1Some notes for ftape users with PCI motherboards:
2=================================================
3
4The problem:
5------------
6
7There have been some problem reports from people using PCI-bus based
8systems getting overrun errors.
9I wasn't able to reproduce these until I ran ftape on a Intel Plato
10(Premiere PCI II) motherboard with bios version 1.00.08AX1.
11It turned out that if GAT (Guaranteed Access Timing) is enabled (?)
12ftape gets a lot of overrun errors.
13The problem disappears when disabling GAT in the bios.
14Note that Intel removed this setting (permanently disabled) from the
151.00.10AX1 bios !
16
17It looks like that if GAT is enabled there are often large periods
18(greater than 120 us !??) on the ISA bus that the DMA controller cannot
19service the floppy disk controller.
20I cannot imagine this being acceptable in a decent PCI implementation.
21Maybe this is a `feature' of the chipset. I can only speculate why
22Intel choose to remove the option from the latest Bios...
23
24The lesson of this all is that there may be other motherboard
25implementations having the same of similar problems.
26If you experience a lot of overrun errors during a backup to tape,
27see if there is some setting in the Bios that may influence the
28bus timing.
29
30I judge this a hardware problem and not a limitation of ftape ;-)
31My DOS backup software seems to be suffering from the same problems
32and even refuses to run at 1 Mbps !
33Ftape will reduce the data-rate from 1 Mbps to 500 Kbps if the number
34of overrun errors on a track exceeds a threshold.
35
36
37Possible solutions:
38-------------------
39
40Some of the problems were solved by upgrading the (flash) bios.
41Other suggest that it has to do with the FDC being on the PCI
42bus, but that is not the case with the Intel Premiere II boards.
43[If upgrading the bios doesn't solve the problem you could try
44a floppy disk controller on the isa-bus].
45
46Here is a list of systems and recommended BIOS settings:
47
48
49        Intel Premiere PCI (Revenge):
50
51Bios version 1.00.09.AF2 is reported to work.
52
53
54
55        Intel Premiere PCI II (Plato):
56
57Bios version 1.00.10.AX1 and version 11 beta are ok.
58If using version 1.00.08.AX1, GAT must be disabled !
59
60
61
62        ASUS PCI/I-SP3G:
63
64Preferred settings:     ISA-GAT-mode : disabled
65                        DMA-linebuffer-mode : standard
66                        ISA-masterbuffer-mode : standard
67
68
69        DELL Dimension XPS P90
70
71Bios version A2 is reported to be broken, while bios version A5 works.
72You can get a flash bios upgrade from http://www.dell.com
73
74
75To see if you're having the GAT problem, try making a backup
76under DOS. If it's very slow and often repositions you're
77probably having this problem.
78
79                        --//--
80 LocalWords:  ftape PCI bios GAT ISA DMA chipset Mbps Kbps FDC isa AF ok ASUS
81 LocalWords:  SP linebuffer masterbuffer XPS http www com
82