GEM's Fast 20 LB Comments

Gene at notes.seagate.com Gene at notes.seagate.com
Tue Jan 3 12:50:35 PST 1995


I am voting No. However the No will automagically change to Yes with 
satisfactory correction to the problems pointed out in comments 19, 23, 24, 26, 
and 28.

1) Upon forwarding delete the document status page.

2) The foreword states that the requirements of SPI also apply except where 
specifically stated otherwise in Fast -20. I get the impression the opposite 
convention was used. The standard seems to specifically state when SPI applies. 
Examples are found in the Scope, the citing that the higher layer service 
interface is specified by SPI, and the note demurring on the slow and 
asynchronous times. I dont think there are any instances of the standard 
specifically stating that SPI does not apply.

3) Change the next to last paragraph of the foreword from and voting procedures 
of the American National Standards Institute to and voting procedures 
accredited by the American National Standards Institute.

4) Why is SIP not included in the Normative references? If the reason is that 
it is covered by SPI, the why are the EIA/TIA and ISO references included?

5) Why both RS-485 and ISO 8482?

6) What is the / at the end of Note 1?

7) Change definition 3.1.7 to ... rate stated in millions at which words ... or 
to ... rate at which a million words ....

8) Change definition 3.1.14 to A slow synchronous data transfer with negotiated 
transfer perios of at least 200 nanoseconds.

9) Delete SCSI from definition 3.1.16.

10) It seems over kill to include (FAST-20) as an achronym for Fast-20 in 
Section 4. In addition the achronym is not capitalized consistently throughout 
the standard.

11) The first and third paragraphs of 5.1 are redundant. In spite of the 
redundancy they fail to address whether or not 9 SCSI devices are legal in some 
configuration. Depending upon how and if the third paragraph survives, change 
cannot be to shall not be or if the i.e. does not allow this , change it to are 
not.

12) What aspect is the 50 mV a requirement on? Does it change the wire gage 
requirements of SPI? Does it change the maximum current of the drivers? Or is 
it a further requirement on the non SCSI power bussing?

13) Does the lack of any statement on the number of devices and composition of 
the devices in 5.2 imply that 8, 16, and 32 bit devices can be intermixed with 
differential?

14) Change the first line of Seciton 6 to from can use to allows.

15) Contrary to the first paragraph of 6.1.1 I thought Fast 20 was going to 
discourage internal termination. Why not either outlaw them or as a minimum 
delete the last sentence in 6.1.1?

16) In this same section in item (f) there is a forward or backward reference 
to oblivion. Item (b) of 6.1.4 has a similar problem.

17) In Note 4 change to 15 pF to to less than 20 pF or to less than 16 pF.

18) In the first line of 6.2.1 change al to all. Apparently the spell checker 
is set to accept et al or the spell checker needs to be run. The latter 
conclusion is supported by referenc in Note 4 of Table 1 which needs an e.

19) Figure 2 has the wrong grafic. This is not the differential termination.

20) In Annex A the depiction of the 15 ns components needs work.

21) In the second paragraph of Annex C change When capacitance added to When 
capacitance is added.

22) The method of calling out Note 1 is differant than in the body of the 
standard. in any case it would be clearer what long(1) meant if note 1 was 
moved to the prior page. 

23) The second equation should take the place of (equation) and the where VLO 
should come after the equation with the LO and J1 font adjusted for subscript.

24) In this equation L1 should actually be a subscript to a missing V.

24) Similary the location of  the third and fourth equations need to be 
adjusted to replace there  (equation) place holders.

25) The kearning of 3.7 and 0.27 need to be adjusted.

26) Just before the last set of equations a reference is amde to equation (1), 
however only the hodpodge 2) is actually identified. If they are to be referred 
to by number, each equation should be numbered. 

27) To the right of the and it would be better if the three inequalities had 
three disticnt separating blank lines. It would also be better to have 85 pf/m 
all on the same line.

28) The text of Annex C ends with the statement This. What is missing?

29) On the vertical axis of Figure 1 in Annex C change (m to (m).


Gene Milligan





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