SIO help needed

[smp]

Hello all,

I have been experimenting with my Altair clone. I am trying to produce some code that will take input from the console keyboard and echo it verbatim out the second serial I/O port. This is a preamble to being able to have a program send output to some other display device while still having the console attached to my normal laptop running TerraTerm.

Anyway, I thought this would be an easy one to start with. I grabbed the source file for PCGET.ASM because I was going to strip out all the XMODEM stuff, and all I was really after was the proper way to initialize the Altair SIO ports.

Here is my code:

Code: Select all

;
                ;  SIO-EXPR - THIS PROGRAM TAKES INPUT FROM THE CONSOLE PORT
                ;  AND SENDS THE INPUT VERBATIM OUT SERIAL PORT B.
                ;
                ;  SERIAL PORT EQUATES
                
 0010 =         SIOACR	EQU	010H		;2SIO PORT A CONTROL REGISTER
 0011 =         SIOADR	EQU	011H		;2SIO PORT A DATA REGISTER
 0012 =         SIOBCR	EQU	012H		;2SIO PORT B CONTROL REGISTER
 0013 =         SIOBDR	EQU	013H		;2SIO PORT B DATA REGISTER
                
 0002 =         MODEM$SEND$MASK	EQU	2
 0002 =         SEND$READY	EQU	2	;VALUE WHEN READY
 0001 =         MODEM$RECV$MASK	EQU	1
 0001 =         RECV$READY	EQU	1	;BIT ON WHEN READY
                
                ;  TRANSFER RELATED EQUATES
                
 0001 =         SOH	EQU	1
 0004 =         EOT	EQU	4
 0006 =         ACK	EQU	6
 0015 =         NAK	EQU	15H
 0003 =         CTRLC	EQU	3			;CONTROL-C
 000A =         LF	EQU	10
 000D =         CR	EQU	13
                
 0100           	ORG	100H
                	
                ;  SWITCH TO LOCAL STACK AND DO THE TRANSFER
                
 0100 210000    DOXFER	LXI	H,0		;HL=0
 0103 39        	DAD	SP		;HL=STACK FROM CP/M
 0104 224702    	SHLD	STACK		;SAVE IT
 0107 314702    	LXI	SP,STACK	;SP=MY STACK
 010A CD4D01    	CALL	INIT$ACIA	;MASTER RESET THE ACIA
 010D 115A01    	LXI	D,MSEND		;POINT TO SIGN ON MESSAGE
 0110 0E09      	MVI	C,PRINT		;PRINT THE SEND MESSAGE
 0112 CD0500    	CALL	BDOS		;PRINT ID MESSAGE
                
 0115 CD2E01    LOOP	CALL	RECV
 0118 FE03      	CPI	CTRLC		;EXIT IF ABORT REQUESTED
 011A CA0602    	JZ	ABORT
 011D CD3F01    	CALL	SEND
 0120 C31501    	JMP	LOOP
                ;
                ; S U B R O U T I N E S
                ;
                ; - - - - - - - - - - - - - - -
                
                ;EXIT PRINTING MESSAGE FOLLOWING 'CALL ERXIT'
                
 0123 D1        ERXIT	POP	D		;GET MESSAGE
 0124 0E09      	MVI	C,PRINT
 0126 CD0500    	CALL	BDOS		;PRINT MESSAGE
 0129 2A4702    EXIT	LHLD	STACK		;GET ORIGINAL STACK
 012C F9        	SPHL			;RESTORE IT
 012D C9        	RET			;--EXIT-- TO CP/M
                
                ; - - - - - - - - - - - - - - -
                ;SIO RECV FROM CONSOLE
                ;-------------------------------------
 012E D5        RECV	PUSH	D		;SAVE
                
                ;  PORT A INPUT
                
 012F DB10      MWTI	IN	SIOACR
 0131 E601      	ANI	MODEM$RECV$MASK
 0133 FE01      	CPI	RECV$READY
 0135 CA3B01    	JZ	MCHAR		;GOT CHAR
 0138 C32F01    	JMP	MWTI
                
                ;  GOT AN INPUT FROM CONSOLE
                
 013B DB11      MCHAR	IN	SIOADR
 013D D1        	POP	D		;RESTORE DE
 013E C9        	RET
                
                ; - - - - - - - - - - - - - - -
                ;SIO SEND CHAR TO PORT B
                ;----------------------------------
                ;
 013F F5        SEND	PUSH	PSW		;SAVE THE OUTPUT CHARACTER
                
 0140 DB12      SENDWB	IN	SIOBCR
 0142 E602      	ANI	MODEM$SEND$MASK
 0144 FE02      	CPI	SEND$READY
 0146 C24001    	JNZ	SENDWB
 0149 F1        	POP	PSW		;GET CHAR
 014A D313      	OUT	SIOBDR
 014C C9        	RET
                
                ; INITITIALIZE THE SERIAL PORT
                
                INIT$ACIA:
                
                ; INITA - INIT PORT A
                
                ;	MVI	A,003H		;DON'T RESET CONSOLE PORT
                ;	OUT	SIOACR
 014D 3E15      	MVI	A,015H		;RTS ON, 8N1
 014F D310      	OUT	SIOACR
                
                ; INITB - INIT PORT B
                
 0151 3E03      INITB	MVI	A,3	
 0153 D312      	OUT	SIOBCR
 0155 3E15      	MVI	A,015H		;RTS ON, 8N1
 0157 D312      	OUT	SIOBCR
 0159 C9        	RET
                
 015A 0D0A4C4953MSEND	DB	CR,LF,'LISTENING ON CONSOLE PORT, SENDING TO PORT B...',CR,LF,LF,'$'
                
 018F 0D0A504347MHELP	DB	CR,LF,'PCGET VER 1.1',CR,LF,LF
 01A1 5553414745	DB	'USAGE: PCGET FILE.EXT [B]',CR,LF
 01BC 2020202020	DB	'       (B SPECIFIES 2SIO PORT B FOR TRANSFER)',CR,LF,'$'
                
                ;DONE - CLOSE UP SHOP
                
                XFER$CPLT:
 01EC CD2301    	CALL	ERXIT
 01EF 0D0A0A5452	DB	13,10,10,'TRANSFER COMPLETE',13,10,'$'
                
 0206 CD2301    ABORT:	CALL	ERXIT
 0209 0D0A0A5452	DB	13,10,10,'TRANSFER ABORTED',13,10,'$'
                
 021F           	DS	40	;STACK AREA
 0247           STACK	DS	2	;STACK POINTER
 0249           RSECTNO	DS	1	;RECEIVED SECTOR NUMBER
 024A           SECTNO	DS	1	;CURRENT SECTOR NUMBER 
 024B           FPORTB	DS	1	;FLAG TO USE 2SIO PORT B INSTEAD OF A
                ;
                ; BDOS EQUATES (VERSION 2)
                ;
 0001 =         RDCON	EQU	1
 0002 =         WRCON	EQU	2
 0009 =         PRINT	EQU	9
 000B =         CONST	EQU	11	;CONSOLE STAT
 000F =         OPEN	EQU	15	;0FFH=NOT FOUND
 0010 =         CLOSE	EQU	16	;   "	"
 0011 =         SRCHF	EQU	17	;   "	"
 0012 =         SRCHN	EQU	18	;   "	"
 0013 =         ERASE	EQU	19	;NO RET CODE
 0014 =         READ	EQU	20	;0=OK, 1=EOF
 0015 =         WRITE	EQU	21	;0=OK, 1=ERR, 2=?, 0FFH=NO DIR SPC
 0016 =         MAKE	EQU	22	;0FFH=BAD
 0017 =         REN	EQU	23	;0FFH=BAD
 001A =         STDMA	EQU	26
 0005 =         BDOS	EQU	5
 0000 =         REIPL	EQU	0
 005C =         FCB	EQU	5CH	;DEFAULT FCB
 005D =         PARAM1	EQU	FCB+1	;COMMAND LINE PARAMETER 1 IN FCB
 006D =         PARAM2	EQU	PARAM1+16	;COMMAND LINE PARAMETER 2
 024C           	END

You can see the LOOP in the middle there, simply a CALL RECV, check for CTRL-C, then CALL SEND.

You can also see the SIO initialization that is the pertinent pieces taken from the original PCGET.ASM.

You can also see that I have not fully stripped out a bunch of stuff left over from PCGET.ASM. That cleanup was to come later when I start to fill in whatever I come up with next.

None of this is a big deal, but it does not work!

When I have my two laptops hooked up, the console operates like it is supposed to, showing the LISTENING ON CONSOLE PORT, SENDING TO PORT B... message after I execute the program, then not showing any other keystrokes because they're being sent off to port B. Except, nothing shows up on my other laptop computer running Hyperterminal. When I type CTRL-C on the console, I properly get the TRANSFER ABORTED message, and the console returns to CP/M.

So, what's wrong with this picture? I am using tried and true cables, and both laptop computers function properly if I use them as my console device, so I am left wondering about my code. Can anyone take a look at the code and tell me if I have some obvious error? I do not have experience using an Altair 2-SIO board before. All my SIO experience is with more programmable devices such as the 8251 or the Z85C30 chip used on the SIO board from http://www.s100computers.com.

Thanks, in advance, for any suggestions that you may be able to make.

smp

[AltairClone]

The code looks reasonable.

Go into the Configuration Monitor under Serial Ports and verify that the second serial port in the Clone is configured as a 2SIO port (not SIO) at octal 22/23, 9600 baud and that CTS and RTS are not used.

Mike

[smp]

OK! That did the trick. Port B was set as an SIO, not the 2-SIO.

Thanks a million for your help, Mike.

So now, here's my next question:

I noticed that the code I posted was calling the SIO ports as 10 & 11 and 12 & 13. So, I changed the code to call them 20 & 21 and 22 & 23. Then I saw the comment marks in the code for not doing a reset on the console port, so I went further and commented out all the ACIA setup, assuming that it would already be there from the system setup.

Wrong! That code did not work at all.

So, I put the code back to calling the SIO ports 10 & 11 and 12 & 13, and I un-commented the setup byte for port A (as it was before) and I took the comment marks off of the port B code (as it was before), and I am back to working again.

I thought that the ports would be all set up by the system initialization so I wouldn't actually have to do anything, but that was not so. Now I am looking at code that talks to the wrong port locations, but the code works...

I am all confused.

smp

[AltairClone]

The Clone menus use the MITS convention of octal for the port addresses. The code you are using is using hex constants. For example, port 20 in octal is the same as port 10 expressed in hex.

The ACIA reset for port 10 was commented out in the code because CP/M already initialized the console serial port during cold boot. The 2nd port at 12 hex is not initialized by CP/M, so the code must do it.

Mike

[smp]

Hi again, Mike,

YIKES! I am embarrassed, for sure.

The same binary bit pattern but differing representations caught me, big time.

Thank you very much for your patient explanation. I was really stuck on this silly misinterpretation.

Thanks also for the explanation that Port B is not set up by CP/M. I should have figured that one out, too.

smp