ZX bus splitter

Board dedicated to 100×50×17 case (internal dimensions). Can be used with ZX Spectrum, Timex Computer 2068, Timex Sinclair 2068 and ZX81/TS1500. Unused contacts must be cuted out.

Can be used in several configurations:

• Two vertical boards with parallel tracks can be soldered - this gives three-ways bus splitter. Distance between vertical boards is 31.75mm (1.25").
• Universal board can can be connected as parallel -- simple, through interface can be made (extra memory, AY, joystick, printer, DMA controller, faster Z80, slots like: cartridge, ISA, YABUS). Distance between signal rows connectors -- 35.6mm (1.4").
• Can be cuted into 2 separate small boards -- this gives two double bus splitters or interface can be mounted vertically in a 100×17 case.

Version v004 contains in addition:

• Place for 74LS139 SMD chip, that can be used to swith output signals (like /IORQ and /MREQ) to one of 3 edge connectors or to none of them.
• Place for DIP-SWITCH to select active edge connector.
• Place for 74LS153 SMD chip that can be used to switch input signals (like /INT, /NMI) from one of 3 edge connectors or from none of them.
• Two places for microswitches, that can be connected to /RESET and /NMI. One is on the left, second on the right.
• Place for DB9 connector. (A Kempston Joystick port can be mounted using reconfigured places for SMD chips - 74LS138 and 74LS368 should be used in that case.)
• Places for LEDs.

Files for download

0012b.jpg 76.9kB (2007-08-13 14:53)

ZX.SPLIT for ZX81 - extra 74HCT139 decodes A5=1 and A7=1 for ZX1541 due to port conflict with joystick (port 29). Bottom view.

0012t.jpg 69.7kB (2007-08-13 14:51)

ZX.SPLIT for ZX81 - extra 74HCT139 decodes A5=1 and A7=1 for ZX1541 due to port conflict with joystick (port 29). Top view.

0006tc.jpg 80.4kB (2007-04-25 18:25)

ZX.SPLIT used as three-ways bus splitter. Top case view.

0006bu.jpg 107.7kB (2007-04-25 18:25)

ZX.SPLIT used as three-ways bus splitter. Bottom uncased view. Only one slot gets /MREQ can generate /ROMCS=1.

0006bc.jpg 93.3kB (2007-04-25 18:25)

ZX.SPLIT used as three-ways bus splitter. Bottom case view.

0006tu.jpg 113.7kB (2007-04-25 18:26)

ZX.SPLIT used as three-ways bus splitter. Top uncased view. The DIP-Switch selects active slot.

0002a.jpg 144.3kB (2007-04-28 00:51), uploaded by Jarek Adamski

ZX.SPLIT as bottom board for ZX81 interface. Please note how the board is corrected with 16 jumpers.

spli-005.zip 53.5kB (2006-10-31 18:39)

Board v005, Eagle data files. This project has bugs, but 32 boards are producted. Needs some changes when used as bottom of universal interface.

spli-004.zip 57.5kB (2006-10-31 18:39)

Board v004, Eagle data files. This project is correct.

howtocut.jpg 140.2kB (2006-10-31 18:30)

How the ZX.SPLIT can be cuted for ZX81, ZX Spectrum and Timex 2068. Also halves used as Timex Twister and ZX+3 fixer. (Board v005.)

split003.png 8.9kB (2005-04-12 21:24)

Recent project board view.

Links to other pages

http://8bit.yarek.pl/forum/viewtopic.php?p=100

[pl] Request for comments on forum.

See also

YABUS.ZXISA

ISA slots for ZX Spectrum (I/O mapped). LPT, 2×RS232, Floppy Disk Controller and sound card.

ZX1541 : ZX81

Commodore 1541 disk interface for ZX81.