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• UCSD Pascal for the Z80-MBC2!

  Just4Fun • 09/01/2019 at 15:45 • 3 comments

  Thanks to Michel Bernard (a member of the Z80-MBC2 User Group on FB) who did the porting, now UCSD Pascal is running on the Z80-MBC2!

  Michel Bernard originally used the trick to create a custom autoboot.bin file to be used with the "Autoboot" boot selection to load the OS.

  Because this porting is so cool, I've done a new IOS version and a new SD image to support UCSD Pascal in the same way as the others previous OS, adding a new "Disk Set" selection:

  
  To run UCSD Pascal you just need to update the new IOS and the new SD image (in the Files section) and select it from the usual "Select boot mode or system parameter" menu:
  
  
  

  
  In the new SD image there are two volumes (disks) SYS1: and SYS2:
  
  

  
  Here the execution of an example (SINE.CODE) already compiled on the SYS2: disk:
  
  

  
  In the folder "UCSD Pascal" inside the SD there are the original files and sources provided by Michel Bernard.
  A lot of documentation and books about UCSD Pascal can be found here.
  

• uCom is out!

  Just4Fun • 05/29/2019 at 09:20 • 0 comments

  I've done a separate "project page" for uCom (RS232 add-on card for the Z80-MBC2) here.

  The uCom board, as the uTerm VT100 board, has a "transparent" USB-serial adapter connector, so you can upload firmware to the Z80-MBC2 (using Arduino IDE) or load an Intel-Hex file (with iLoad) or use XMODEM to exchange files with a PC (running a terminal emulator that supports XMODEM file transfer) while the uCom is in use.

  Both the "mixed" power supply scenarios (USB-serial adapter not powered from USB but Z80-MBC2 powered and vice-versa) are managed by the HW, so you don't need to worry about it.

  uCorm can be mounted horizontally or vertically to the Z80-MBC2.

  The 3D printed custom angled brackets .STL files are the same of the uTerm.
  

  
  
  

  
  
  

  
  Here connected with a "vintage" RS232 terminal (Ampex 210 relabeled Kyber):
  

• uTerm is out!

  Just4Fun • 05/14/2019 at 07:40 • 0 comments

  I've done a separate "project page" for uTerm here.

  uTerm can be mounted horizontally or vertically to the Z80-MBC2.
  

  All the details including the 3D printed custom angled brackets .STL files are there.

  uTerm is a VT100 terminal with VGA out and  PS/2 keyboard with a power supply (for the Z80-MBC2 too). It has a "transparent" USB-TTL adapter connector, so you can upload firmware or load an Intel-Hex file (with iLoad) while the card is inserted. Both the "mixed" power supply scenarios (USB-TTL adapter not powered from USB but Z80-MBC2 powered and vice-versa) are managed. The video terminal is based on the ChibiTerm (https://hw-by-design.blogspot.com/2018/07/low-cost-vga-terminal-module-project.html).

  
  

  
  

  
  
  
  

  
  

  
  

• New IOS for XMODEM support

  Just4Fun • 03/10/2019 at 10:54 • 6 comments

  Because some people requested to use the XMODEM protocol to exchange files through the serial port, I've added the support for this protocol into CP/M 2.2 and CP/M 3 (banked only).

  XMODEM needs a full 8 bit binary data transfer, and this is not possible with the CON port (the CP/M port used for the console) with a "legacy" CP/M system installation because the CP/M Alteration Guide says to strip the eight parity bit when reading a byte from the console input.

  More, because the Z80-MBC2 uses a virtual serial port without handshaking there is also a timing problem when dealing with the 128 bytes packets used by the XMODEM protocol.

  So the support to the XMODEM protocol has requested changes in the IOS and  in the CP/M BIOS, and also in the Arduino core to extend the serial input buffer.

  Please note that with the new IOS the default speed of the serial port is now 115200 bps.

  To have the XMODEM support active, before the update of the new IOS firmware and the new SD image (see in the Files section),  you have to manually create a new "board variant" in the Arduino IDE and then change the default Rx input buffer size to 128 bytes in the "core" of this new variant.

  If you aren't interested into the XMODEM support, you can simply update the IOS and the new SD image as usual  without the need to create the new board variant. In this case the XMODEM will not work in the receive direction, but only in the send direction (from the Z80-MBC2 to a PC with a terminal emulator).

  
  
  HOW MANUALLY CREATE A NEW BOARD VARIANT (LINUX)

  In the following I'll assume an Arduino IDE 1.8.5 installation on a linux host and the MightyCore ver. 1.0.8. Anyway I've tried to make the procedure enough general to be used for other versions too.

  The first thing is find the directory where the MightyCore is located.

  If you have installed Arduino IDE 1.8.5 and then installed the MighyCore with the Board Manager with the usual .json "pointer", the MightyCore is located in the "~/.arduino15/packages/MightyCore" directory:

  Now you must locate the "~/.arduino15/packages/MightyCore/hardware/avr/1.0.8/cores" directory (note that the "1.0.8" part of the directory name depends on the MightyCore version, and so can be a different number if you have a different version of the MighyCore):

  ... Read more »

• Overclocking the Z80-MBC2...

  Just4Fun • 11/02/2018 at 09:51 • 4 comments

  Because the Mighty Core gives the chance to choice a 20MHz bootloader, I've decided to try to "overclock" the Atmega32A using a 20MHz quartz:

  You don't need others HW changes, just use a 20MHz quartz instead of a 16MHz one. The Z80 clock speed will be at 10MHz.
  

  You have to select the "20MHz external" option in the "Toos" menu of Arduino IDE before flashing the 20MHz bootloader:

  
  Of course you need to load the sketch again (using the "20MHz external" option). IOS will display the new clock speed:
  

  
  Remember that using a 20MHz quartz you are out of the Atmega32a specifications (the Atmega32a is rated at 16MHz max.), so you are in a "grey area" where things "may works"...
  

• CP/M 3 up and running on the Z80-MBC2!

  Just4Fun • 10/11/2018 at 06:58 • 0 comments

  With the latest IOS revision and the corresponding new SD image (see the Files section) there is one more option: the CP/M 3.0!

  With CP/M 3.0 it is possible use the 128KB banked RAM to have a wider user area (TPA) for programs and a more "evoluted" OS.

  
  

  TWO VERSIONS

  Just as example of how it is easy with CP/M 3.0 manage multiple configurations, I've done also a "non-banked" 64KB version. The switch from one version to the other can be done simply running a batch from the console itself.

  I've prepared two simple batch files to do that. From drive A: the command:
  

  submit sys64

  will set the 64KB "non-banked" version and then reboot the system.

  To activate again the 128KB "banked" version give the command (from drive A:):

  submit sys128

  
  

  NEW DISKDEFS FILE

  To use cpmtools or cpmtoolsGUI with the virtual disks of the CP/M 3.0 environment, you must update the DISKDEFS definition file (from the SD in the folder <SD>/cpmtools/) and use the "z80mbc2-cpm3" entry for all the 16 disks:

  Please note that for the CP/M 3.0 environment all the 16 virtual disks have the same structure and for this there is only one entry for all the CP/M 3.0 virtual disks.

  
  

  AUTOEXEC

  The AUTOEXEC switch for CP/M 3.0 works in a different way from the CP/M 2.2 and QP/M 2.71 implementations.

  Now there is a custom utility (AUTOEXEC) that checks the IOS flag and sets the exit code accordingly (using the BDOS function 108). This allow to use the CP/M 3.0 batch conditional execution (see the CP/M 3 Programmer Guide par. 1.6.3) to run any wanted command or program based on the status of the IOS AUTOEXEC flag.

  I've prepared an example using an other CP/M 3.0 feature, the "PROFILE.SUB" batch that is automatically executed at cold boot (if it exists). To activate it (in the drive A:) rename the file PROFILE.SU as PROFILE.SUB with the command:

  ren profile.sub=profile.su

  Now you can see how it works setting the AUTOEXEC flag on or off with the IOS "Select boot mode or system parameters" menu.
  

• QP/M 2.71 up and running (with IOS multi-boot management...)!

  Just4Fun • 09/17/2018 at 18:26 • 0 comments

  With the latest IOS revision and the corresponding new SD image (see the Files section) there is an interesting alternative to CP/M developed by MICROCode Consulting that supports also file timestamping, and it is 100% CP/M 2.2 "compatible".
  MICROCode Consulting has released the original installation files and all the documentation in their site with the "restricted usage" condition, that means free for non-commercial use and for personal use only.

  To enable timestamping (see upper screenshot) you need to install the optional RTC module.
  I suggest to read the QP/M documentation for the various commands (see the Downloads section in their site).

  
  

  AUTOEXEC

  The QP/M uses for the batch file the .QSB extension. So the AUTOEXEC file is now renamed AUTOEXEC.QSB. To enable the AUTOEXEC execution after the cold boot change the corresponding state to ON from the usual IOS boot selection menu. In the drive A: there is an example of AUTOEXEC.QSB file ready to run.

  
  

  IOS MULTI-BOOT MANAGEMENT

  Now the IOS has a new entry (8) in the boot menu to manage the OS multi-boot configuration:
  

  Each OS is associated with a set of virtual disks called "Disk Set", and changing the "Change Disk Set..." entry (8) will switch all the virtual disks of his "environment".
  

• CP/M 2.2 up and running on the Z80-MBC2!

  Just4Fun • 09/08/2018 at 18:24 • 0 comments

  The new IOS is out, and the CP/M 2.2 OS with it, and 16 disks are available (from A: to P:), each 8Mbyte large.
  

  With IOS (not for IOS Lite) the SD module is mandatory to run not only CP/M 2.2 but also for the stand-alone Basic and Forth interpreters. You need a microSD card (FAT16 and FAT32 are both supported) to store the content of the SD image file, retaining the directory structure.

  Pay attention on how the modules are inserted because their positions are fixed and absolutely not swappable (see the upper photo).

  To add, extract or delete files inside a virtual disk (virtual disks filenames on SD are "DS0Nxx.DSK", where "xx" is the disk number) it is possible use the cpmtools or cpmtoolsGUI utilities, with the diskdefs file in the \cpmtools directory of the SD zipped file.

  I suggest to use  cpmtoolsGUI (only for Windows) because is very easy.

  Unzip it into a folder and put the diskdefs file in the same folder.
  Select "z80mbc2-d0" only for disk 0, and "z80mbc2-d1" for the others (disk 1 - 15):

  NOTE: use cpmtoolsGUI only to add, extract or delete files inside a virtual disk. Not try to create new virtual disks files with cpmtools or cpmtoolsGUI because further processing is required for a valid virtual disk file.

• How use the ICSP port with the USBasp programmer under linux to burn the bootloader

  Just4Fun • 07/27/2018 at 15:57 • 0 comments

  A cheap and easy way to burn the Arduino bootloader is to use an USBasp programmer that is commonly available:
  

  The USBasp is also capable to give the power to the "target" using the VCC pin, but remember to check that the JP1 jumper is set to provide 5V to the target (as shown in the photo).

  Please note that the pinout of the USBasp is a little different from the "standard" ICSP (os ISP) pinout:

  
  In the previous picture it is possible see that pins 4 (TXD) and 6 (RXD) are not at GND as expected  by the standard ICSP port, and pin 3 is not NC.

  See the following picture showing the standard 10 pin ICSP pinout:
  

  
  So you must consider this when connecting the USBasp to the 6 pins ICSP port (J3) on the Z80-MBC2 (see the schematic):
  
  

  To avoid problems I suggest to use as GND pin 10 of the USBasp connector, and connect the other pins (VCC, MISO, MOSI,SCK, RST) accordingly.
  
  An handy way to connect the USBasp to the 6 pin ICSP port (J3) of the Z80-MBC2 could be to use a commonly available "10pin to 6pin" adapter like this:
  
  

  
  but I suggest not to use it "as is" because its internal connections are done for a "standard" ICSP port, and we have seen that the USBasp connector differs from the standard one.
  The schematic of the adapter shows that isn't compatible "as is" with the UABasp connector:
  

  
  To use it is a good idea isolate the pins 4, 5 and 6 cutting the trace on the PCB of the adapter that connects those pins together, and then check with a tester.
  In the following photo are shown the three cuts (thin red lines inside the green "circle") to do:
  

  
  

  BURNING THE BOOTLOADER FROM ARDUINO IDE:

  To easily burn the bootloader follow these "quick and dirty" steps (tested on a linux Mint OS with Arduino IDE 1.8.5):

  STEP 1: Connect the 10 pins connector of the USBasp programmer to the 6 pins ICSP port (J3) of the Z80-MBC2 (using wires or a modified adapter as discussed before);

  STEP 2: Verify carefully that any other connector of the Z80-MBC2 is not used, and verify that both the SD and RTC modules (if present) are removed from the board;.

  STEP 3: Only at this point connect the USB side of the USBasp programmer to an USB port of your workstation;

  STEP 4: Open a "terminal" window on your workstation and go to the directory where there are the Arduino IDE executables, and get the root privileges with the command:
  

  sudo su

  then run the Arduino IDE with the command:

  ./arduino

  STEP 5: Because Arduino IDE is running as the root user it is necessary re-install the "core" for the Atmega32. Open the Board Manager as you already did (anyway  the guide is here). Note that you must do this step only the first time you execute the Arduino IDE as root;
  

  STEP 6: Now from the Tools menu of Arduino IDE select "Atmega32" as "Board", "16 MHz external" as "Clock", and "USBasp" as "Programmer". Then you can burn the right bootloader (without playing with the FUSE setting) selecting "Burn Bootloader" from the same "Tools" menu.
  

  All done!
  

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