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Settings for the 16550 UART FIFO Buffer
Article ID: 131016 - View products that this article applies to.
This article was previously published under Q131016
This article describes the FIFO settings for a 16550 UART chip and how to change them.
Windows 95 provides two methods for accessing the 16550 UART FIFO buffer settings. Each method is a global setting and can affect PCMCIA, internal, and external modems. Use one of the following methods to access the Advanced Port Settings dialog box:
Enable/Disable the FIFO BufferTo disable the FIFO buffer for a 16550 UART chip, click the "Use FIFO buffers (requires 16550 compatible UART)" check box to clear it.
Receive BufferThe Receive Buffer slider supports the values 1 (low), 4, 8, and 14 (high).
The default value of 8 should be sufficient in most cases. If you decrease this value, more interrupts are sent to the processor, slowing bytes into the UART. If you increase this value from 8 to 14, characters may overrun the FIFO buffer.
Transmit BufferThe Transmit Buffer slider supports the values 1 (low), 6, 11, and 16 (high).
If you experience problems uploading files, decrease the default value of 16. If you decrease the buffer from 16, more interrupts are sent to the processor, slowing down the rate at which bytes are sent into the UART Transmit buffer, reducing serial overruns. The higher the number, the fewer interrupts are sent, increasing system performance during uploads.
Article ID: 131016 - Last Review: November 15, 2006 - Revision: 1.1