From 6e035c864e06560d560ecaca4aeb019e156576e7 Mon Sep 17 00:00:00 2001
From: Colin Leroy-Mira <colin@colino.net>
Date: Thu, 12 Oct 2023 07:58:40 +0200
Subject: [PATCH] Apple2 SSC: on IIgs, verify slot mode
If the slot is not in "Your Card" mode, there's no way it is an SSC
---
libsrc/apple2/ser/a2.ssc.s | 112 ++++++++++++++-----------------------
1 file changed, 43 insertions(+), 69 deletions(-)
diff --git a/libsrc/apple2/ser/a2.ssc.s b/libsrc/apple2/ser/a2.ssc.s
index 82ac6690f..411c72dcd 100644
--- a/libsrc/apple2/ser/a2.ssc.s
+++ b/libsrc/apple2/ser/a2.ssc.s
@@ -25,8 +25,6 @@
.include "ser-kernel.inc"
.include "ser-error.inc"
- .importzp tmp1, tmp2
-
.macpack module
.macpack cpu
@@ -72,6 +70,8 @@ ACIA_STATUS := ACIA+1 ; Status register
ACIA_CMD := ACIA+2 ; Command register
ACIA_CTRL := ACIA+3 ; Control register
+SLTROMSEL := $C02D ; For Apple IIgs slot verification
+
;----------------------------------------------------------------------------
; Global variables
@@ -193,54 +193,35 @@ SER_CLOSE:
stx Index ; Mark port as closed
rts
-;----------------------------------------------------------------------------
-; Internal function to test whether we're really talking with a 6551,
-; or at least it really looks like it.
-; Input: X= Index
-; Output: carry set if this is very probably a 6551, clear if not
-
-Verify6551:
- lda ACIA_STATUS,x ; Save current values in what we expect to be
- pha ; the ACIA status register
- lda ACIA_CMD,x ; and command register. So we can restore them
- sta tmp1 ; if this isn't a 6551.
-
- and #$01
- bne NotAcia ; We expect command register bit 0 to be 0
-
- lda tmp1
- ora #$01 ; Enable receiver/transmitter
- sta ACIA_CMD,x
- sta tmp2 ; Store it for comparison
-
- lda ACIA_CMD,x ; Is command register what we wrote?
- cmp tmp2
- bne NotAcia
-
- sta ACIA_STATUS,x ; Reset Acia (value written is not important)
-
- lda ACIA_CMD,x ; Is the value back to the original value?
- cmp tmp1
- bne NotAcia
-
- pla ; Clear stack of leftovers
- clc
- rts
-
-NotAcia:
- lda tmp1 ; Restore saved bytes, they're probably needed
- sta ACIA_CMD,x
- pla
- sta ACIA_STATUS,x
- sec
- rts
-
;----------------------------------------------------------------------------
; SER_OPEN: A pointer to a ser_params structure is passed in ptr1.
; Must return an SER_ERR_xx code in a/x.
+; Note: Hardware checks are done in SER_OPEN instead of SER_INSTALL,
+; because they depend on the selected slot, and we can't select the slot
+; before SER_INSTALL.
SER_OPEN:
- ldx #<$C000
+ ; Check if this is a IIgs (Apple II Miscellaneous TechNote #7,
+ ; Apple II Family Identification)
+ sec
+ bit $C082
+ jsr $FE1F
+ bit $C080
+
+ bcs NotIIgs
+
+ ; We're on a IIgs. For every slot N, either bit N of $C02D is
+ ; 0 for the internal ROM, or 1 for "Your Card". Let's make sure
+ ; that slot N's bit is set to 1, otherwise, that can't be an SSC.
+
+ ldy Slot
+ lda SLTROMSEL
+: lsr
+ dey
+ bpl :- ; Shift until slot's bit ends in carry
+ bcc NoDev
+
+NotIIgs:ldx #<$C000
stx ptr2
lda #>$C000
ora Slot
@@ -249,8 +230,12 @@ SER_OPEN:
: ldy IdOfsTable,x ; Check Pascal 1.1 Firmware Protocol ID bytes
lda IdValTable,x
cmp (ptr2),y
- bne NoDev
- inx
+ beq ByteOK
+
+NoDev: lda #SER_ERR_NO_DEVICE
+ bne Out
+
+ByteOK: inx
cpx #IdTableLen
bcc :-
@@ -264,15 +249,16 @@ SER_OPEN:
.endif
tax
- jsr Verify6551
- bcs NoDev
-
; Check if the handshake setting is valid
ldy #SER_PARAMS::HANDSHAKE
lda (ptr1),y
cmp #SER_HS_HW ; This is all we support
- bne InvParm
+ beq HandshakeOK
+ lda #SER_ERR_INIT_FAILED
+ bne Out
+
+HandshakeOK:
ldy #$00 ; Initialize buffers
sty Stopped
sty RecvHead
@@ -289,9 +275,12 @@ SER_OPEN:
lda (ptr1),y ; Baudrate index
tay
lda BaudTable,y ; Get 6551 value
- bmi InvBaud ; Branch if rate not supported
- sta tmp1
+ bpl BaudOK ; Check that baudrate is supported
+ lda #SER_ERR_BAUD_UNAVAIL
+ bne Out
+
+BaudOK: sta tmp1
ldy #SER_PARAMS::DATABITS
lda (ptr1),y ; Databits index
tay
@@ -322,22 +311,7 @@ SER_OPEN:
; Done
stx Index ; Mark port as open
lda #SER_ERR_OK
- .assert SER_ERR_OK = 0, error
- tax
- rts
-
- ; Device (hardware) not found
-NoDev: lda #SER_ERR_NO_DEVICE
- ldx #$00 ; Promote char return value
- rts
-
- ; Invalid parameter
-InvParm:lda #SER_ERR_INIT_FAILED
- ldx #$00 ; Promote char return value
- rts
-
- ; Baud rate not available
-InvBaud:lda #SER_ERR_BAUD_UNAVAIL
+Out:
ldx #$00 ; Promote char return value
rts