ZXATASP Interface

ZXATASP v1.6, memory unit at top

ZXATASP v2, memory unit and a CompactFlash socket onboard.

ZXATASP is a IDE 16-bit harddrive interface(much like a sinclair microdrive). It plugs to edge
connector on any spectrum.

  • 1x Edge connector
  • 1x CompactFlash socket
  • 1x IDE socket (harddrive, needs extra psu)
  • 128k or 512k mem (onboard option)
  • 1x ZXBUS type1

  • Requirements:
  • ZX Spectrum (runs on 16,48,48+,128,+2,+2A,+3)

  • ZXATASP's 512k is very flexible, use it as a 'Softrom', run InterfaceII roms, you can have several different OS roms, ResiDOS to access IDE drives.
    It has 32 pages of 16k, it's paged in instead of Spectrum rom and can by a simple command page back Spectrum rom.(No need to exchange Spectrum rom)
    By inserting 'upload' jumper you can read Spectrum rom and write to a ram page and by some out commands change page, this allow upload to ram by basic.

    ZXATASP document

    Serial Interface

    The picure is the serial interface for ZXBUS type1.(ZXATASP)

    Highspeed serialport 9-pin dsub, connect this interface by zxbustype1 connector or spectrum edge connector look bellow for different versions.
    Filetransfer between eg. a Spectrum and a pc.

    JessaI/O (ZXBUS type1)Schematic rev 0.9

    JessaI/Oe(edge) Interface with kempston joystick, schematic v1.1
    Optional 34-pin(ZXBUS type1) socket for future expansions, eg, ZXAY module (untested)

  • Highspeed 16550 chip
  • Standard pc-type DSUB9
  • Max speed - 460800 baud

  • Div-table:
  • 6144 - 75
  • 3072 - 150
  • 1536 - 300
  • 768 - 600
  • 384 - 1200
  • 192 - 2400
  • 96 - 4800
  • 48 - 9600
  • 32 - 14400
  • 16 - 28800
  • 8 - 57600
  • 4 - 115200
  • 2 - 230400 (not tested)
  • 1 - 460800 (not tested)

  • ZXAY

    ZXAY interface ! (AY-3-8912) this soundchip is already on 128K Spectrums.
    This interface is for 16/48k Spectrum that has no AY.
    I/O is the same as on 128k Spectrums. Stereo output,
    A+C & B+C channel, connects by zxbustype1.

    ZXAY (ZXBUS type1) schematic v0.1 (untested)


    ZXMEM interface !
    This interface is for 16/48k Spectrum as now. (I haven't checked if it's possible on others)
    Last 32k cpu space is expanded upto 32MB memory paged, connects by zxbustype1.

    Page unit I/O 95d. 256K area available on both 32-49 & 49-64K cpu area.
    Bits 0..3, 32-49k cpu mem area, 256K/16K = 16 pages
    Bits 4..7, 49-64k cpu mem area, 256K/16K = 16 pages
    Same mempage can exist on both areas. (useless at this point)
    Page unit I/O 351d.
    Bits 0..6, 32MB area, 32768K/256K = 128 pages
    Bit 7 disable the mempage unit until reset.

    The last 32K memory has to be removed or disabled on 48K Spectrum.
    The 16K Spectrum needs no changes.

    ZXMEM 512K/1MB version, (ZXBUS type1) schematic (untested)

    This schematic is final, minimum 512K to max 32MB is possible.

    I2C bus

    RealTimeClock for date & time, I2C 4-wire plug for future expansion (128 units).
    The plug has +5V, GND, serialclock, serialdata.
    For spectrum network only a wire with serialclock & serialdata is needed to be connected.
    Ofcourse we need the software, as now there is no software for the interface.

    This features a philips I2C bus with a I2C-RTC chip.
    I2C controller 8584 is a multimasterbus this allows spectrum network and other pheriperals to be connected in future.
    Adapter from I2C >> PC will be possible 2.

    Both interfaces has no SMD parts, easy to solder.

    I2C Schematic rev 1.0 zxbustype1 VERSION(untested)

    ZXCF Interface

    Old dreams came true....,
    A mass storage unit that can be build into spectrum, no extra psu, no clumsy units, no extra noice, affordable media, and a bonus I couldn't imagine, the versatile memory unit. The memory unit would probaly still be nothing if it wasn't for Garry Lancaster's ResiDOS, this really expands spectrum.
    I hope you will find ZXCF as exciting as for me.
    Sami (2003)

    ZXCF is a CompactFlash storage interface(like a sinclair microdrive/+D)

    Features: ZXCF
  • 1x Compactflash slot 4MB-1GB (no hi-speed)
  • 512k or 1024k onboard memory
  • ZX Spectrum (runs on 16,48,48+,128,+2,+2A,+3,+3e)

  • It can only be done with issue2, other issues the pcb won't fit.
    (The ULA on later issues is lower down)
    Just above the ZXCF you can se that I had to extend the left membrane connector.
    It took some planning to do this, I don't recomend anybody todo this !! ;-)

    ZXCF Schematic rev 1.41 zxbustype1 VERSION
    ZXCF document

    ZXEXP/CPU adapter

    ZXEXP/2 ZX Spectrum edge expansion

    ZXEXP adapter plugs to rear edge connector on spectrum, you get reset, nmi, zxbustype1(my own creation) with this 34-way connector several interfaces can be connected together. eg. ZXEXP > ZXCF & ZXAY several at same time.
    And it's flexible with a 34-way ribbon cable.

    This bus is on following interfaces & addon.
    ZXCF, ZXATASP(1.6 >), JessaI/O, ZXAY.
    ZXATASP memexp v1.50 has a extra connector so this only works on ZXATASP 1.6 > 1.7

    ZXEXP Spectrum edge expansion

    ZXEXP2 topside (Reset & NMI connectors on each side)
    I haven't cut out the 'key' on edge thru yet ;-)

    ZXEXP2 underside (I have used surface mounted resistor & capacitor)

    ZXEXP sch&pcb (eaglecad v4.09)
    This has one zxbustype1 connector, NMI & RESET.
    Plugs to spectrum edge and gives you a zxbustype1 connector for eg. ZXCF.

    ZXEXP2 sch&pcb (eaglecad v4.09) *20030807*
    This has one zxbustype1 connector and a spectrum edge thru, NMI & RESET
    Plugs to spectrum edge and gives you a zxbustype1 connector for eg. ZXCF & a thru edge expansion for other interfaces.

    The black areas are cut out.

    CPU adapter v1.2 sch&pcb (eaglecad v4.09)
    This has one zxbustype1 connector and NMI, RESET
    Plugs to spectrum cpu socket and gives you a zxbustype1 connector for eg. ZXCF.
    A special 40-pin dil socket is needed for this, legs on it has to be longer.
    +2,+3 Spectrums the cpu is in a socket, easy mounting.
    128K spectrum it's soldered, need to remove it first.
    16/48K spectrum, I have put alot work on the size to make it fit, it might be to thick so you can't close the box, if using a low-profile socket and solder it to main board it might go.

    There are still the ROMCS lines that have to be soldered to main pcb, look further down for more info.

    Solder your own ZXBUStype1 to Z80 CPU connection (CPU adapter)

    Please note that the cpu is not mounted in same direction on all spectrums.

    If you look at how ZX Spectrum48k & +3 is connected to ZXCF then follow this two diagrams and connect signals found on zxbustype1 to z80cpu.
    AB 0-15 on zxbustype1 is on Z80 A 0-15. VCC is same as +5V.
    On zxbustype1 pin 27,29,31 has to be soldered to spectrum eg. edge, you won't find these ones on z80cpu.
    If you are to solder it to a 16/48/128/+2 you only need pin 27.(29 & 31 unconnected) If you are to solder it to a +2A/+3 you will need pin 29 & 31. (27 unconnected) This only applies if you are to solder the zxbustype1 into a spectrum.

    pin 29 & 31 soldered to +3 main board. It doesn't matter the order of them.

    Fixes for speccy

    ZX Spectrum +2A/+3 Videofix

    Old design, what I have suspected but never got around until now is that audio is mixed together with videosignal, this causes distorsion on picture during audio output and it causes many monitors not to detect the color signal. To fix this you need to remove or lift up one leg of the cap(C24) that provides the modulated audio signal, this is marked with red on picture.

    Tape loading problem?

    Main purpose of it is to load tapes from a PC soundcard to Spectrum, mostly there is not enough output on a PC soundcard.

    I have made this as simple as possible and I did think of a build in Spectrum fix but if you have like me several Spectrums then this external audiobooster is the best solution.
    The AMP unit cost about 9.
    Amp is a KEMO article no. M032, should be easy to get.

    Connectors in this example is for the ZX Spectrum 16/48/48+/128 version.
    You can still use it for the +2/+3 Spectrums but you have to get a PSU for the AMP.

    plus4 screen memory Schematic concept