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1 | Some notes for ftape users with PCI motherboards: | ||
2 | ================================================= | ||
3 | |||
4 | The problem: | ||
5 | ------------ | ||
6 | |||
7 | There have been some problem reports from people using PCI-bus based | ||
8 | systems getting overrun errors. | ||
9 | I 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. | ||
11 | It turned out that if GAT (Guaranteed Access Timing) is enabled (?) | ||
12 | ftape gets a lot of overrun errors. | ||
13 | The problem disappears when disabling GAT in the bios. | ||
14 | Note that Intel removed this setting (permanently disabled) from the | ||
15 | 1.00.10AX1 bios ! | ||
16 | |||
17 | It 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 | ||
19 | service the floppy disk controller. | ||
20 | I cannot imagine this being acceptable in a decent PCI implementation. | ||
21 | Maybe this is a `feature' of the chipset. I can only speculate why | ||
22 | Intel choose to remove the option from the latest Bios... | ||
23 | |||
24 | The lesson of this all is that there may be other motherboard | ||
25 | implementations having the same of similar problems. | ||
26 | If you experience a lot of overrun errors during a backup to tape, | ||
27 | see if there is some setting in the Bios that may influence the | ||
28 | bus timing. | ||
29 | |||
30 | I judge this a hardware problem and not a limitation of ftape ;-) | ||
31 | My DOS backup software seems to be suffering from the same problems | ||
32 | and even refuses to run at 1 Mbps ! | ||
33 | Ftape will reduce the data-rate from 1 Mbps to 500 Kbps if the number | ||
34 | of overrun errors on a track exceeds a threshold. | ||
35 | |||
36 | |||
37 | Possible solutions: | ||
38 | ------------------- | ||
39 | |||
40 | Some of the problems were solved by upgrading the (flash) bios. | ||
41 | Other suggest that it has to do with the FDC being on the PCI | ||
42 | bus, 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 | ||
44 | a floppy disk controller on the isa-bus]. | ||
45 | |||
46 | Here is a list of systems and recommended BIOS settings: | ||
47 | |||
48 | |||
49 | Intel Premiere PCI (Revenge): | ||
50 | |||
51 | Bios version 1.00.09.AF2 is reported to work. | ||
52 | |||
53 | |||
54 | |||
55 | Intel Premiere PCI II (Plato): | ||
56 | |||
57 | Bios version 1.00.10.AX1 and version 11 beta are ok. | ||
58 | If using version 1.00.08.AX1, GAT must be disabled ! | ||
59 | |||
60 | |||
61 | |||
62 | ASUS PCI/I-SP3G: | ||
63 | |||
64 | Preferred settings: ISA-GAT-mode : disabled | ||
65 | DMA-linebuffer-mode : standard | ||
66 | ISA-masterbuffer-mode : standard | ||
67 | |||
68 | |||
69 | DELL Dimension XPS P90 | ||
70 | |||
71 | Bios version A2 is reported to be broken, while bios version A5 works. | ||
72 | You can get a flash bios upgrade from http://www.dell.com | ||
73 | |||
74 | |||
75 | To see if you're having the GAT problem, try making a backup | ||
76 | under DOS. If it's very slow and often repositions you're | ||
77 | probably 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 | ||