Redirecting LST to CRT?

[pawosm-arm]

I have some programs which send MIDI commands to LST:, and a custom serial terminal program which can detect and filter out MIDI commands from the console communication and forward them to a MIDI synth. Sadly, when I redirect LST: to CRT (by invoking device lst:=crt), things sent to LST: seem to get malformed before they reach serial console, i.e. nothing is forwarded to MIDI synth and some garbage is printed on the console. Is there something CRT does that makes it unusable as LST: device?

EDIT: I was wrong, Z80-MBC2 does it correctly, it was my omission of required params when starting this sophisticated terminal program.

[Ho-Ro]

O>device lst:=crt     

Physical Devices: 
I=Input,O=Output,S=Serial,X=Xon-Xoff
CRT    NONE  IO     LPT    NONE  O      SIOA   NONE  IOS    SIOB   19200 IOS    

Current Assignments: 
CONIN:  = CRT    
CONOUT: = CRT    
AUXIN:  = SIOA   
AUXOUT: = SIOA   
LST:    = CRT    


O>pip lst:=a:abc75.txt
ABCDEFGHIJKLMNOPQRSTUVWXYABCDEFGHIJKLMNOPQRSTUVWXYABCDEFGHIJKLMNOPQRSTUVWXY
O>type a:abc75.txt
ABCDEFGHIJKLMNOPQRSTUVWXYABCDEFGHIJKLMNOPQRSTUVWXYABCDEFGHIJKLMNOPQRSTUVWXY

It works for 7bit data 0x00..0x7F, but MIDI Statusbytes have bit 7 set 0x80..0xFF.
You can set the CRT to 8 bit mode via SYSFLAG, this was introduced for XMODEM -> BIOS src code CHARIO.MAC

; 
;<<<<<<<<<<<<<<<<<<< MAIN CONSOLE/DEVICE 0 STATUS ROUTINE (Z80-MBC2) >>>>>>>>>>>>>>>>>>>
;


cist0:				; DEVICE 0 INPUT STATUS
	ld	a,(?cnstflg)	; A = CONST mode flag
	or	a		; CONST mode flag = 0?
	jr	z,const7	; Yes, jump to 7 bit CONST routine
const8:				; No, 8 bit mode CONST routine
	ld	a, sysflag$opc	; A = SYSFLAG opcode
	out	(sto$opcd),a	; Write the opcode
	in	a,(exc$rd$opcd)	; Read SYSFLAG data into A
	and	04h		; Rx serial buffer empty (D2 = 0)?
	jr	z,noinchr	; Yes, jump
				; No, set char ready flag

inchr:				; Set char ready flag
	ld	a, 0ffh		; Return CP/M a char ready flag ($FF)
	ret

const7:
	ld	a,(inchrbuf)	; A = previous char read by CONST, if any
	cp	0ffh		; Is = $FF ($FF from UART = no char)?
	jr	nz,inchr	; No, jump (char already read and ready)
	in	a,(serial$rx)	; Yes, Read a char from "virtual" UART
	ld	(inchrbuf),a	; Store it
	cp	0ffh		; Is = $FF ($FF from UART = no char)?
	jr	nz,inchr	; No, set char ready flag
				; Yes, set char not ready flag

noinchr:			; Set char not ready flag
	xor	a		; Set no char flag (A = 0)
	ret			; Return CP/M no char flag ($00)
	
inchrbuf:
				; Last read char by CONST ($FF = no char)
	defb	0ffh		; Initialized as $FF
?cnstflg:
	defb	0h		; CONST mode flag. If = 1 the full 8 bit mode is ac
				; if = 0 the "legacy" 7 bit mode is used (not really 7 bit
				; but only the $ff char is ignored and used as "no char" flag ***

cost0:				; DEVICE 0 OUTPUT STATUS (Z80-MBC2) 
	ld	a, 0ffh		; Always ready to TX
	ret

;
;<<<<<<<<<<<<<<<<<<<< MAIN CONSOLE/DEVICE 0 INPUT ROUTINE (Z80-MBC2) >>>>>>>>>>>>>>>>>>>
;

[pawosm-arm]

Thanks for sharing this. What is the easiest way of setting this SYSFLAG?

[Ho-Ro]

It's done with a BIOS call - unofficial number 0x5A
set 8 bit CONST mode (non standard jmp. Z80-MBC2)

Below is the example code from XMODEM29 with Z80-MBX2 enhancements:

;**************
; CP/M Equates
;**************
;------------------------------------------
;BDOS Entry Points and low-memory locations
;------------------------------------------
wboot	equ	0000h		; Jump to BIOS warm boot
wboota	equ	wboot+1		; Address of Warm Boot

; ...

;--------------------------------------------
;BIOS Entry Points, relative to the base
;address in WBOOT. BIOS calls are used
;(instead of BDOS calls) where speed matters.
;--------------------------------------------
const	equ	06h		; Console Status
conin	equ	09h		; Console Input
conout	equ	0ch		; Console output
punch	equ	12h		; Punch output
reader	equ	15h		; Reader input
constmd	equ	5ah		; Z80-MBC2 set CONST mode to 8-bit

; ... 
	; Set the CONST mode to 8-bit mode on the Z80-MBC2
	ld	a,constmd
	call	gobios
; ...

;***Subroutine*********************
;Go call a BIOS driver directly
;On Entry:
;  c=value for BIOS routine, if any
;  a = BIOS call address offset
;On Return:
;  psw as BIOS left it
;  all other regs preserved
;(116 cycles + BIOS time)
;**********************************
gobios:	push	hl		; (11)
	push	de		; (11)
	push	bc		; (11)

	call	dobios		; (17+26+BIOS time)

	pop	bc		; (10)
	pop	de		; (10)
	pop	hl		; (10)
	ret			; (10)

;---Local Subroutine---------------
;Go call a BIOS driver directly
;On Entry:
;  c=value for BIOS routine, if any
;  a = BIOS call address offset
;On Return:
;  all regs as BIOS left them
;(26 cycles + BIOS time)
;----------------------------------
dobios:	ld	hl,(wboota)	; (16)get BIOS base address
	ld	l,a		; (5)a has jump vector

	jp	(hl)		; (5) 'call' BIOS routine

Warmboot resets to 7 bit CONST.

HTH, Martin

Ohterwise -> @SuperFabius is the master of Z80-MBC2

[pawosm-arm]

I've tried to use BDOS function which calls BIOS, but it only dumped some trash on the console and hung:

#include <stdint.h>
#include <cpm.h>
#include <cpm/bdos.h>

int main()
{
  uint8_t bios_params[8U] = {
    0x5aU, /* unofficial constmd function */
    0U,    /* A */
    0U,    /* C */
    0U,    /* B */
    0U,    /* E */
    0U,    /* D */
    0U,    /* L */
    0U     /* H */
  };

  _bdos(BDOS_S_BIOS, ((uint16_t)(bios_params)));
  return 0;
}

Shouldnt' this 0x5a function receive any parameters through the registers?

[pawosm-arm]

Ok, this wouldn't work. I didn't notice you saying Warmboot resets to 7 bit CONST.. What I'd rather need would be something like this:

#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <cpm.h>
#include <cpm/bdos.h>

#define MAX_PARAMS 8U

typedef char *char_p;

int main(int argc, char **argv)
{
  int i;
  char_p args[MAX_PARAMS +  1U];
  uint8_t bios_params[8U] = {
    0x5AU, /* unofficial constmd function */
    0U,    /* A */
    0U,    /* C */
    0U,    /* B */
    0U,    /* E */
    0U,    /* D */
    0U,    /* L */
    0U     /* H */
  };

  _bdos(BDOS_S_BIOS, ((uint16_t)(bios_params)));
  if (1 < argc) {
    if (MAX_PARAMS < argc)
      abort();
    for (i = 0; i < (argc - 2); i++)
      args[i] = argv[2 + i];
    args[i] = NULL;
    execv(argv[1], args[0] ? args : NULL);
    abort();
  }
  return 0;
}

...but it doesn't work. And it doesn't have to! Finally I've realized that I'm starting this terminal program wrong way! Somehow I omitted the param which actually turns the MIDI feature ON, and all the MIDI codes were dumped on screen. Turns on, Z80-MBC2 does what it needs to do by default!

I'm sorry for the mess, nevertheless it was fun hearing it play MIDI tunes in the end :)