Service manual

Chapter 4 E01 Circuit description
FileStore Service Manual 24
OSBYTE
The following OSBYTE functions are supported:
A=50 POLL TRANSMIT – as BBC
A=51 POLL RECEIVE – as BBC
A=52 Delete RECEIVE – as BBC
A=128 X=0: Read COMMAND/ USER and Floppy drive door switch states, returns 2
if drive 2 open, 1 if in COMMAND mode
X=252: Read free bytes in printer output buffer.
A=132 Read address of top of workspace area to X/Y. The value returned is the
current base of the MOS.
A=l37 LED control. X=0 will turn off the programmable led, X=1 will turn it on.
4.14 Link survey
Link functions are as follows:
LINK Function
1 I/O IRQs on/off (made = on)
2 A15 addressing on/off (made = on)
3 1us. Net clock enable
4 2us net clock enable
5 Net clock divide by 2 enable
6 Net clock divide by 4 enable
7 Net clock divide by 8 enable
8 Net NMIs enable/ disable (made = enable)
9 0 to &7FFF addressing disable (unmade = enable)
10 Rom latch enabled/ disabled (made = enabled)