MHT Speech Synthesizer

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MHT Speech Synthesizer aka Sintetizador de voz (MHT Ingenieros)


It uses a SP0256(-AL2?) chip.

  • The I/O address is &FBE0. (only A10,A7,A6,A5 and A4 are decoded)
  • The clock frequency is unknown (as shown on the photo, it uses an oscillator, ie. NOT the 4MHz signal on the expansion port).

Port FBE0h READ:

 bit 6   Status 1 (0=Speech Busy, 1=Ready/Halted)   (SBY Pin, Speech Busy)
 bit 7,D5-D0 Not used (garbage, probably usually highz)


 bit7-6 Ignored
 bit5-0 Allophone number               ;data can be send when Status.Bit?=0

Now, thanks to Jose Leandro, the hardware specialist of the spectrum, with his famous page :

We can know more about this hardware.


The part numbers on the chips seem to be scratched-off (or covered by paint, or is it just old glue from stickers?).

The "GI" logo on the large chip implies that it is the popular General Instrument SP0256 speech chip, probably the standard -AL2 version (the ending L2 may be still visible? not sure there - on the photo it vanishes under the pot axis).

The clock frequency of the oscillator isn't visible (from the perspective from where the photos were taken).

The GNDed pins somewhat confirm that it is a SP0256 (Pin1=Supply GND, Pin10,11=A8,A9, ie. only 6bit allophone numbers used).

Caution - There are two files, Image:MHT-sintetizdor_de_voz-005.jpg and Image:MHT-sintetizdor_de_voz-008.jpg circulated in internet.

Despite of their filesnames, they do NOT show a MHT speech synthesizer - please do not add these files to this page!

The hardware shown on those pics is an ARA Video Digitizer, nothing to do with MHT Speech.

Software Covertape


Other CPC Speech Synthesizers