External clock generator for msx, is it possible?

Paladin (763)

29-03-2016, 11:06

Yes,
a friend build it for me, it's an easy idea based on it : http://msx.hansotten.com/uploads/msxdocs/turbo7mhz.pdf
use the original clock generator and/or external.

+First replace the z80, now msx has a 20mhz z80(with socket) instead of original z80a
+Put a external swicth in msx that allows use the original clock generator (3,56mhz without turbo) or select the external clock input using the msx slot, it uses pin5: external clock and pin16: for connect diode to the z80 iorq

If you do it in all your msx, you need only a clock generator cartridge for all your msx(it can be implemented in a mfrsd or other cartridge).

Cable must be shortest way as possible from msx slot to z80.

You can switch different mhz clock speed:
3/6
3.56/7.1
4/8
4.5/9
5/10

Tested in:
philips vg8020/00 using slot1 or slot 2 (running abadia del crimen 9mhz for example)
philips vg8235/20 using slot2 near z80 shortest way (dizzy balloon 10mhz for example)

cartridge photo:
http://msx.pics/image/92PN
http://msx.pics/image/9ebs
http://msx.pics/image/9zpR

Best regards

By Lord_Zett

Paladin (807)

29-03-2016, 19:13

hmmm nice

By syn

Prophet (2148)

29-03-2016, 19:40

What are the advantages of using an external clock generator compared to the older conventional "turbo" upgrades?

By usuario_msx2

Paladin (763)

30-03-2016, 01:04

*you can use a unique clock generator for all your msx computer
*you can change different clock speed using the cartridge switch
*you can test different external clock generator circuit
For example

By spacemoai1973

Ambassador (0)

30-03-2016, 18:48

And make a slot full
maybe stupid quetsion but why do you want to run at 4 or 5 megahertz.?
If I understand good you must still put 20mhz z80 in all your msx

By Pencioner

Scribe (1633)

30-03-2016, 19:36

I have a breadboard and would like to solder one for myself. Do you have a circuit in file (jpeg or bmp)? I know that with patience i could draw the schematics from supplied photos but it's a lot of efforts and time

By usuario_msx2

Paladin (763)

30-03-2016, 20:42

spacemoai1973 wrote:

And make a slot full
maybe stupid quetsion but why do you want to run at 4 or 5 megahertz.?
If I understand good you must still put 20mhz z80 in all your msx

Yes a full slot,
install it in a mfrsd (for example) instead of a test pcb and problem solved.
Some games are too slow at 3.56mhz. gunfright for example.
test it at 8/9 mhz and be sure you think different about it
Original Z80A can't run at 7mhz of ocurse you must replace
ir with a faster z80

By usuario_msx2

Paladin (763)

30-03-2016, 20:23

Pencioner wrote:

sorry
I haven't schematics for it because I use the schematics in the .pdf file in the first post
Following the schematics, you can do it

By spacemoai1973

Ambassador (0)

30-03-2016, 21:06

usuario_msx2 wrote:

spacemoai1973 wrote:

And make a slot full
maybe stupid quetsion but why do you want to run at 4 or 5 megahertz.?
If I understand good you must still put 20mhz z80 in all your msx

But if you must replace the z80 you can also replace the clock. And 9mhz is too fast for the VDP so you must solve that problem before you can play gunfight
This is how they say a solution waiting for a problem.?

By Pencioner

Scribe (1633)

30-03-2016, 21:10

usuario_msx2 wrote:

sorry
I haven't schematics for it because I use the schematics in the .pdf file in the first post
Following the schematics, you can do it

Yeah i understand but the schematic is not exactly the same, it's improved with the multiselect frequency switches and some serial communications controller - that's why i asked. No prob, thanks anyway, i hope to get enough motivation to reverse engineer it once.

By usuario_msx2

Paladin (763)

30-03-2016, 21:57

Pencioner wrote:

for switches: circuit need an oscillator input.
YOU MUST SELECT A SINGLE PAIR OF SWITCHES ON ALL OTHER OFF
Pin switch 1, 2 on (all other off)connect 12mhz osc. to the circuit then 3/6 mhz
..
..
Pin switch 9,10 on (all other off)connect 20mhz osc. yo the circuit then 5/10 mhz
hope it helps you
best regards