Cteni portu ISA

[Jirka Netopil]

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.
> >
>