Re: A86: linking w/ the 82

To: <assembly-86@lists.ticalc.org>
Subject: Re: A86: linking w/ the 82
From: "David Phillips" <electrum@tfs.net>
Date: Thu, 10 Dec 1998 16:09:31 -0600
Delivered-To: assembly-86-outgoing@towerguard.unix.edu.sollentuna.se
Reply-To: assembly-86@lists.ticalc.org


It appears that some are.  I don't understand how they were, but these are
the link port routines from the Vertigo source code.  From what I remember,
the byte to send/receive is in A, and the carry flag is set if there is an
error.  If someone wants to document these, that'd be awsome:

(note:  if you've ever seen the Vertigo source code, you'll know know it's
full of #ifdef's, #define's and #endif's, so I might have cut the wrong
code, left some out, etc...)

TryReceiveByte:
        in a,(LINKPORT)
        scf
        ret z
ReceiveByteCont:
        push bc
        ld b,_ASAP_RECCONT
        jr DoLink
ReceiveByte:
        push bc
        ld b,_ASAP_RECEIVE
        jr DoLink
SendByte:
        push bc
        ld b,_ASAP_SEND
DoLink:
        push de
        push hl
        ld hl,_ASAP_IND
        ld (hl),b
        ld hl,LinkErrorHandler
        call _setErrorHand
        set 2,(iy+12h)
        call _linkExec
        ld h,a
        call _clearErrorHand
        or 1            ;clear cf
.org $-1
LinkErrorHandler:
        scf
DoneLink:
        res 2,(iy+12h)  ;error handler resets this anyway
        ld a,h
        pop hl
        pop de
        pop bc
        ret

_setErrorHand   =41A1h
_clearErrorHand =41A4h
_ASAP_SEND      =0Ah
_ASAP_RECCONT   =14h
_ASAP_RECEIVE   =15h
_linkExec       =571Ch
LINKPORT        =7

>The protocol is documented, but there aren't any known ROM calls, or are
>there?

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