[img] Sinclair ZX Spectrum Circuit Diagrams
MDFS::Info.Comp.Spectrum.Circuits Search

I am gradually scanning and cleaning up the piles of circuits diagrams I have. These are various bits of Spectrum hardware that I have built and used, and other hardware that I have examined and worked out the circuit diagrams from.
Title   Paper Size Description
Backplane
Ctrl2.gif

diagram
 
654x973 A4P
 
23K
Backplane system for the Spectrum. I prototyped a lot of my hardware with this.
Keyboard       Spectrum keyboard systems.
Key+Joy.gif
Key+Joy.jpg
ASCkbd.jpg
diagram
picture
picture
916x1000 A5P
30K
52K
ASCII keyboard on port &FD/&F9 and Kempston joystick on port &1F.
AtomKbd.gif
AtomKbd1.jpg
AtomKbd
diagram
picture
documents
2048x2452 A4L 104K
26K
9K
External matrix keyboard on port &FE with shifted keys and addition symbol keys.
ExtKbd.gif
ExtKnd
diagram 2048x2452 A4L 99K
5K
Experimental extended keyboard interface.
2-chip Joystick diagram 2912x2064 A5L 43K 2-chip Kempston joystick interface. Uses just a single 74LS365 hex buffer, a single 74LS32 quad-OR, a Spectrum edge connector and a 9D plug. This type of joystick interface fully decodes IN 31, so does not interfere with interupts in IM2. The addition of a 35p multiple OR gate decodes ~IORQ, ~RD, A7, A6 and A5 to correctly respond to IN 31.
1-chip Joystick diagram 2912x2056 A5L 45K 1-chip Kempston joystick interface. Uses just a single 74LS365 hex buffer, a Spectrum edge connector and a 9D plug. This is the type of joystick interface that causes interupt problems in IM2 as it only decodes ~IORQ and A5, so any I/O access with A5=0 reads the joystick. So, an interupt acknowledge with ~IORQ=0, but ~RD=1 and ~WR=1 accesses the joystick.
ROM1.gif
ROMBox1.jpg
ROMBox2.jpg
diagram
diagram
picture
picture
2912x4096 A4P
264x512 A5P
127K
79K
63K
Single socket external ROM box. Can plug in an 16K or 32K ROM. ROMs selected with OUT &FD,&nn.
b4=0 - external ROM, b4=1 - internal ROM.
b6=0 - lower 16K, b6=1 - upper 16K.
Gives:
  • &00 - external ROM lower 16K
  • &10 - internal ROM
  • &40 - external ROM upper 16K
ROM4.gif diagram 2912x4096 A5P 165K Four-socket external ROM box. Can plug in a combination of 16K and 32K ROMs. ROMs selected with OUT &FD,&nn.
b4=0 - external ROM, b4=1 - internal ROM.
b6-b7=external ROM number
Gives:
  • &00 - 16K ROM 0 or lower 16K of 32K ROM 0
  • &10 - internal ROM
  • &40 - 16K ROM 1 or upper 16K of 32K ROM 0
  • &50 - internal ROM
  • &80 - 16K ROM 2 or lower 16K of 32K ROM 2
  • &90 - internal ROM
  • &C0 - 16K ROM 3 or upper 16K of 32K ROM 2
  • &D0 - internal ROM
IF1.gif
IF1sm.gif
IF1th.gif
IF1.jpg
diagram
diagram
diagram
picture
4096x2896 A4L
2048x1448 A5L
720x509 A5L
176K
68K
13K
7K
Sinclair Interface 1. Initially drawn by hand in 1987, being redrafted.
Hardware       Spectrum hardware documentation.

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