Editing Currah

'''Currah''' was a British [[computer]] [[peripheral]] manufacturer, famous mainly for the [[speech synthesis]] [[ROM cartridge]]s it designed for the [[ZX Spectrum]], [[Commodore 64]], and other 8-bit [[home computer]]s of the 1980s.

==Currah μSource for the ZX Spectrum==
The Currah μSource, commonly referred to as the ''Microsource'', from Quadhouse is a self-contained ROM cartridge with a full-function-two-pass macro [[Assembly language|assembler]], [[Forth (programming language)|Forth]] and a [[debugger]], all of which can interact with [[BASIC]].<ref>{{Cite web |title=Currah µSource |url=https://www.sinclaircollection.site/?page_id=3343 |archive-url=http://web.archive.org/web/20240228212618/https://www.sinclaircollection.site/?page_id=3343 |archive-date=2024-02-28 |access-date=2025-02-04 |website=Sinclair Collection Site |language=en-US}}</ref><ref>{{Cite news |date=June 1986 |title=Currah Microsource |url=https://worldofspectrum.org/hardware/feat2.html |work=Your Sinclair |issue=6}}</ref> It is also compatible with [[ZX Interface 1|Interface 1]].<ref>{{Cite news |title=Hardware World - The Forth Source |url=http://www.sincuser.f9.co.uk/048/usource.htm |url-status=dead |archive-url=https://web.archive.org/web/20120305202039/http://www.sincuser.f9.co.uk/048/usource.htm |archive-date=2012-03-05 |work=[[Sinclair User]] |issue=48}}</ref>

==Currah μSpeech for the ZX Spectrum==
The Currah μSpeech, commonly referred to as the ''Microspeech'',<ref>{{Cite web |title=Currah MicroSpeech |url=https://spectrumcomputing.co.uk/entry/1000081/Hardware/Currah_MicroSpeech |access-date=2025-02-04 |website=Spectrum Computing - ZX Spectrum games, software and hardware}}</ref> plugged into the [[expansion port]] on the back of the ZX Spectrum. Additional leads were provided to feed the sound and [[Ultra high frequency|UHF]] signal from the computer into the unit.  The TV aerial lead plugged into the unit and speech sounds were added into the UHF signal generated by computer.

By default, the unit "spoke" every key-press the user made, even the direction keys which came out as "CURSOR".  This could be controlled by a reserved variable <code>KEYS</code>. Typing
 LET KEYS=0
would turn this feature off.

===Programming speech===
Specific words and phrases could be spoken by assigning a value to the reserved string variable <code>S$</code>.  This was interpreted letter-by-letter unless brackets were used to denote other [[allophone]]s.  A simple example would be "(dth)is", (dth) representing the [[voiced dental fricative]] /ð/. Sixty-three allophones were provided.  Rudimentary pitch modulation could be achieved by altering the case of the letters—upper case letters being pronounced at a slightly higher pitch.

A more complex example:
  5 REM OKAY WISEGUY THIS IS IT
 10 <nowiki>LET a$=" (oo)K (AA)"</nowiki>
 20 <nowiki>LET b$="w(ii)z (ggg) (ii),"</nowiki>
 30 <nowiki>LET c$=" (dth)is iz it"</nowiki>
 40 <nowiki>LET S$=a$+b$+c$</nowiki>

{{Listen|filename=Okwiseguy.ogg|title=Currah Microspeech output|description=Audio recording of output from this program listing - 38 KB|format=[[Ogg]]}}

===Technical details===
The unit contained a [[Uncommitted Logic Array|ULA]] which worked on a WRITE command from the microprocessor, a [[Read-only memory|ROM]] containing the keyword speech patterns, and an [[General Instrument SP0256-AL2|SP0256-AL2]] speech processor. It also contained a clock for clear speech and an audio modulator to transfer the sound to the TV lead.  A small adjustment screw was provided, to allow fine tuning of the audio output.

The unit allocated itself the top 256 bytes of memory at switch-on and moved down the USR graphics and RAMTOP.  This made it incompatible with some programs, particularly games, which use that space for machine code.

For cost reasons, the unit did not provide for [[daisy chain (information technology)|daisy-chaining]] of further devices on the computer's expansion port.  Many [[joystick]] [[computer bus|interface]] manufacturers took the same approach, meaning that you could not have a joystick and the MicroSpeech unit plugged in at the same time.

''Booty'' ([[Firebird Software Ltd.|Firebird Software Ltd]]) detected the presence of a MicroSpeech unit and presented the user with a completely different game to that which would be played if the MicroSpeech unit was not present.<ref>{{cite web |title=Booty Hidden Game Review |url=http://zxplanet.emuunlim.com/booty_hidden_game.htm |access-date=2012-11-02 |website=ZX Planet - RELIVE YOUR CHILDHOOD |publisher=}}</ref>

==History==
Currah was acquired by [[DK'Tronics]] in 1985.<ref>{{Cite news |last=Cox |first=Kevin |date=April 1985 |title=Minding his own business |url=http://www.users.globalnet.co.uk/~jg27paw4/yr13/yr13_72.htm |work=[[Your Spectrum]] |issue=13}}</ref> DK'Tronics continued to manufacture the MicroSpeech unit, and many of their software titles (such as ''[[Maziacs]]'' and ''[[Zig Zag (1984 video game)|Zig Zag]]'') supported it.

==External links==
*[http://www.crashonline.org.uk/02/currah.htm Review of the product] at ''[[CRASH (magazine)|CRASH]]'' magazine
*[https://www.worldofspectrum.org/infoseekpub.cgi?regexp=^Currah+Computer+Components+Ltd$&loadpics=1 List of Currah products at World of Spectrum] '' community website

==References==
{{reflist}}
{{Speech synthesis}}{{Sinclair computers and clones}}
[[Category:Defunct computer companies of the United Kingdom]]
[[Category:Defunct computer hardware companies]]
[[Category:Home computer hardware companies]]
[[Category:Speech synthesis]]
[[Category:ZX Spectrum]]