Hardware / Western Digital / WD1002S-WX2

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A very simple 8 bit controller from Western Digital

This MFM controller looks almost the same as the WD1002S-WX2A. In contrast to my WD1002S-WX2A it has a lot of jumpers which are not needed because the default settings are used.

The jumpers at W5 (ROM Size) and W7 (IRQ5) are not needed, because PINs 1-2 are hard wired. You can see this when you look at the PCB against the light!

System Resources

BIOS

The BIOS is basically of type 2764, i.e. it is 8 KByte in size. On this card an EPROM from Fujitsu (MBM2764) is used. Sticker on BIOS: ASD2-0. I read the BIOS with my GALEP-5 EPROM burner and burned it to an EEPROM AT28C64B for testing. Then put the AT28C64B into the card and see there, it works fine.

But the actual BIOS is only 0x700 byte large, i.e. not even 2 KByte. Probably the 2764 chips were just on sale! There are also cards that have a 2732 chip (4 KByte); see (minuszerodegrees).

The (my!) WX2 BIOS is identical to that of the WX2A. I swapped both. The BIOS contains the following strings:

(C) Copyright 1984 Western Digital Corporation
WX2 Format Revision 7.0 (C) Copyright Western Digital Corp. 1985
Formatter as of 02/07/85

Figures

WD1002S-WX2
WD1002S-WX2 (1984)

Unlike the IT-805 controller, the WD1002S-WX2 has only a very rudimentary low-level formatting routine (WX2FMT). You can only select the desired drive and the interleave factor. That was it, unfortunately. See also here

WD1002S-WX2A
WD1002S-WX2A / PRE-FORMAT UTILITY
Start low level formatting with: DEBUG (ENTER) -G=C800:5 (ENTER)

In contrast to the CTT IT-805 (1:1), I can only set the interleave factor to 1:4. More is not possible on my IBM PC XT 5160. I tested both controllers with the same Seagate ST225 and checked them with SpinRite II.

Type and number of supported hard disks depends on the BIOS revision. I have the revision ASD2-0. This is not mentioned in TH99 nor in the OEM manual.

Special note! The drive jumper settings in TH99 are different from the OEM manual!

I just picked the same settings as for the WD1002S-WX2A and it fits (SW1/1-4 = 1111). I almost exclusively use the Seagate ST225. The ST225 is actually supported by every controller.

My two WD1002S-WX2A and -WX2 controllers are compatible, i.e. you can use the same hard disks on both controllers. I set up a ST225 with the WX2A, then changed the controller (WX2) and it works.

Manuals

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