CP/M 3.0 BIOS
Here is a CP/M 3.0 BIOS
implementation for the P112. It has the following features:
- Support for Banked and Non-Banked operation.
- 60K TPA with Banked BIOS.
- Support for two floppy drives.
- Support for GIDE hard disks, up to four partitions.
- RAM disk created out of the remaining available memory.
- Real-time clock interrupts, used for keeping the Time-Of-Day and for
controlling the floppy drive motors.
- The Time-Of-Day routines use the hardware CMOS clock.
The BIOS follows the modular structure recommended by the Digital Research
documentation. Here is a list of the modules with their corresponding
file names:
- Floppy disk: FDIO.MAC
Most of the code for the floppy disk module was taken from the original P112
BIOS for CP/M 2.2, with the enhancements made by Hal Bower. Therefore, the
system recognizes the same variety of floppy drives and formats the previous
BIOS did.
- Hard disk: HDIO.MAC
Currently, only the GIDE interface is supported. Up to four partitions
are automatically recognized (see the FDISK
program), each one up to 32 Mbytes in size. All partitions are assumed
to have the same characteristics (4K block size, 2048 directory entries,
2 reserved tracks).
- RAM disk: RAMDISK.MAC
Automatically creates a drive M: from the remaining available memory.
- Character I/O: CHARIO.MAC
Three devices are defined: COM1, COM2 and LPT, corresponding to the first
and second serial interfaces and the parallel port of the P112,
respectively. The serial devices support baud rate change by software (e.g.
by using the DEVICE command), and both are initialized to the value stored
in the DS1202 NV RAM. COM1 divisor values assume a 16MHz CPU.
- Root module: BIOSKRNL.MAC
This is the invariant portion of the BIOS and contains only a minimal
set of changes from the original Digital Research's version.
- Cold/Warm boot loader module: BOOT.MAC
The main setup is done here: initial device assignment, the Z180
MMU and interrupt initialization routines are called,
CCP.COM is reloaded and the sign-on message is displayed.
- Drive table definition: DRVTBL.MAC
Which disk drive corresponds to which letter can be found here. Normally,
the first two floppies are assigned to A and B, the first GIDE partition
is C, the second D, etc. and the RAM-disk is M.
- P112-specific functions: MISC.MAC
Z180 MMU, interrupt and programmable timer initialization; interrupt
handling, etc.
- Intra/Inter-bank moves: MOVE.MAC
- System Control Block definitions: SCB.MAC
- Real-time clock support: TIME.MAC
DS-1202/1302 access routines and date/time conversion routines.
This BIOS can also be used with ZPM3 and ZCCP, except that you will
not be able to boot from a GIDE partition (e.g. drive C): for some
reason, ZCCP always looks for ZINSTAL.ZPM in drive A, so booting from a
different drive will not work. Booting ZPM3/ZCCP from A: works fine,
though.
Compiling the system
There are two SUBMIT files included in the distribution that you can use
to build the BIOS:
BIOS.SUB - builds a non-banked version.
BNKBIOS.SUB - builds a banked version.
The SUBMIT files assume that you have Microsoft's M80 and Digital Research's
LINK on the same disk. Both command files call GENCPM at the end of
compilation.
Example of banked system generation:
C>gencpm
CP/M 3.0 System Generation
Copyright (C) 1982, Digital Research
Default entries are shown in (parens).
Default base is Hex, precede entry with # for decimal
Use GENCPM.DAT for defaults (Y) ?
Create a new GENCPM.DAT file (N) ?
Display Load Map at Cold Boot (Y) ?
Number of console columns (#80) ?
Number of lines in console page (#24) ?
Backspace echoes erased character (N) ?
Rubout echoes erased character (Y) ?
Initial default drive (C:) ?
Top page of memory (FF) ?
Bank switched memory (Y) ?
Common memory base page (C0) ?
Long error messages (Y) ?
Accept new system definition (Y) ?
Setting up Checksum vector for drive A:
Setting up Checksum vector for drive B:
*** Bank 1 and Common are not included ***
*** in the memory segment table. ***
Number of memory segments (#2) ?
CP/M 3 Base,size,bank (7F,41,00)
Enter memory segment table:
Base,size,bank (00,7F,00) ?
Base,size,bank (00,C0,02) ?
CP/M 3 Sys 7F00H 4100H Bank 00
Memseg No. 00 0000H 7F00H Bank 00
Memseg No. 01 0000H C000H Bank 02
Accept new memory segment table entries (Y) ?
Setting up directory hash tables:
Enable hashing for drive A: (N) ?
Enable hashing for drive B: (N) ?
Enable hashing for drive C: (N) ?
Setting up Blocking/Deblocking buffers:
The physical record size is 0400H:
Available space in 256 byte pages:
TPA = 00F1H, Bank 0 = 007FH, Other banks = 00C0H
Number of directory buffers for drive A: (#1) ?
Available space in 256 byte pages:
TPA = 00F1H, Bank 0 = 007AH, Other banks = 00C0H
Number of data buffers for drive A: (#4) ?
Allocate buffers outside of Common (Y) ?
Available space in 256 byte pages:
TPA = 00F1H, Bank 0 = 007AH, Other banks = 00B0H
Number of directory buffers for drive B: (#1) ?
Available space in 256 byte pages:
TPA = 00F1H, Bank 0 = 0076H, Other banks = 00B0H
Number of data buffers for drive B: (#4) ?
Allocate buffers outside of Common (Y) ?
The physical record size is 0200H:
Available space in 256 byte pages:
TPA = 00F1H, Bank 0 = 0076H, Other banks = 00A0H
Number of directory buffers for drive C: (#1) ?
Available space in 256 byte pages:
TPA = 00F1H, Bank 0 = 0074H, Other banks = 00A0H
Number of data buffers for drive C: (#4) ?
Allocate buffers outside of Common (Y) ?
The physical record size is 0080H:
Available space in 256 byte pages:
TPA = 00F1H, Bank 0 = 0074H, Other banks = 0098H
Number of directory buffers for drive M: (#1) ?
Available space in 256 byte pages:
TPA = 00F1H, Bank 0 = 0073H, Other banks = 0098H
Accept new buffer definitions (Y) ?
BNKBIOS3 SPR F700H 0900H
BNKBIOS3 SPR AC00H 1400H
RESBDOS3 SPR F100H 0600H
BNKBDOS3 SPR 7E00H 2E00H
*** CP/M 3.0 SYSTEM GENERATION DONE ***
C>
The initial device assignment is:
CON: = COM1:
AUX: = COM2:
LST: = LPT:
and the disk assignment:
A: = first floppy drive
B: = second floppy drive
C: = first CP/M partition found
D: = second CP/M partition found
E: = third CP/M partition found
F: = fourth CP/M partition found
M: = RAM disk
Installing CP/M 3.0 on a hard disk partition
General steps:
- Create the partition with FDISK, if you
haven't yet done so. Set the type to CP/M 3.0, and flag it as bootable.
- Boot CP/M 3 from a floppy or from another HD partition, and make sure
the new partition is recognized (note the drive letter).
- Initialize the partition (erase the directory with the supplied ERADIR
utility).
- Create HCPMLDR.BIN from the LDRHD.ASM and CPMLDR.REL files:
M80 =LDRHD.ASM
LINK HCPMLDR.BIN=CPMLDR,LDRHD[OC,L100]
- Compile HDBOOT.BIN:
M80 =HDBOOT
LINK HDBOOT.BIN=HDBOOT[NR,OC,L0]
- Use e.g. DDTZ to create a boot track image by combining HDBOOT.BIN and
HCPMLDR.BIN, the last should be loaded at relative offset 200h (L200
command below). Update the checksum byte of the boot loader before saving:
A>DDTZ
DDTZ v2.7M by CB Falconer. CPU=Z80
-F100,7FFF,0
-NHDBOOT.BIN
-L
Next PC Save
0280 0100 2
-NHCPMLDR.BIN
-L200
Next PC Save
1880 0100 24
-A8000
8000 LXI H,100
8003 LXI D,1FF
8006 XRA A
8007 ADD M
8008 INX H
8009 DCX D
800A MOV C,A
800B MOV A,D
800C ORA E
800D MOV A,C
800E JNZ 8007
8011 CMA
8012 INR A
8013 MOV M,A
8014 RST 7
8015 .
-G8000
*8017
C0Z0M0E0I0 A=36 B=00CA D=0000 H=02FF>3136 S=EBF5>E410 P=8015 NOP
-NBOOTTRK.BIN
-W
-Q
A>
If you have SUBMIT and XSUB on your floppy, then you can use this submit file instead.
- Use the supplied PUTSYS utility to copy the boot track image to the
hard disk partition.
- Copy all the CP/M 3 *.SPR modules and CCP.COM to the partition.
- Run GENCPM in order to create a CPM3.SYS file, and specify the partition
drive letter as default system disk. You can erase the *.SPR files after
this.
- If you want to run PROFILE.SUB at startup, copy SUBMIT.COM and GET.COM
to the new partition.
- Copy any utilities you may want or need to the partition. Normally
that would include all the standard CP/M 3 utilities.
- Reboot!
Note: HCPMLDR cannot be executed from the CP/M 2.2
command prompt to bring up CP/M 3 (unlike the floppy version FCPMLDR.COM),
as the program expects hard disk partition parameters passed to it via the
Z80 index registers IX and IY from the boot loader chain. That's why it is
better to give the file a BIN extension to prevent accidental execution.
Last updated: 11-Apr-2018
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