The problems, that I was writing about lately, are caused by 4DOS' tinkering with Timer 0. Ed (DXForth creator) sent to me a little utility to check out; it's short Forth listing, but most is assembler:
#v+ \ Check current mode of the 8253/4 PC tick timer \ \ Compile with DX.EXE - INCLUDE GM.F BYE empty also forth definitions decimal application cr .( Compiling Getmode ) macro IODELAY $EB c, 0 c, endm \ jmp *+2 \ read Timer 0 count, result in BX label READTIMER pushf cli \ disable interrupts al al sub al $43 # out \ send command iodelay ( iodelay iodelay iodelay iodelay ) \ 1 $ ) call \ ** alternate delay method $40 # al in al bl mov \ get low byte iodelay ( iodelay iodelay iodelay iodelay ) \ 1 $ ) call \ ** alternate delay method $40 # al in al bh mov \ get high byte popf \ enable interrupts 1 $: ret end-code code GETMODE ( -- mode ) 3 # dx mov \ assume mode 3 500 # cx mov \ ** retries (Turbo-C uses 100) 1 $: cx dec 2 $ jcxz \ done, count always even = mode 3 readtimer ) call \ read current Timer 0 counter 1 # bx and \ test bit 0 1 $ jz \ loop if count even dx dec \ count was odd - must be mode 2 2 $: dx push \ return with mode on stack next end-code : GM ( -- ) dos-io cr ." Getmode" cr cr ." Getting PC tick timer mode (8253/54 Timer 0)" cr ." press any key to stop ..." cr begin getmode . 10 ms key? until key drop ; cr .( Save to disk? ) y/n [if] turnkey gm GM [then] cr cr .( Type GM to test ) cr #v- It's checking timer mode in a loop, displaying "2" or "3". When I ran it from command line: 1. When used 4DOS as a command shell, it's displaying both "2" and "3" in proportion about half-to-half. 2. When used FreeCon, it displayed only "3"s - and not a single "2". Watched its output about half a minute in both cases. Actually, why 4DOS is touching this timer at all? Does it really need to change mode of operation of Timer 0? Maybe something can be done different way, by not causing problems for programs/games, that are using this timer? -- Z. ------------------------------------------------------------------------------ Better than sec? Nothing is better than sec when it comes to monitoring Big Data applications. Try Boundary one-second resolution app monitoring today. Free. http://p.sf.net/sfu/Boundary-dev2dev _______________________________________________ Freedos-user mailing list Freedos-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/freedos-user
