NEO-257: Difference between revisions
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*Select: Output A if LOW, B if HIGH. | *Select: Output A if LOW, B if HIGH. | ||
*Some pins marked as ground could be "enable" pins | *Some pins marked as ground could be "enable" pins | ||
**35 is active high enable atleast for Y8~Y15 | |||
**33 is active low enable atleast for Y8~Y15 (confirmed from NEO-257 connection on a 2 slot). In the example from the pic it appears to be hardwired to always be enabled. | |||
[[Category:Chips]] | [[Category:Chips]] | ||
Revision as of 02:46, 6 May 2012
Quadruple 74HC257 2-to-1 multiplexer with common select line, making 16 switches in one chip. Used in dual slot MVS systems to select one of the two C ROM (and S ROM ?) buses.
Select signal comes from one of the "SLOT" outputs of NEO-F0 ?
Pinout
Information provided by Channelmaniac.
OpenOffice Draw file: File:Neo-257.odg
- A*,B*: Inputs
- Y*: Outputs
- Select: Output A if LOW, B if HIGH.
- Some pins marked as ground could be "enable" pins
- 35 is active high enable atleast for Y8~Y15
- 33 is active low enable atleast for Y8~Y15 (confirmed from NEO-257 connection on a 2 slot). In the example from the pic it appears to be hardwired to always be enabled.