MCS-4 Micro-Lab Software

Software Description.

The first issue in developing the software for this system was exactly how
to write it. There are obviously no development packages around for the
MCS-4 family. A search on the Web produced little in the way of development
tools. The initial code that I wrote was all hand assembled - just like
the old days. I soon realized that this would be way too cumbersome once
the code got to be more than a few hundred bytes in size. I also wanted to
be able to relocate routines and use labels for addresses. The solution to
this problem was to write my own assembler.

My assembler is written in 'C' and uses a two pass assembly method to
resolve labels. It allows code to be relocated via an "ORG" directive and
will produce both a list file and an Intel Hex format file for EPROM
programming. The assembler is hosted on the PC (DOS) but is easily portable
to any other environment.

Below is an example of the list file produced by the assembler:

                   ROM  0800
                   ORG  0000
0000 START:
0000  51                JMS  REG-INIT
0001  6A
0002  55                JMS  PMEM-INIT
0003  4C
0004  51                JMS  DISP-INIT
0005  8E
0006  2C                FIM  RC,RD,#60
0007  60
0008  2D                SRC  RC,RD
0009  D0                LDM  #0
000A  E2                WRR
000B  6C                INC  RC
000C  2D                SRC  RC,RD
000D  E2                WRR
000E  BA                XCH  RA
000F  20                FIM  R0,R1,&STARTUP-MSG
0010  D5
0011  57                JMS  WRITE-MSG
0012  16
0013 MAIN-LOOP:
0013  51                JMS  RD-KB           ;RA=KEY, RB=BANK
0014  00
0015  AB                LD   RB
0016  14                JCN  A0,MAIN-LOOP    ;WAIT FOR FN KEY
0017  13