Service manual

Chapter 5 E01S Fault finding
FileStore Service Manual 73
&FFE3 OSASCI entry
&FFE7 OSNEWL entry
&FFEE OSWRCH entry
&FFF1 OSWORD entry
&FFF4 OSBYTE entry
&FFFA NMI vector
&FFFC RST vector
&FFFE IRQ vector
Page zero is suballocated as follows:
From To Function
&00 &1F Spare (some locations used if debug options enabled in
MOS)
&20 &8F File server/print server workspace
&90 &9F Spare at present, but may be allocated to file server
&A0 &AF Econet driver workspace
&B0 &BF File server workspace
&C0 &DF Econet driver workspace
&E0 &FF Disc handler workspace
Page &FC (the memory mapped I/O page) is suballocated as follows:
&FC00[-&FC03] 146818 RTC address register
&FC04[-&FC07] 146818 RTC data register
&FC08[-&FC0B] (read) ROM/RAM memory access lamb (currently will
always select RAM).
&FC08[-&FC0B] (write) miscellaneous function latch
&FC0C-&FC0F 2793 Floppy Disc Controller
&FC10-&FC1F 6522 Versatile Interface Adaptor
&FC20-&FC23 6854 Econet interface
&FC24[-&FC27] Econet interrupt disable
&FC28[-&FC2B] Econet interrupt enable
&FC2C[-&FC2F] Floppy drive door switch state
&FC30-&FC33 FileStore expansion bus interface. Strapped to emulate
bus address &40, the bottom two bits of the &FC3x
address indicate bus &4x.
Higher values in this page will access the same registers as above if taken modulo &40.
Values in square brackets above are also alternate addresses for the various registers. Note
that addresses are subject to change, and this should be borne in mind when designing
software to address these registers.
4.10.4 Machine Operating System function calls
The file server MOS provides a subset of the BBC MOS interface. It is not necessarily the
case that any test programs running in place of the file server will be able to obtain all the
desired support from the MOS. Such test programs should however be written with an
awareness of the MOS in mind. In particular, it is recommended that the contents of hardware
registers and interrupt vectors are saved and restored over the execution of a test program,
and the stack pointer restored to its value on entry.
The file server MOS provides the following functions, at the standard addresses:
OSASCI, OSNEWL, OSWRCH