HOOKING UP SCSI ZIP DRIVE TO FIRST X68000(CZ-600C)'S HDD CON. (PICS UPDATED)

[netwalka]

Hello, X68000 users.

Recently, I've got a chance to deal with the first X68000 (cz-600c) from my friend,








and tried to follow the well-known "SXSI driver on SASI machine" method,

but this mehod didn't work.

SXSI driver hungs on recoginzing ZIP drive or IDE-to-SCSI bridge board(BUFFALO/MELCO), they didn't boot to Human68k.

So, I made my mind to build a parity generation circuit, even though it's too cold to ventilate solder hume thru window in this cold cold winter....

As you guys all know, there is a parity generation schematics for SXSI driver on the web.



▲ I found this schematics from the blog below, he is a real awesome genius!!

I assume the 74ACT280 is used for timing issue.

sabaiwashi.blog112.fc2.com/blog-entry-203.html




...Then, I opened the X68000.

The fist X68000 doesn't have room for internal HDD,

So I  planned to add the parity generation circuit to the "external HDD and FDD PCB"

and to connect ZIP100 drive to the HDD connector (SASI type)



▲ this is the "external HDD and FDD PCB" of the first X68000.

Little bit different from the ones of ACE and EXPERT models

Looking at the solder side of the PCB and there is 26 pin IDC connector that comes from the bottom control board.(marked "HC")

26pin maybe remind you the SCSI internal connector of SUPER and XVI model,

but pin map is totally different and this is SASI type not SCSI.

Even the CZ-600C is SASI based model,

this 26 pin cable is different from the 20 pin ones of ACE, EXPERT, so I had to tried to find the purpose of each pins.

I referred the first X68000's service manual and pinout of SCSI CN50 connector.




And double-checked the pinout of the solder side of the PCB.




▲ This is the result of the research.


I guess the D0~D7 signal inputs to the 74ACT280 are intended to be derived from the control board of the bottom of X68000,
but, I did it just on the "external HDD and FDD PCB" for convenience.

(Because, the D0~D7 signal on the "external HDD and FDD PCB" is already pass through the bunch of 220 ohm and 330 ohm resistor network.
Unlike the ACE and EXPERT models, this first X68000's "external HDD and FDD PCB" doesn't have resistor network on it,
So I think, those resistors are on the bottom PCB of X68000.)



Anyway, this schematics works fine and just forget about the orders.
Whether D signal comes from before resistor network or after resistor network, it works!!





▲ Finished the work, shivering with cold....

(I need to manage proper vent system for winter. T^T)




Now, the SXSI driver recognize SCSI type ZIP100 drive

and I formatted the ZIP100 disk and this boots itself fine.

And my friend is happy enough. 'Cause He had just made bunch of diskettes to play games till now.


I'm not sure this "parity generation circuit" is indispensable to connect ZIP drive or MO drive to SASI based models

including the first and ACE, EXPERT etc.

But, definitely, this work helps to improve compatibility.


Thank you for reading my post.

[eidis]

 Hi Netwalka !

Congratulations on a job well done ! Very clean and efficient design. Keep up the good work and...

Keep the scene alive !
Eidis