1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>Chapter 2. Driver Modes</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="Z8530 Programming Guide"><link rel="up" href="index.html" title="Z8530 Programming Guide"><link rel="prev" href="intro.html" title="Chapter 1. Introduction"><link rel="next" href="Using_the_Z85230_driver.html" title="Chapter 3. Using the Z85230 driver"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 2. Driver Modes</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="intro.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="Using_the_Z85230_driver.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="Driver_Modes"></a>Chapter 2. Driver Modes</h1></div></div></div><p> 2 The Z85230 driver layer can drive Z8530, Z85C30 and Z85230 devices 3 in three different modes. Each mode can be applied to an individual 4 channel on the chip (each chip has two channels). 5 </p><p> 6 The PIO synchronous mode supports the most common Z8530 wiring. Here 7 the chip is interface to the I/O and interrupt facilities of the 8 host machine but not to the DMA subsystem. When running PIO the 9 Z8530 has extremely tight timing requirements. Doing high speeds, 10 even with a Z85230 will be tricky. Typically you should expect to 11 achieve at best 9600 baud with a Z8C530 and 64Kbits with a Z85230. 12 </p><p> 13 The DMA mode supports the chip when it is configured to use dual DMA 14 channels on an ISA bus. The better cards tend to support this mode 15 of operation for a single channel. With DMA running the Z85230 tops 16 out when it starts to hit ISA DMA constraints at about 512Kbits. It 17 is worth noting here that many PC machines hang or crash when the 18 chip is driven fast enough to hold the ISA bus solid. 19 </p><p> 20 Transmit DMA mode uses a single DMA channel. The DMA channel is used 21 for transmission as the transmit FIFO is smaller than the receive 22 FIFO. it gives better performance than pure PIO mode but is nowhere 23 near as ideal as pure DMA mode. 24 </p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="intro.html">Prev</a> </td><td width="20%" align="center"> </td><td width="40%" align="right"> <a accesskey="n" href="Using_the_Z85230_driver.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 1. Introduction </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 3. Using the Z85230 driver</td></tr></table></div></body></html> 25