Yes, two outputs makes the device much more versatile.

And surely Zozo wants to tweak the Z80 and the EXDOS at the same time....

The original setup:
One 8MHz System Clock on the motherboard. This going to the Nick chip which is generate the 4MHz CPU clock (which is delayed when video memory accessed). This 8MHz also going out on the expansion connector and used by the EXDOS as clock for WD chip.

At the turbo Enterprise one or more new System Clock generators added: 12MHz , 14.xxxMHz (using Video Clock), 20Mhz (4/6/7.12/10MHz CPU). These are switchable.
The original System Clock line cutted from the expansion connector, and the original 8MHz wired out for keep the disk controller working.

On the Turbo EXDOS using the original 8MHz from the machine, and 3 new clock added: 10MHz/13.333MHz/16MHz or 10MHz/9.6MHz/16MHz. Values depend from 1.2MB drive used in 300 or 360 rpm mode.
10MHz -> "Turbo DD", using 13 sectors 1040K on 80 tracks disk (1170K with 90 tracks). This is my first Turbo EXDOS hack, later added the HD hack:
13.333MHz -> using HD disks in 300 rpm mode ("Enterprise jumpered") 1.2MB drive
16MHz -> using HD disks in 1.44MB drive (22 sectors possible = 1760K on 80 tracks)

Then discovered the Turbo EXDOS can solve the non "Enterprise jumperable" 1.2MB drives problem, which are running on 360 rpm. Then the 13.333 crystal replaced with 9.6MHz -> can use normal DD disks. For the HD mode the 16MHz used.
(At this situation these drive can not handle the "Turbo DD" disks, for these needed add another extra clock: 12MHz...)


Only problem with the HD disks: the 4MHz Z80 not enought fast for the data transfer, the machine also need to be run on Turbo.
Soo, if the Turbo EXDOS for HD also need a Turbo Enterprise, then will be good ide if the internal Turbo card can supply both clocks! If both software controlled then the EXDOS can switch Turbo on CPU when needed (using HD disks).

Summary, the "Dream Turbo Card" have a two independent clock output, one for the machine System Clock, and one for the EXDOS. Both software controllable on I/O port, and current setting can be readed.
For the System clock need external push button input, for speed select (during game you can not enter command for select the speed). For example the System Clock speeds are 4/8/12/16/20MHz (2/4/6/8/10MHz Z80)
Speeds for EXDOS 8/9.6/10/12/13.333/16MHz

If this "Dream Turbo Card" can be done, then not need modify EXDOS card, just need to use proper WD chips for the HD mode (WD1772 PH 02-02).

One more question: the "frozen free" CPU clock switching.
The SMD Team Turbo Card do it. But the IC types erased for the copy protection...

My low cost turbo don't "frozen free" With modern CMOS CPU, and with 74F153 (as clock switch) and good quality switches are almost working the frozen free switching, but not always.

Probably the CPU don't like spikes on the clock signal.

Do you have a idea for it? Or probably the software controlled clock generator made the clock switching without spikes?

(My idea for discover the SMD turbo: remove the ICs, and test in IC tester, until find the right types... but if only you not have any better idea!)

WD1772 don't have a problem with clock switching.

And the most important extra feature: the Turbo LED
My idea using RGB LED (can be placed to the power led place), and using colors from the Enterprise logo: 2MHz blue, 4MHz green,6MHz yellow,8MHz orange,10MHz red.

Test board in development.

In case, if I want to change the destination of the port in the microcontroller, just enough cut the path between the pads, and connect other signal.
For example, as in the picture.

PS. I have already ordered the test board.

looks cool

After optimization I need only 2 clocks: 40 and 48 MHz. The final cost goes down

It was a sudden thought. A spark