Using CP/M

CP/M Quick Reference 

Control key commands

CTRL + C	Restarts CP/M by initiating a warm start
CTRL + E	Forces the cursor to the next line of the screen for continued command line input.
CTRL + H	Moves the cursor one space to the left in the same manner as the BS key.
CTRL + I	Inputs a tab code (same as the TAB key)
CTRL + P	Turns on or off the printer echo function. When the printer echo function is turned on, data displayed on the LCD screen is output to the printer (or other device assigned to LST:) each time the RETURN key is pressed. The printer echo function is turned on by pressing CTRL + P once and is turned off when CTRL + P is pressed a second time. (Make sure the printer is connected properly before using this command.)
CTRL + R	Redisplays the contents of the current command line.
CTRL + S	Momentarily stops processing currently being performed (same as the PAUSE key). Processing can be resumed by inputting this command again.
CTRL + U	Cancels the current command line and moves the cursor to the next line on the screen for input of a different command.
CTRL + X	Erases the current command line and moves the cursor back to the beginning of the line.
CTRL + Z	Terminates input from the keyboard (used in combination with certain CP/M transient commands).

Commands

d: - A drive letter
filematch - an exact filename, or a wildcard match for files.
Items such as [item] are optional, ones such as <item> are compulsory.

DIR [d:][filematch]
Display a list of files in the specified, or current drive.

ERA [d:]<filematch>
Erase specified files. filematch *.* can be used to match all files in the current drive.

REN [d:]newname.ext = oldname.ext
Change the name of a disk file from oldname.ext to newname.ext

SAVE n [d:]filename.ext
Save the specified n number of pages of the transient program area to disk under the specified file name.

TYPE [d:]filename.ext
Display the contents of the specified file on the display screen. Display is only meaningful if the file contents was ASCII text.

USER n
Switches to the specified user area in a disk drive.
A user area is a physical area on a disk which has its own directory and which is managed separately from the rest of the disk. Data cannot be read from or written to any user area other than that in which CP/M is currently operating. A disk can be divided up into a maximum of 16 user areas.

PIP

Copy FOO.TXT to console (print).

C:PIP CON:=A:FOO.TXT

Write to file from terminal (CTRL-Z to EOF, CTRL-M+J for new line):

C:PIP FOO.TXT=CON:

Copy file from current drive to A:

C:PIP A:UPLOAD.COM=UPLOAD.COM

ED

• http://www.gaby.de/cpm/manuals/archive/cpm22htm/ch2.htm 
  

Commands mode

#a	load all lines from file (given as arg to the command) to memory
10a	load 10 lines from file
b#t	go to beginning, print all lines
b	go to beginning
n or -n	move n lines ahead/behind and print
t	print current line
k	kill current line
i	insert before current line
e	save and exit
o	discard changes

In insert mode

CTRL + H	backspace one char
CTRL + Z	exit insert mode

ASM

• http://www.gaby.de/cpm/manuals/archive/cpm22htm/ch3.htm#Section_3.6

Compile and run example program:

c:asm example
c:load example
example

Show compiled program listing:

type example.prn

Compiler output line markers

S	syntax error
L	bad label
E	bad expression
R	bad register
Y	bad value

API

• https://www.seasip.info/Cpm/bdos.html
• https://obsolescence.wixsite.com/obsolescence/cpm-internals
• http://www.gaby.de/cpm/manuals/archive/cpm22htm/ch5.htm
  

Entry point: 05h (CALL 05h).

Memory map

File Control Block

FCB start: 5Ch (not 60h as in the picture).

FCB       EQU  5Ch   ; File Control Block      
FCBFNAME  EQU  FCB+1 ; FCB File Name 

Address	Field	Definition
FCB+00h	dr	drive code (0-16) 0 = use default drive for file 1 = auto disk select drive A, 2 = auto disk select drive B,     ... 16 = auto disk select drive P.
FCB+01h	f1...f8	contain the filename in ASCII upper-case, with high bit = 0
FCB+09h	t1,t2,t3	contain the filetype in ASCII upper-case, with high bit = 0. t1', t2', and t3' denote the bit of these positions, t1' = 1 = Read-Only file, t2' = 1 = SYS file, no DIR list
FCB+0Ch	ex	contains the current extent number, normally set to 00 by the user, but in range 0-31 during file I/O
FCB+0Dh	s1	reserved for internal system use
FCB+0Eh	s2	reserved for internal system use, set to zero on call to OPEN, MAKE, SEARCH
FCB+0Fh	rc	record count for extent ex; takes on values from 0-127; Set this to 0 when opening a file
FCB+10h	d0...dn	filled in by CP/M; reserved for system use
FCB+20h	cr	current record to read or write in a sequential file operation; normally set to zero by user after opening file
FCB+21h	r0,r1,r2	optional random record number in the range 0- 65535, with overflow to r2, r0, r1 constitute a 16-bit value with low byte r0, and high byte r1

File Buffer start: 80h (128 bytes long).

Notes

When running command in CP/M with file path as first argument the drive number and file name are set in default FCB automatically before program runs. When two arguments are given another drive number and file name are set starting from absolute 6Ch. It will be overwritten by file operations. If no arguments are given the FCB file name is all blank/space characters ( ) Command line arguments are also available from 80h (File Buffer).

Useful constants:

FCB       EQU  5Ch     ; File Control Block
FCBFNAME  EQU  FCB+01h ; FCB File Name
FCBEX     EQU  FCB+0Ch ; FCB Excent Number
FCBRC     EQU  FCB+0Fh ; FCB Record Count
FCBCR     EQU  FCB+20h ; FCB Current Record
FB        EQU  80h     ; File Buffer

SelectedCP/M procedures

Function Number

Function
Name Input Output Dec Hex C0 Name0 DescriptionSystem Reset DEnone A (output)none 01h1 1 Console inputInput Wait for a character from the keyboard; then echo it to the screen and return it.none
A = ASCII char 03h2 Raw console input2 ReadsConsole a character from the console without checking for ^S / ^Q.
Output
E = char ASCIInone 09h3 Output string3 PrintReader string until $.Input pointer to stringnone
A = ASCII char 0Ah4 -4 BDOSPunch functionOutput E = char none 5 5 List Output E = char none 6 6 Direct Console I/O E = 0FFH (input) A = char E = 0FEH (status) A = status E = char none 7 7 Get I/O Byte none A = I/O byte value 8 8 Set I/O Byte E = I/O byte none 9 9 Print String DE = Buffer Address none 10 Buffered console inputA LineRead editorConsole String DE = Buffer Console characters in Buffer 11 B Get Console Status none A = 00/non zero 12 C Return Version # none HL = Version # 13 D Reset Disk System none none 14 E Select Disk E = Disk # none 15 F Open File DE = FCB address A = FF if not found 16 10 Close File DE = FCB address A = FF if not found 17 11 Search For First DE = FCB address A = Directory Code 18 12 Search For Next none A = Directory Code 19 13 Delete File DE = FCB address A = none 20 14 Read Sequential DE = FCB address A = Error Code 21 15 Write Sequential DE = FCB Address A = Error Code 22 16 Make File DE = FCB address A = FF if no DIR Space 23 17 Rename File DE = FCB address A = FF if not found 24 18 Return Login Vector none HL = Login Vector* 25 19 Return Current Disk none A = Current Disk Number 26 1A Set DMA Address DE = DMA address none 27 1B Get ADDR (ALLOC) none HL = ALLOC address* 28 1C Write Protect Disk none none 29 1D Get Read/only Vector none HL = ALLOC address* 30 1E Set File Attributes DE = FCB address A = none 31 1F Get ADDR (Disk Parms) none HL = DPB address 32 20 Set/Get User Code E = 0FFH for Get A = User Number E = 00 to 0FH for Set none 33 21 Read Random DE = FCB address A = Error 34 22 Write Random DE = FCB address A = Error Code 35 23 Compute File Size DE = FCB address r0, r1, r2 36 24 Set Random Record DE = FCB address r0, r1, r2 37 25 Reset Drive DE = Drive Vector A = 0 38 26 Access Drive not supported 39 27 Free Drive not supported 40 28 Write Random w/Fill DE = FCB A = error code

Reading file

Given file name in the arguments one can first check if argument was given by checking for space character in FCBFNAME (FBC + 01h).

If file name is used.filled Linewe outputcan open the file:

     XOR  A
     LD   (FCBEX),A   ; select 0'th extent
     LD   (FCBRC),A   ; clear
     LD   (FCBCR),A   ; clear
     LD   C,FOPE      ; open file
     LD   DE,FCB      ; use default FCB
     CALL BDOS

Set EX, RC and CR to 0 and call File Open (0Fh). A will contain FFh if file was not found.

Next file can be read:

     XOR  A
     LD   (FCBCR),A ; start from beginning
     LD   C,FRED    ; read file
     LD   DE,FCB    ; use default FCB
     CALL BDOS

Set CR to 0 to start reading from beginning of file and call Read Sequential (14h). A is writtenset startingto from0 2'ndif read was successful.

128 bytes was read to FB (80h). CR (and EX) will be automatically incremented, so calling Read Sequential again will read next 128 byte of the buffer. 0'th byte should be the length of the buffer, 1'st byte is ignored.

address or zero





file.