A very simple 8 bit controller from Western Digital
This controller was sold with a lot of different BIOS revisions (..., G, H, X, Super BIOS, ...) and this is exactly the problem. Each of these revisions partly supports different hard disk types. Therefore it is, with a few exceptions, very difficult to set the correct type. One of these exceptions is the Seagate ST225 or comparable types.
So far I couldn't find any further manuals about this controller on the internet. There is only the usual overview on "Total Hardware 1999".
System Resources
- ROM BIOS: 0xC8000
- I/O Port: 0x320
- IRQ: 5
Revision "X1"
ROM BIOS
The BIOS is also of type 2764, i.e. it is 8 KByte in size. On this card an EPROM from SEEQ is used. Sticker on BIOS: 62-000049-031. This EPROM is compatible to EPROM FUJITSU MBM2764 and ... I read the BIOS with my GALEP-5, „burned“ it to an EEPROM ATMEL AT28C64B. Then put the AT28C64B into the card and see there, it works fine.
This BIOS is only 0x700 byte in size, i.e. not even 2 KByte. Probably the 2764 chips were just on sale! But there are also cards that have a 2732 chip (4 KByte); see (minuszerodegrees).
The BIOS on my WX2A card is identical to that on my WX2 card. 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
Unlike the IT-805 controller, the WD1002S-WX2A 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
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. I tested both controllers with the same Seagate ST225 and checked them with SpinRite II.
This controller is also kept very simple with regard to the possible settings. There are virtually no jumpers, although the TH99 data sheet mentions some. Actually there are only the jumpers/switches (SW1) for the selection of the hard disks.
Type and number of supported hard disks depends on the BIOS revision. I have the revision X1. This is not mentioned in TH99.
In my case, I just picked the number 0 (REV G) and ... it fits for the ST225 (SW1/1-4 = 1111). I almost exclusively use the Seagate ST225. The ST225 is actually supported by most 8 bit controller cards.
Note: You do not have to set jumper SW1/8. On an XT it is normally open.
Coincidentally my two WD1002S-WX2A and -WX2 controller cards 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.
Revision "X12" / A modded card
Have a closer look at U5 and U7. Here an additional capacitor and resistor were soldered in. This PCB is different to Rev. "X1"!
What is the proper identifier, "X2" or "X/2" or "X12"? Since in my opinion there was originally written "X8" on the sticker, I think it must be called "X12". But I could be wrong.
Update: On ebay a card with the revision "X7" is currently (28.12.2019) offered (US $29.95) with the same BIOS sticker (62-000094-031); but without the above mods.
ROM BIOS
The BIOS is also of type 2764, i.e. it is 8 KByte in size. On this card an EPROM from SEEQ is used. Sticker on BIOS: 62-000094-031. This EPROM is compatible to EPROM FUJITSU MBM2764 and ... I read the BIOS with my GALEP-5, „burned“ it to an EEPROM ATMEL AT28C64B. Then put the AT28C64B into the card and see there, it works fine.
This BIOS is nearly 8 KByte in size and therefore much larger than in Rev "X1". Another special feature: The PRE-FORMAT UTILITY is different, newer and slightly better. Now you can „really“ use an INTERLEAVE of 3. With Rev "X1" only 4 were useable with my IBM PC XT 5160.
07/15/86 (C) Copyright 1986 Western Digital Corp.
WX2Format Revision 1.0S Copyright Western Digital Corp. 1986
Manuals
- Total Hardware 1999: Jumpers and switches (WD1002S-WX2A)
Downloads
- ROM BIOS for Rev. "X1": Download (8 KByte) / The chip is of type "2764". I tested the BIOS with an ATMEL AT28C64B (EEPROM); works fine. Since the BIOS is only 0x700 byte, a 2732 chip is sufficient. There are also cards with a 2732 chip.
- ROM BIOS for Rev. "X12": Download (8 KByte) / The chip is of type "2764". I tested the BIOS with an ATMEL AT28C64B (EEPROM); works fine.