and later the OSD version.

In my tests of EXTC I had very bad display from my defective-NIck Enterprise and perfect on the other, so probably it is better to put a little screen on these computers.

Offline pear

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Re: 6Mhz and more...
« Reply #230 on: 2019.March.15. 05:53:32 »
In this case, the OSD project goes to the shelf "for later".
First, I need have to finish the "basic" version.
« Last Edit: 2019.March.15. 07:59:42 by pear »

Offline Zozosoft

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Re: 6Mhz and more...
« Reply #231 on: 2019.September.10. 11:11:21 »
First, I need have to finish the "basic" version.
There is any news? :oops:

Offline pear

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Re: 6Mhz and more...
« Reply #232 on: 2019.September.10. 15:05:06 »
A bit of shame, but no :oops:
I am stuck in life trifles :|

Offline elmer

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Re: 6Mhz and more...
« Reply #233 on: 2021.January.28. 21:57:34 »
The hw design of the Enterprise is originally ready for 6MHz model. The most important evidence about it is the option bit in the Dave (at port BFh), set the Dave sound frequency divider for the 4 or 6 Mhz system.
Very strange - why was 6Mhz machine not released?
Originally only 3 modifications needed:
-Z80B instead of Z80A
-12MHz crystal instead of 8MHz
-modify one bit in the EXOS code, for setting right frq for Dave

Just to make sure that I understand you correctly  ...

If I don't want to use an external EXDOS/Floppy board, and I don't ever want to attach anything else to the Expansion Slot ... then all that I need to do to create a 6MHz Enterprise is to burn a new EXOS EPROM, and to replace the motherboard's 8MHz crystal with a 12MHz crystal?

Something like this or this?


I understand that some (maybe a lot) of games won't play well at the higher speed, and that some (maybe a lot) of games reset Dave's clock divider and so will sound wrong ... but that still seems way too easy! :shock:

Offline Zozosoft

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Re: 6Mhz and more...
« Reply #234 on: 2021.January.28. 22:04:46 »
Yes!
Many games will be better on 6MHz. For example in the Race Ace only your car will be faster :-) (computer cars are synced with video irq)
« Last Edit: 2021.January.29. 16:47:13 by szipucsu »

Offline dangerman

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Re: 6Mhz and more...
« Reply #235 on: 2021.January.28. 22:35:10 »
If I don't want to use an external EXDOS/Floppy board, and I don't ever want to attach anything else to the Expansion Slot ... then all that I need to do to create a 6MHz Enterprise is to burn a new EXOS EPROM, and to replace the motherboard's 8MHz crystal with a 12MHz crystal?

That's right. I have done exactly that and it's great. A lot of Z80 chips run fine at 6Mhz. You don't actually even need to change the EXOS ROM. The Dave register can be changed in software or by the SD-card ROM.

As you say, there are some issues. You can't use the floppy drives without keeping the 8Mhz clock for the expansion port. And the serial driver baud rates are wrong at 12Mhz etc. etc.

Offline dangerman

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Re: 6Mhz and more...
« Reply #236 on: 2021.January.28. 22:38:43 »
Btw, the fast startup code in EXOS2.4 or on the SD cartridge automatically sets up the Dave register correctly, so if you use either of those no change is needed.

Offline elmer

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Re: 6Mhz and more...
« Reply #237 on: 2021.January.30. 05:35:06 »
Yes!

Woohoo, I forsee having an almost-PW320 in my near future! :ds_icon_cheesygrin:


A lot of Z80 chips run fine at 6Mhz.

I would be great if I get lucky, but if not, then I'm fortunate to be living in the USA, because there are still a couple of sellers here with old 6MHz NMOS Z80s.


And the serial driver baud rates are wrong at 12Mhz etc. etc.

That would be one good reason to remove the Z80 from the Enterprise motherboard, and install a socket.

Putting in a Z8S180 would allow me to also use a high-speed 5V USB-to-serial adapter for testing code.

But maybe that's just a bit more than I have the skills to do, and anyway, I don't think that the motherboard would still fit in the Enterprise case! ;-)


Btw, the fast startup code in EXOS2.4 or on the SD cartridge automatically sets up the Dave register correctly, so if you use either of those no change is needed.

I am using EXOS 2.4, so that's good!

Since the Dave register is read-only, is there an EXOS variable that I can read to detect the current CPU speed and Dave setting?

Offline geco

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Re: 6Mhz and more...
« Reply #238 on: 2021.January.30. 09:41:14 »
i do not know if there is a variable in exos 2.4, but there are more way to find the cpu speed, set dave 1khz interrupt counter, and count them within 50hz video interrupt, and based on the number it can be decided cpu speed.

Offline elmer

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Re: 6Mhz and more...
« Reply #239 on: 2021.January.31. 23:44:09 »
i do not know if there is a variable in exos 2.4, but there are more way to find the cpu speed, set dave 1khz interrupt counter, and count them within 50hz video interrupt, and based on the number it can be decided cpu speed.

Thanks! :)

Yes, I've seen the thread with some example code to do that test.

I was hoping that there might be some EXOS variables to look at, but I guess that it's not very surprising that there aren't ... things like that may have been added to later versions of EXOS.


In the same way, I have just been looking for an EXOS variable with a 50Hz interrupt count, but I can't seem to find one.

The fast blink rate of the cursor on an "EDITOR:" screen is starting to get annoying, especially when running a 6MHz Enterprise emulation in EP128EMU.

The fast video driver in IS-DOS uses the video interrupt for drawing a cursor, while looks much nicer to me than the EXOS "EDITOR:" device's use of a software delay loop.