Atari 1040STE, Field Service Manual

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First the RS232 control lines are tested (which are tied together by the loopback
connector), the data loopback is tested. Data is checked transmittinglreceiving using
a polling method first, then using interrupts.
Data is transmitted at 300. 600, 1200...19200 bps. Data transmission is performed
by the MFP and the 1488 and 1489 driver and receiver chips. Interrupts are a
function of the MFP. Control lines are output by the PSG and input on the MFP. Note
that this test does not thoroughly test the drive capability of the port. If the unit
passes but fails in use, it is likely that the 1488 or 1489 chips are bad.
3.12.1 RS232 Error Codes
S0 Data Not Received. Check signal path, MFP pin 8 to J204 pin 2 via 1488 to
J204 pin 3 to MFP pin 9 via 1489.
S1 Data Mismatch. Data read was not what was sent. Check integrity of the
signal. May be bad driver, receiver, or MFP.
S2 Input Frame Error. Incorrect time between start and stop bits. Probable MFP
failure.
S3 Input Parity Error. Input data had incorrect parity. Probable MFP failure.
S4 Input Data Overrun. A byte was received before the CPU read the previous
byte. MFP failure.
S5 No IRQ. CPU did not detect an interrupt by the MFP. MFP or GSTMCU
failure.
S6 Transmit Error. MFP transmitter failed
.
S7 Transmit Error lnterrupt. An error condition was created intentionally to cause
an interrupt, and the MFP did not respond.
S8 Receive Error Interrupt. An error condition was created intentionally to cause
an interrupt, and the MFP did not respond.
S9 RI/DTR Connection. Signal sent at DTR is not detected at RI.
SA DCD/DTR Connection. Signal sent at DTR is not detected at DCD.
SB RTS/CTS Connection. Signal sent at RTS is not detected at CTS.
3.13 AUDIO TEST (A)
This test requires the operator to decide if the unit passes or fails.
There are two sound generating circuits: the Programmable Sound Generator (PSG)
and DMA sound. Both are controlled by the LMC1992 chip and associated circuitry,
so if the unit fails both parts of the test, look at the LMC1992 chip first.
3.13.1 PSG Sound
A sound is output on each of the three programmable sound generator channels.
The 518 sound is a sweep from low to high frequency. Verify that sound can be
heard throughout the range, with no dropping of audio level.