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IBM PC Family  -  Some documentation errors



Date August 1981
Document IBM 5150 - Technical Reference - First Edition (August 1981)
Page 2-8
Error "and require five clocks or approximately 7% of the bus bandwidth." should be,
"and require four clocks or approximately 5.6% of the bus bandwidth".
Notes • Per page 2-4, refresh DMA cycles are 4 clocks long.
• 4 clocks in 72 equates to 5.6%
• The clock count portion has been corrected in later editions of the manual.



Date August 1981
Document IBM 5150 - Technical Reference - First Edition (August 1981)
Page 2-36
Error "for a maximum of 5 seconds" should be,
"for a minimum of 5 seconds".
Note Seen fixed in the 1984 edition of the manual.



Date April 1983
Document IBM 5160 - Technical Reference - Revised Edition (April 1983)
Page 1-14
Error "and require four clocks or approximately 7% of the bus bandwidth." should be,
"and require four clocks or approximately 5.6% of the bus bandwidth".
Note • 4 clocks in 72 equates to 5.6%, not 7%
• Seen corrected in 'Revised Edition (March 1986)' edition of the 5155/5160 tech. ref.



Date January 1984
Document IBM 5155 - Guide to Operations - First Edition (January 1984)
Page 4-81
Error Wrongly indicates that for 256 KB of motherboard RAM, switch 3 is off and switch 4 is on.
Instead, both switches 3 and 4 must be off.



Date March 1984
Document IBM 5170 - Technical Reference - First Edition (March 1984)
Page 1-77
Error Click here to see.



Date April 1984
Document IBM 5150 - Technical Reference - Revised Edition (April 1984)
Page 1-15
Error "and require four clocks or approximately 7% of the bus bandwidth." should be,
"and require four clocks or approximately 5.6% of the bus bandwidth".
Note 4 clocks in 72 equates to 5.6%, not 7%



Date August 1984
Document IBM Options and Adapters - Serial/Parallel Adapter
Page 20
Error In the diagram, the ports are swapped. Click here to see my correction.



Date September 1985
Document IBM 5170 - Technical Reference - First Edition (September, 1985)
Page 1-4
Error #1 Indicates that a type 1 motherboard has 4 banks of RAM
On a type 1 motherboard, there are only 2 banks, as indicated by the photo at here.

Note: IBM has the bank count correct in the MAR84 edition.
Error #2 Indicates that a type 2 motherboard has 2 banks of RAM
On a type 2 motherboard, there is only 1 bank  (where 1 bank = 16 data chips + 2 parity chips).



Date March 1986
Document IBM 5170 - Technical Reference - Revised Edition (March, 1986)
Page 1-4
Error #1 Indicates that a type 1 motherboard has 4 banks of RAM
On a type 1 motherboard, there are only 2 banks, as indicated by the photo at here.

Note: IBM has the bank count correct in the MAR84 edition.
Error #2 Indicates that a type 2 motherboard has 2 banks of RAM
On a type 2 motherboard, there is only 1 bank  (where 1 bank = 16 data chips + 2 parity chips).



Date March 1986
Document • IBM 5170 - Technical Reference - First Edition (September, 1985)
• IBM 5170 - Technical Reference - Revised Edition (March, 1986)
Page 1-92
Error Click here to see.

Note: Shown correctly on a later page: page 1-113



Date ?????
Document IBM Options and Adapters - Asynchronous Communications Adapter
Page 33
Error In the circuit diagram, jumper J13 is incorrectly labelled as J1.



Date Various
Document Various for IBM 5150 and IBM 5160
Error Reports of IBM getting the switch setting wrong for the math coprocessor.
See here.