This was a fantastic board when it first came out. It was at the time
when the IBM-PC was beginning to dominate the PC market and CPM 80/86
software was moving in mass to the PC-DOS platform. While many
manufactures could get their S-100 systems to be compatible on a text/disk
I/O basis with PC-DOS on the IBM-PC, what was absence was the ability to do
graphics and accept a true IBM-PC keyboard with an interrupt controller
etc.. Lomas (as I remember it anyway), were the first to address this
need with this board.
The board was densely packed with IC's but was easy to setup. The was
designed specifically to bring the wide range o£ software available for the
IBM-PC to the S-1OO bus. With this board and the appropriate software the
majority of software available for the IBM-PC including software that wrote
directly to video RAM and the hardware control ports of the IBM-PC could be
used with most high performance 8086 type CPU boards.
There are several issues in emulating the IBM-PC, the first is hardware
compatibility. The ma]or hardware items of the IBM-PC which must be
considered in an emulation are as follows:
1. The microprocessor being used.
2. The floppy disk controller hardware.
3. The display hardware.
4. The keyboard hardware.
5. The timer hardware.
6. The I/O hardware (i.e. RS232 and Printer ports etc.)
Each of these issues were addressed by LPD in the manual below.
The I/O ports of the board were assigned to correspond to the port
assignments of the IBM-PC for the corresponding functions.
The following is a list of device addresses on the COLOR MAGIC board:
|
Hex Adderss
|
Register Function
|
|
40
41
42
43
60
61
62
63
3D8
3D9
3DA
3DB
3DC
3D0-3D8
|
8253 TIMER 0
8253 TIMER 1
8253 TIMER 2
8253 TIMER CONTROL PORT
8255A PORT A
8255A PORT B
8255A PORT C
8255A COMMAND PORT
MODE CONTROL REGISTER
COLOR SELECT REGISTER
STATUS REGISTER
CLEAR LIGHT PEN LATCH
PRESET LIGHT PEN LATCH
6845 DISPLAY CONTROLLER REGISTERS
|
Through jumper selection the above ports could be relocated to any one of 64
different base addresses. When readdressed, IBM-PC compatibility was of
course lost. All port addresses are moved as a group and have an offset of
multiples of 400H added to the above address.
A fairly detailed manual was supplied. It can be
obtained
here.
The schematic for this board can be obtained
here.
