ZX Spectrum and ZX81 keyboard matrix diagrams

For experts to discuss very technical stuff and newbies to ask why the Spectrum they bought off ebay doesn't work.
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1024MAK
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ZX Spectrum and ZX81 keyboard matrix diagrams

Post by 1024MAK »

Image

Image

Mark
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Ast A. Moore
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Re: ZX Spectrum and ZX81 keyboard matrix diagrams

Post by Ast A. Moore »

Identical?
Every man should plant a tree, build a house, and write a ZX Spectrum game.

Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
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1024MAK
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Re: ZX Spectrum and ZX81 keyboard matrix diagrams

Post by 1024MAK »

Ast A. Moore wrote: Sun Mar 15, 2020 4:26 pm Identical?
Look again...!
:!: Standby alert :!:
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :dance
Looking forward to summer later in the year.
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Ast A. Moore
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Re: ZX Spectrum and ZX81 keyboard matrix diagrams

Post by Ast A. Moore »

1024MAK wrote: Sun Mar 15, 2020 4:40 pm
Ast A. Moore wrote: Sun Mar 15, 2020 4:26 pm Identical?
Look again...!
Mmm . . . Uh . . . Okay, lemme jot it down, then.

KBD0—outermost key of a semi-row
KBD4—innermost key of a semi-row

That’s a check for both matrices.

Address lines:

A11—keys 1 through 5 on both
A12—keys 6 through 0 on both
A10—keys Q through T on both
A13—keys Y through P on both
A9—keys A through G on both
A14—keys H through Enter (New Line) on both
A8—keys Caps Shift (Shift) through V on both
A15—keys B through Space on both

:? I don’t know, man. They look identical to me.

Oh, oh, do you mean the pins of the physical connectors are arranged differently? Is that it? D’oh! :lol:
Every man should plant a tree, build a house, and write a ZX Spectrum game.

Author of A Yankee in Iraq, a 50 fps shoot-’em-up—the first game to utilize the floating bus on the +2A/+3,
and zasm Z80 Assembler syntax highlighter.
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1024MAK
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Re: ZX Spectrum and ZX81 keyboard matrix diagrams

Post by 1024MAK »

Yes, you can’t just plug a ZX81 keyboard membrane into a ZX Spectrum or plug a ZX Spectrum membrane into a ZX81.

Mark
:!: Standby alert :!:
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :dance
Looking forward to summer later in the year.
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