Unconventional spare memory

&90-&96 Unused Econet workspace

&236/7 Address of OS variables, =&0190
&238/9 Address of extended vectors, =&0D9F, read by many programs
&23A/B Address of ROM table, =&02A1 or =&02A0, read by many programs
&23C/D Address of keyboard translation table, =various
Internationalisation ROMs uses these
&23E/F Address of VDU variables, =&0300

&240 CFS timeout, decrements continuously every 1/50 sec
CFS writes to time inter-block gaps

&249 Palette RAM copy - irrelevant as 16 palette entries, nothing relevant
to read. Written to by VDU 19. Electron ROM polling semaphore.

&25E only b7 checked, b0-b6 free, *REMOTE sets bit 7, *ROFF clears bit 7
&25F only b7 checked, b0-b6 free, *REMOTE sets bit 7, *ROFF clears bit 7
&260 only b7 checked, b0-b6 free, *REMOTE sets bit 7, *ROFF clears bit 7

&267 b7/b0 used, b1-b6 free and not modified. Is modified with INC/DEC, so
b1 needs to be left clear as an overflow
Master uses DEC/INC so b1-b6 will be toggled during ROMFS */!BOOT

&800-&803


Spare memory in MOS 120
Speech system uses:
DB11-DB26  22 bytes Initialise Speech timer
DD6F-DDC9  91 bytes Speech IRQ
DE1A-DE2A  17 bytes Speech timer
E830-E833   4 bytes SOUND &FFxx branch
E88D-E8A3  23 bytes Insert Speech into buffer
EE20-EE50  49 bytes Speech ROM access
EE62-EEAC  75 bytes Speech hardware access
EEBB-EED9  31 bytes Speech hardware access


MOS HELP code:

.loop
INX:LDA helptxt,X:BEQ done:BMI token
JSR OSWRCH:JMP loop
.token
TAY
.token_loop
LDA helptxt-&80,Y:BEQ loop
JSR OSWRCH:INY:BNE token_loop
.done
JSR OSNEWL

.helptxt
EQUS "<a>(,":EQUB hlpXY-helptxt+&80:EQUB 0 :\ FX    <a>(,<x>(,<y>))
EQUB 0                                     :\ BASIC
EQUS "(<path>)":EQUB 0                     :\ CAT   (<path>)
EQUS "(":EQUB hlpXY-helptxt+&80:EQUB 0     :\ CODE  (<x>(,<y>))
EQUS "(":EQUB hlpFILE-helptxt+&80:EQUS ")" :\ EXEC  (<file>)
EQUS :text:                                :\ HELP  (<text>)
EQUS "<key> ":text:                        :\ KEY   <key> (<text>)
EQUS :file:" ":load:                       :\ LOAD  <file> (<load>)
EQUS :text:                                :\ LINE  (<text>)
EQUS "(":XY                                :\ MOTOR (<x>(,<y>))
EQUS "(":XY                                :\ OPT   (<x>(,<y>))
EQUS :file:" ":text:                       :\ RUN   <file> (<text>)
EQUS ""                                    :\ ROM
EQUS :file:" <start> <end>|+<length> (<exec> ":load:")"
EQUS :file:                                :\ SPOOL <file>
EQUS "<speed>"                             :\ TAPE  <speed>
EQUS "(":XY                                :\ TV    (<x>(,<y>))
etc
.hlpXY  :EQUS "<x>(,<y>))":EQUB 0
.hlpFILE:EQUS "<file>":EQUB 0
.hlpTEXT:EQUS "(<text>)":EQUB 0
.hlpLOAD:EQUS "(<load>)":EQUB 0