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BUILD

You'll need

INSTALL

Burn either 27c512.hex, 27c256.hex, 27c128.hex or 27c64.hex to your EPROM chip.

USE

CP/M disk format

CBIOS expects CF card to be formatted with MBR using LBR addressing and up to 4 primary partions of type 52h and size up to 8MB each. First 'track' of a partiotion is sytem track, put CCP+BDOS there, so CP/M can boot. You can access filesystem on these partitions or partition images from PC using either

cpmtools-compatible disk definition:

diskdef pac80
  seclen 512
  tracks 1024
  sectrk 16
  blocksize 8192
  maxdir 512
  skew 0
  boottrk 1
  os 2.2
end

MEMORY MAP

256K memory space is divided to 16 16KB-pages. 64KB CPU address space is divided to 4 16KB-banks. Each bank can be mapped to any page. After reset all banks are mapped to page f. Video memory starts at 1810h offset in each video page/plane. Column 0 at 1810h-18ffh, column 1 at 1910h-19ffh, and so on, total 40 columns. Plane 0 color is navy blue, plane 1 color is sand, both planes together give white.

Page Type Notes
0 RAM
1 RAM
2 RAM
3 RAM
4 RAM video page 0 plane 0 at 1810-3fff
5 RAM video page 0 plane 1 at 1810-3fff
6 RAM video page 1 plane 0 at 1810-3fff
7 RAM video page 1 plane 1 at 1810-3fff
8 RAM optional
9 RAM optional
a RAM optional
b RAM optional
c RAM optional
d RAM optional
e RAM optional
f ROM

I/O PORTS

Port Assigned to
00-07 EXT0
10-17 EXT1
20-27 EXT2
30-37 CF
08 BANK0
48 BANK1
88 BANK2
c8 BANK3
1a PPI PORT A
1b PPI PORT B (SEL=1)
19 PPI PORT B (SEL=0)
1c PPI PORT C
1d PPI CONTROL
28 UART DATA
29 UART CONTROL/STATUS
38 PSG

8255 ports

Function SEL=0 SEL=1 2nd 0 2nd 1 3rd 0 3rd 1 4th 0 4th 1
PB0 gamepad UP UP UP UP 0 Z 1 UP
PB1 gamepad DOWN DOWN DOWN DOWN 0 Y 1 DOWN
PB2 gamepad 0 LEFT 0 LEFT 0 X 1 LEFT
PB3 gamepad 0 RIGHT 0 RIGHT 0 MODE 1 RIGHT
PB4 gamepad A B A B A B A B
PB5 gamepad START C START C START C START C
PB6 gamepad 0 1 0 1 0 1 0 1
PB7 always=1 1 1 1 1 1 1 1 1
WRITE READ
PC0 video page video page
PC1 VBLANK interrupt enable VBLANK interrupt enable
PC2 UART interrupt enable UART interrupt enable
PC3 keyboard interrupt request
PC4 keyboard interrupt enable keyboard strobe
PC5 keyboard input buffer full
PC6 VBLANK interrupt request
PC7 UART interrupt request