YABUS - universal 8-bit magistral

This magistral is dedicated to connect standardized I/O devices (ports) to micoroprocesor units (computers). Modules connected to the YABUS magistral are called YAMOD and their construction is independent from the computers they are connected to.

A ¹/₂C EURO slot is used. Female one on the board (YABUS) and male one in the module (YAMOD). Most of base modules uses only two outer rows of pins of the slot, what simplifies their construction.

A0..A15  - address output lines (16 bits) D0..D7  - data bidirectional lines (8 bits) /P0../P7  - decoded A5..A7 for A4=1 output lines /DMA  - DMA request input line /INT  - interrupt request input line /RD  - strobe output line for reading from port /WR  - strobe output line for writing to port /SEL  - address recognized input line* /RES  - reset output (optionally input) line GND, +5V, -12V, +12V - power supply lines

^* The module resets /SEL line (low) for addresses used by it. Low state disables other ports (e.g. pulls up the /IORQGE line in ZX Spectrum) opens the data lines buffer on buffered YABUS, also can disable module in slot of lower priority (YABUS can be wired with slots priority).

YAMOD.ATBUS - IDE (ATAPI) multiplexer

Purposes

• Access to harddisks and CDD.
• Access to ZIP drives and Compact Flash Cards.
• Generation of periodical interrupts (e.g for Timex FDD 3000).
• Real time clock.

Properties

• The board contains a muliplexer from 8-bit magistral of CPU to 16-bit magistral of IDE (ATA).
• Only PIO-0 mode is available.
• The disk is available in ports #B0..#B7, #BE, #BF.
• To read data from and write data to IDE device the DMA can be used (bytes are readed and written in correct order).
• The board can contain (as option) the real time clock (RTC) type DS 1287, DS 12887 or MC 146818 (battery backup includes also quartz generator). The RTC has 51 or 115 bytes of data.
• The RTC is available in ports #B8 (address) and #B9 (data).
• The RTC can generate periodical interrupt with programmable interval.

Mounting

• The board is inserted into free YABUS slot.
• The IDE drives are connected with 40 wires flat cable.
• Battery is connected with wires to battery slot (only for MC 146818).

YAMOD.ZXINPUT - input ports of ZX Spectrum

Purposes

• Using a PC keyboard with ZX Spectrum or Sam Coupé.
• using a PC Mouse with ZX Spectrum or Sam.
• Interrupts before each of 191 screen lines in ZX Spectrum.
• Using the mouse port as a RS232.

Properties

• The keyboard is fully programmable from computer level.
• Form the keyboard itself some keys can be programmed (macros).
• The PC Mouse is converted to:
  • Kempston Mouse for ZX Spectrum,
  • Sam Mouse for Sama Coupé
• The extra Sam keys are readable in #XXF9 and #FFFE ports.
• Reading from #F9 port provides interrupt information (line, frame, RS232).
• Writing to #F9 port sets the line, before which the line interrupt is generated. This applies only for values 0..191, for the values 192..255, line interrups are off.

Purposes

• Using YAMOD modules.

Properties

• Dedicated for most of ZX Spectrum models.
• Two unbuffered YABUS slot.
• Through edge slot.
• Disables ZX Spectrum internal ports with /IORQGE line.

Mounting

• Connected to the rear edge slot.
• Timex hardware need to be fixed to allow to disable internal Kempston Joystick.

Purposes

• Using of the PC harware (case, power supply, ISA cards, disk drives) under ZXVGS.
• Using CPM22QED with 59kB memory for programs (TPA).
• Using the UZI (U*ix Z80 Implementation).
• Using software for Z88 computer.

Properties

• Dedicated for ZX models with small board.
• Memory switching idea is close to memory map in Z88 (#D0..#D3 ports).
• Access to 512kB ROM and 16MB RAM, the internal memory is disabled and not used (except screen memory).
• One unbuffered YABUS slot.
• EPROM with extended boot code.
• Keyboard driven with YAMOD.ZXINPUT.

Mounting

• The AT286 requires advanced changes (removing the CPU, reconfiguration of interrupt controller etc.).
• The ZX board is connected to the AT286 board with an extra borad.
• The project is in initial phase now, please contact me if you are interested .

Purposes

• Using YAMOD.ATBUS as HDD driver inside the ZX Spectrum +3.
• Using YAMOD.ZXINPUT as keyboard and mouse driver.

Properties

• The YABUS allows to connect one YAMOD board inside.
• The FDD 3" can be replaced with 3.5" HDD.

Mounting

• The YABUS slot is located near printer edge slot.
• Signals are taken from Z80 socket.