modem7
10k Member
My efforts in getting a Seagate ST-506 to work in a 5150 (or 5160)
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The story below happened a few months ago. I'm posting it now because I can see that there is an ST-506 on eBay presently (with more to follow), and I want people to realise that getting the ST-506 to work in a 5150 or 5160 (or 5170 for that matter) is not straightforward.
The first thing you need to know about the ST-506 is that it requires a 3 millisecond (not microseconds) step rate, and nothing else. Not many HDD controllers for the 5150/5160 give you the option of using a 3 millisecond step rate, and so that is the first hurdle.
This 'early' drive also requires a 'reduced write current' signal (on cylinders 128 and onwards) from the controller. Note that 'reduced write current' is not the same as 'write precompensation'.
Even having controllers that met both criteria, I still had problems. They would work set at a 3mS step rate when connected to an ST-138, but had a problem when configured for the ST-506. I saw problems like:
1. Starts low level format but controller gives an error somewhere near last cylinder.
2. Starts low level format but controller gives an error when the heads return to cylinder 0.
3. Low level format completes without error, FDISK then FORMAT/S completes without error, but drive won't boot.
A friend found a web site (http://files.chatnfiles.com/RBBS in a Box/DULL/DTCCNTRL.NFO) where it was shown how to modify the ROM in a DTC 5150BX.
That fiend had a DTC 5150BX and so I started to create a modified' ROM for it.
The starting address for the drive parameter table was different to that specified (due to a different ROM revision no doubt) but the drive parameter table was in the same rough location.
I modified the entry for drive #7 (unused) to match the ST-506 as follows:
9900 (153 cylinders)
04 (4 heads)
8000 (reduced write current starts at cyl 128)
8000 (WPC starts at cyl 128)
0B (ECC burst)
00 (step rate = 3 ms)
FF (drive-ready timeout)
FF (format timeout)
FF (general timeout)
00 (always 00)
00 (always 00)
00 (always 00)
00 (always 00)
I also had to modify an unused byte (near the end) to take the 8 bit checksum to 00.
SUCCESS - ST-506 worked beautifully.
So the solution was the use of a "DTC 5150BX that has a suitably modified BXD06 ROM".
I subsequently obtained a DTC 5150CX (a later generation DTC board) with a revision BXD07 ROM. I tried the same technique, but it failed. But I discovered that inserting the modified BXD06 ROM instead of the modified BXD07 ROM worked.
Also to note that is that once I had the system running, I found that the SpeedStor 6.0.5 hard drive utility reported the connected drive as much bigger than 5MB. Why? I don't know. And a bounded read test (restricted to 4 heads, 150 cyl) failed. Not sure what's going on there because a different diagnostic tool (can't remember which one) tested the drive as good.
------------------------------------------------------------------
The story below happened a few months ago. I'm posting it now because I can see that there is an ST-506 on eBay presently (with more to follow), and I want people to realise that getting the ST-506 to work in a 5150 or 5160 (or 5170 for that matter) is not straightforward.
The first thing you need to know about the ST-506 is that it requires a 3 millisecond (not microseconds) step rate, and nothing else. Not many HDD controllers for the 5150/5160 give you the option of using a 3 millisecond step rate, and so that is the first hurdle.
This 'early' drive also requires a 'reduced write current' signal (on cylinders 128 and onwards) from the controller. Note that 'reduced write current' is not the same as 'write precompensation'.
Even having controllers that met both criteria, I still had problems. They would work set at a 3mS step rate when connected to an ST-138, but had a problem when configured for the ST-506. I saw problems like:
1. Starts low level format but controller gives an error somewhere near last cylinder.
2. Starts low level format but controller gives an error when the heads return to cylinder 0.
3. Low level format completes without error, FDISK then FORMAT/S completes without error, but drive won't boot.
A friend found a web site (http://files.chatnfiles.com/RBBS in a Box/DULL/DTCCNTRL.NFO) where it was shown how to modify the ROM in a DTC 5150BX.
That fiend had a DTC 5150BX and so I started to create a modified' ROM for it.
The starting address for the drive parameter table was different to that specified (due to a different ROM revision no doubt) but the drive parameter table was in the same rough location.
I modified the entry for drive #7 (unused) to match the ST-506 as follows:
9900 (153 cylinders)
04 (4 heads)
8000 (reduced write current starts at cyl 128)
8000 (WPC starts at cyl 128)
0B (ECC burst)
00 (step rate = 3 ms)
FF (drive-ready timeout)
FF (format timeout)
FF (general timeout)
00 (always 00)
00 (always 00)
00 (always 00)
00 (always 00)
I also had to modify an unused byte (near the end) to take the 8 bit checksum to 00.
SUCCESS - ST-506 worked beautifully.
So the solution was the use of a "DTC 5150BX that has a suitably modified BXD06 ROM".
I subsequently obtained a DTC 5150CX (a later generation DTC board) with a revision BXD07 ROM. I tried the same technique, but it failed. But I discovered that inserting the modified BXD06 ROM instead of the modified BXD07 ROM worked.
Also to note that is that once I had the system running, I found that the SpeedStor 6.0.5 hard drive utility reported the connected drive as much bigger than 5MB. Why? I don't know. And a bounded read test (restricted to 4 heads, 150 cyl) failed. Not sure what's going on there because a different diagnostic tool (can't remember which one) tested the drive as good.