Model 100 Serial Interface: Difference between revisions
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|Bit || Function || Note | |Bit || Function || Note | ||
|- | |- | ||
|0 || Stop | |0 || Stop Bit Select || 0 → 1 stop bit<br/>1 → 2 or 1.5 stop bits (1.5 if character length is 5, 2 otherwise) | ||
|- | |- | ||
|1 || Even | |1 || Even Parity Enable || 0 → Odd parity<br/>1 → Even | ||
|- | |- | ||
|2 || Parity Inhibit || 0 → Parity<br/>1 → No parity | |2 || Parity Inhibit || 0 → Parity<br/>1 → No parity | ||
|- | |- | ||
|4-3 || Character | |4-3 || Character Length Select || Bits:<br/>00 → 5<br/>01 → 6<br/>10 → 7<br/>11 → 8 | ||
|- | |- | ||
|7-5 || Unused || | |7-5 || Unused || | ||
Revision as of 16:31, 1 February 2009
Overview
The BASIC ROM provides access to the serial port. BASIC ROM support is well documented elsewhere. This article covers direct use of the IM6402 UART on the Model 100 and Tandy 102.
Configuration
Before the serial port can be used, it must be configured both for serial word format (data bits, stop bits, and parity) and baud rate.
Serial Word Format
Port $D8 controls the serial word format.
| Bit | Function | Note |
| 0 | Stop Bit Select | 0 → 1 stop bit 1 → 2 or 1.5 stop bits (1.5 if character length is 5, 2 otherwise) |
| 1 | Even Parity Enable | 0 → Odd parity 1 → Even |
| 2 | Parity Inhibit | 0 → Parity 1 → No parity |
| 4-3 | Character Length Select | Bits: 00 → 5 01 → 6 10 → 7 11 → 8 |
| 7-5 | Unused |
Baud Rate
Data Transmission
Data Reception
I/O Map
| Name | Direction | Port |
| TX | Output | $C8 |
| RX | Input | $C8 |
| RTS | Output | $BA, bit 7 |
| CTS | Input | $BB, bit 4 |
| DSR | Input | $BB, bit 5 |
| DTR | Output | $BA, bit 6 |
Direction indicates both data flow, and whether to use an IN or OUT instruction to read/write to the given pin.
