Southwest Specialty Products 6800 manual Special Notes on Using AN Acia and Program Modifications

NOTE: This does not mean that SWTBUG® is equipped with a binary loader-only certain SWTPC binary tapes that contain a special binary loader (in ASCII) will work correctly.

To load the tape simply follow the instructions given for loading an ASCII tape, but keep the reader locked on.

SPECIAL NOTES ON USING AN ACIA AND PROGRAM MODIFICATIONS

Many available 6800 programs written for MIKBUG® assume that a PIA type MP-C control interface is being used and may address this port directly. When using an ACIA type interface, these references need to be changed. For example, some programs, such as BASIC and CORES, poll the PIA periodically to see if a character has been typed in. This is done in order to kick out of a loop or a print sequence. (BASIC uses CTL..C. and CO-RES uses CTL..X.) The source statements that do this usually take the following form:

B6 8004	LDA A PIAD	LOAD A FROM DATA REG.
2B 03	BMI PRINT	BRANCH IF NOT CHAR. SEEN
7E XX XX	JMP READY or RESTART

PRINT REMAINDER OF SEQUENCE

To change to a MP-S serial interface, this code can sometimes be replaced as follows;

LDA A PIAD à	ASR A	SEE IF CHAR. LOADED
BMI PRINT à	BCS PRINT	BRANCH IF CHAR. INPUT
	JMP READY
	PRINT REMAINDER OF SEQUENCE

Before modifying any programs on your own, you should have a working knowledge of SWTBUG'S ACIA input routine, ACIA operation, and your particular program. The following is a list of patches to some SWTPC supplied programs.

BLKJAK - SWTPC 6800 Black Jack Program
LOCATION	DATA
0270	7E 064A
0647	7E	026D
064A	B6 E008
064D	27 08
064F	B6	8004
0652	2B F3
0654	7E	0275
0657	B6	8004
065A	47
065B	24EA
065D	20 F5

With the above modifications BLKJAK will be compatible with either an ACIA or PIA type interface.

CO-RES Ver. 1.0 and 1.01 ACIA Modifications

LOCATION	DATA
1682	47
1683	24 02
1685	20 A0

BASIC 8K and 4K up to an including Ver. 2.0 cannot be modified for ACIA operation. Later versions should be purchased.

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