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  1. gertk

    Simple, generic 80x24(25) display card

    Not much: a couple of 6845 registers need to be set up, just like a MDA card (in fact exactly like an MDA card) and you can trigger some extra functions through specific IO ports to enable the graphic functions and RAM pages. After setup the card shows up as 4 k of video ram space with a 80x25...
  2. gertk

    Simple, generic 80x24(25) display card

    I recently hooked up a Tamarack 8 bit ISA Hercules Graphic Card to my Microprofessor 1 Plus just for fun. Used a GAL 16V8 to generate the necessary ISA bus signals and a LS123 to delay and drive the /WAIT line of the Z80. Works quite nice but ofcourse it does not generate VGA, I use a Qtek MDA...
  3. gertk


    Well, there was ofcourse CP/M86 ... ;)
  4. gertk

    Local variables in BBC Micro

    Tried it on Z80 BBC basic on my 'Kaypro mini'
  5. gertk

    Local variables in BBC Micro

    Since you can use recursion on the BBC it is designed so local variables are 'fresh' for every call to the function. Just try it out: REPEAT INPUT "Enter an INTEGER less than 35 "num UNTIL INT(num)=num AND num<35 fact=FN_fact_num(num) PRINT num,fact END : DEF FN_fact_num(n) IF n=1 OR n=0...
  6. gertk

    Commodore 64 weird situation

    Another common fault where multiple chips are fried: a bad power supply. Always check voltages from the supply before connecting it.
  7. gertk

    BASIC interpreter for SunOS 4.1.4/Solaris 1.1.2

    Might take a look at x11basic: https://x11-basic.sourceforge.net/
  8. gertk

    Kaypro 4 Plus 88

    Have a look at: http://q7.neurotica.com/Oldtech/Kaypro/Kaypro488.html There are some photo's of the innards of the Kaypro 4 plus 88 including the 8088 board (alas a bit obscured by the cables) but might give some insight how it wa attached to the Z80 board.
  9. gertk

    Olivetti ETV 300 : Can I use the typewriter part as a serial terminal to mimic a teletype?

    A little Google-ing and translating from this website: The system also included a typewriter (it appears to be from the ET series) equipped with a serial interface LCU ( Line Control Unit ) so as to use the keyboard section as input and the printer section as output. The connection between...
  10. gertk

    Kaypro 1 quadrople image.

    Mangled a pin of the 6845/6545 perhaps?
  11. gertk

    Educate me on multitasking under MPM - what do I need for "power user" usage?

    Thinking of it, the Amstrad PCW (or Schneider Joyce) may be an excellent candidate for MPM as it has 256 to 512 kByte of memory available in 16 kByte chunks which also can be mapped in 16 kByte offsets: &F0 O Select bank for &0000 &F1 O Select bank for &4000 &F2 O Select bank for...
  12. gertk

    24 pin dot matrix impact printers popularity back in the day.

    I had a NEC P6 24 pin printer connected to my Atari ST and with the Signum3 DTP-ish software package I printed a lot of invitations, letters, school work, wedding cards and such. It printed absolutely beautiful (for those days) and quality was almost on par with a 300 dpi laser printer.
  13. gertk

    MCLZ8 fun with NABU

    Note the Teensy has 3.3V IO so you need the MAX3232 instead of the MAX232, otherwise you need to level convert the input to the Teensy first. Can be done with some resistors but maybe you run into speed problems then.
  14. gertk

    Category for Agon Light?

    As far as I can tell the only 'forum' Agon Light is using is FB and since I am not using FB... I am fiddling here with a sort of 'Agon Ultralight': VGA32 (with ESP32) miniboard which handles all the work: emulating a Z80 (I could do 6502) and generating VGA signal, sound, SD card storage etc...
  15. gertk

    Your first Atari, and last?

    My first Atari was a 400 (a leftover in the shop I worked), got a 1050 diskdrive with it and expanded the memory myseff. Can't remember where it went. Later on I got a 260ST, updated it to 1 Meg and a SH204 harddisk, the drive in that got replaced by a 'real' SCSI 2 GB drive, after that a Mega...
  16. gertk

    Need instructions on transfer of non disk image files via serial into Kaypro II

    You can send an Intel hex file over serial as text, save it on the CPM side (you can use PIP for that too!) and use DDT to read it into memory. After that you can use 'SAVE' to save it as a binary to disk. Crude but effective.
  17. gertk

    1981 Toshiba T250 Monochrome CRT board issues

    It seems like a contradiction if the base drive of Q105 is ok and there is no collector current (note: through T101 the base is mostly current driven since 'high voltage' transistors of that era have very low hfe or gain values). If the collector is at 'solid +12V' it could mean: a) the...
  18. gertk

    Commodore 128 Issue with Control Port 2 is Utalized

    The keyboard matrix with the C64/128 is shared with the joystick ports. So my guess is that the RetroRadionics Arcader is loading some pins of the joystick port and thereby interfering with the keyboard. Try for example holding a standard joystick in port 2 to one direction and then typing...
  19. gertk

    They may have found (most of) the Apple 1 Prototype Board

    I assume you are kidding here or do you have any evidence for that ?