Cteni portu ISA

Jirka Netopil JNetopil
Středa Březen 17 11:49:08 CET 2004


Zkousel jsem cist i z jinych portuu, ale z ISA je to vzdy neco pres 500kHz a
z PCI neco pod 2HMz.
Jirka Netopil

> -----Original Message-----
> From: Slavomir Skopalik [mailto:skopalik@atlas.cz]
> Sent: Monday, November 20, 2000 9:29 AM
> To: Multiple recipients of list
> Subject: RE: Cteni portu ISA
>
>
> To je divne, nemate tam jeste nektera jina zarizeni ?
> Zkuste prosim treba SCSI adapter, nebo zvokuvku, pokud nemate
> video kartu.
> Proste jen ctete jeji port, dale zkuste cist port nejakeho
> PCI zarizeni.
> Predpokladam, ze vsechny testy provadite v dosu v Real modu CPU,
> pokud ne, nemusi to byt primo problem vaseho programu ci
> vaseho zarizeni.
>
>
> Slavek
> >
> > Jedna se o ISA kartu vlastni vyroby, ktera ihned po
> adresaci HW signalizuje
> > "zadne dalsi WaitStates".
> > Zkousel jsem ji nastavit na ruzne adresy (278h, 100h), ale
> stale z ni dokazu
> > cist pouze 500kHz.
> > Prolezl jsem cely SetUp, ale pro ISA se tam nenastavuje nic.
> > Jirka Netopil
> >
> > > -----Original Message-----
> > > From: Slavomir Skopalik [mailto:skopalik@atlas.cz]
> > > Sent: Thursday, November 16, 2000 12:37 PM
> > > To: Multiple recipients of list
> > > Subject: RE: Cteni portu ISA
> > >
> > >
> > > Ono taky zalezi na HW, co je na te ISE, zkuste cist napriklad
> > > z portu casovace (integrovane priferie),
> > > potom z portu ISA video karty a pak s pararelniho portu (o
> > > ten Vam asi jde).
> > > jinak jsem zkousel EPP a dostal jsem se na cca 0.5 - 1 MB/sec
> > > podle delky kabelu
> > > a schopnostem druheho konce (zarizeni). On totiz EPP (a asi i
> > > ECP) port ceka dokud
> > > zarizeni nepotvrdi prijem (nebo na time out).
> > >
> > > Slaek
> > >
> > > >
> > > > Nevite nekdo, proc nedokazu cist z portu na ISA smernici
> > > rychleji nez 500kHz
> > > > ?
> > > > Stejne je to z Windows i z DOSu (nabootovano do DOSu), na
> > > dvou ruznych
> > > > pocitacich (Pentium 100MHz a Duron 700MHz).
> > > > Podle nize uvedeneho by to melo jit rychlosti 2,7MHz (v
> > > 16-bit. rezimu - ten
> > > > moje karta pouziva).
> > > > Nameril jsem v 16-ti bitovem rezimu asi 500kHz a v 8-mi
> > > bitovem asi 330kHz.
> > > > Pouzivam nasledujici rutinu a merim cas, za jaky se to provede:
> > > > mov dx,PortNaISA
> > > > mov bx,1000
> > > > cli
> > > > sm1: mov cx,10000
> > > > sm2: in ax,dx
> > > > loop sm2
> > > > dec bx
> > > > jnz sm1
> > > > sti
> > > > Netusite nekdo, co delam spatne ? Jak to zrychlit ?
> > > > Jirka Netopil
> > > >
> > > > Speed:
> > > > Q: How can Parallel Port ISA card support quoted rates of
> > > data transfer in
> > > > excess of 1MB/sec ? As far a I know every in/out command
> > > for an ISA bus
> > > > address takes at least 1 microsecond to perform REGARDLESS
> > > of processor
> > > > speed ?
> > > > A: A simple parallel-port read or write does take one
> > > ISA-bus cycle, and on
> > > > most systems, the bus speed is around 1.3 Mhz, so one cycle
> > > is a little
> > > > under 1 microsecond. A complete data transfer on the
> > > original parallel port
> > > > usually takes at least 4 cycles, however: check the Busy
> > > status, write the
> > > > data, bring Strobe low, then high. On ports that support
> > > EPP and ECP modes,
> > > > in these modes the port hardware does the handshake, and a
> > > complete transfer
> > > > can take place in 1 bus cycle.
> > > > There are at least two ways of getting faster data
> > > transfers: Some ports
> > > > support a "fast mode" that uses the ISA bus's NOWS (no wait
> > > state) signal to
> > > > cause the CPU to skip 3 wait states. This mode is twice as
> > > fast, or around
> > > > 2.7 Mhz. ECPs also include hardware support for data
> > > decompressing (&
> > > > sometimes compressing, though that's often left for
> > > software), so the
> > > > effective rate of data transmission can be much faster than
> > > the number of
> > > > bytes written or read per second. Also, ECPs may be able to
> > > transfer data
> > > > between the host's and peripheral's ECP buffers at rates
> > > greater than 1 Mhz,
> > > > though the buffers are typically just 8 bytes.
> > > >
> > >
> >
>







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