CS/A65 DUART

This Dual RS232 board uses two 16550A for the two interfaces. I know that there are ICs like the 16552(?) with two interfaces in one chip, but when I needed it, I had the parts at home already...

News:

2006-11-01 Added driver code.

Table of content

Driver

OS/A65 UART16550A driver

Board Revisions

1.0B (ok)

The driver consists of two files. First the uart16550.i65 file contains chip register definitions. The file ser_uart.a65 is the actual driver. This actually is a driver for a single UART only, but it can be linked into the system twice to handle both UARTs. The OS/A65 operating system (1.x and 2.x) uses a single entry point for the device, with the accumulator containing the command code. The entry point is prg1 in this case. It branches to these routines for the UART:

devini - initialize the UART
devirq - interrupt routine. This routine is called on every interrupt, one device after the other, until the irq is handled. The 50Hz system interrupt is last, so this driver uses this feature to check whether a new byte can be send at tx2.
others checks the other commands, like open, close, or handshake handling.

Unfortunately the driver code is pretty messy, but works.

	ser_uart.a65(Driver code)
	uart16550.i65(UART register definitions)

Board revisions

Version: 1.0B

Status: ok

Notes

This is the initial version.

Files

	csaduartdesc.txt
	csaduartparts.txt
	csaduart.ps.gz
	csaduart.png
	csaduart.fig
	csaduart.jpg(One of the UARTs is missing)