Archive for July, 2011

Brain Board Assembly video

Saturday, July 30th, 2011

Check it out – done by one of the folks that picked a kit up up at K-fest.

Version 0.1 (pre-alpha) OS/X Scelbi emulator available

Saturday, July 30th, 2011

For the past several months, I have been working on a Scelbi/8008 emulator for Mac OS/X. Here is the first published screen shot of the running app. In this shot it is running Scelbal (Scelbi 8008 Basic).

Scelbi App version 0.1 Screen Shot

Scelbi App version 0.1 Screen Shot

At this time, there are currently 5 mostly working controls available with this app. All other controls either do nothing or react unpredictably.

  • The Memory->Clear menu function will clear 8008 memory to zeros
  • The Memory->Load menu function can be used to load 8008 memory with an intel hex formatted file. I have a copy of scelbal (Scelbi Basic) in this format available to download here. Other 8008 programs could be loaded, but the current assumption is that the PC is set to location 0x40 during reset.
  • The “INT” button will stop and reset the 8008, setting registers to zero, except for the program counter which is initialized to 0x0040. This is not the authentic use of the button, but it was handy for the initial bare bones implementation of this emulator
  • The “RUN” button will start the 8008, or if it is already running, do nothing.
  • The terminal section at the bottom of the window emulates a bit banged serial interface compatible with drivers commonly found with Scelbal. Input is expected to be in upper case. If this window does not respond to input, either the 8008 is stopped, or not currently monitoring the serial port or you have found a bug in the app. Note that unlike a real serial port, input to the port from the keyboard is queued to a length of 256 characters. Overflow conditions are not currently handled gracefully.

    You can download a copy of this app and try it for yourself, but keep in mind that the app is in early prototype stage. It is likely to behave unpredictably, hang and/or crash from time to time.

    The Scelbi/8008 emulation app can be downloaded from here.

    To run Scelbal (basic), do the following.

  • start the Scelbi app
  • clear 8008 memory (optional)
  • load 8008 memory with Scelbal.hex
  • click on the “RUN” button – you should see a “READY” message
  • type “SCR” – this clear’s Scelbal variables – if you don’t do this before entering your program weird things will start happening
  • you can now enter a basic program or basic commands directly
  • Be aware that there are several common 2 character error messages in Scelbal including “BG” for two big and “SY” for syntax error.

    The performance is throttled to approximately actual speed of a 500kHZ 8008. Try executing a “FOR” loop of 0 to 100 to get an idea of the incredibly slow performance of an 8008 running Scelbal. The first version of the 8008 emulator that I had running in a Unix shell environment was approximately 500 times faster than an actual 8008, and even that felt slow!

    The current implementation emulates the 8008 instruction by instruction. If I find the time and energy, I’ll convert it to a cycle accurate emulation and complete the hook up the Scelbi front panel depicted at the top of the app’s window.

    Have fun with it and be sure to let me know what you think.

    Wozanium Pack Source Code and Rom File Suitable for A2 Emulators Released

    Thursday, July 28th, 2011

    Ken Gagne was kind enough to take some Brain Boards out to K-fest and sold them at the vendor fair. Do to these extra K-Fest sales, I’ve now managed to cover my costs in producing the “Brain Board”. Thanks to everyone that has purchased one (or more) of these units.

    Because I’ve covered my cost, and it might be interesting to some folks, I’m now releasing the source code for the Wozanium pack.

    Also included, is a ROM file suitable for emulators, such as Virtual II. This allows you to run and debug Apple 1 software in the Apple II emulator environment. Just select the .ROM file as the ROM for your machine and reset your virtual machine. Just as in the Brain Board, right arrow will clear the screen. With Virtual II, you can download AIF files of A1 basic and assembly language programs and run them in your emulated Apple II, using the emulated cassette interface built into Virtual II. Note that this ROM version does not include the ACI driver at C100, so you must enter the Cassette driver by entering “D000R”, instead.

    You can build the source with the 6502 DASM cross assembler.
    Use the following command line:
    “dasm a2a1emulv5_1.asm -DBLD4ROMBD=0 -DHUSTNBASIC=0 -oa2a1rbh.o -la2a1rbh.lst”

    Included in this zip is

    * a1basic-universal.asm – Apple 1 BASIC modified to run on Brainboard/Wozanium (note copyright at beginning of this file)
    * COPYING.txt – GNU lincense for rest of Wozanium pack
    * a2a1emulv5_1.asm – Wozanium source code
    * a2a1emulv5_1.lst – Listing
    * a2a1emulv5_1.o – Object file
    * a2a1emulv5_1.rom – 12K rom file that can be used with A2 emulators, such as Virtual II.

    Click to download Version 5.1.

    More about the Brain Board can be found at:

    A 6800 based Apple-1 in the future?

    Monday, July 18th, 2011

    Looks like Eric of is working on a 6800 Monitor for the Apple 1. Several people have talked to me about doing this in the past, but it looks like Eric is really doing it as part of the annual retro-challenge. The obvious question is whether Eric or someone else will configure a physical clone of an Apple 1 for a 6800 and see if the hardware really works as designed.

    Only 2 Replica Datanetics PCBs left

    Saturday, July 9th, 2011

    It is highly unlikely that another run of these will be made. Checkout my Datanetics webpage and the Datanetics catagory of this blog for more information.

    Also, on a related note, it appears that has MM5740/AAE keyboard encoders in stock.