[Coco] s/sc on os-9 l2
Luis Antoniosi (CoCoDemus)
retrocanada76 at gmail.com
Fri May 10 10:32:38 EDT 2013
thxs!
On Fri, May 10, 2013 at 10:23 AM, tim lindner <tlindner at macmess.org> wrote:
> On Fri, May 10, 2013 at 6:38 AM, Luis Antoniosi (CoCoDemus)
> <retrocanada76 at gmail.com> wrote:
> > Do you have a schematic or image of this fix ?
>
> I dont know if any schematic has existed for this fix, but I did find it:
>
> ftp://os9archive.rtsi.com/OS9/OS9_6X09/SYSMODS/SS_Pak_Driver.lzh
>
> It is inside that archive called sspak.txt.
>
> I've attached the file here (the ascii art will need a fixed-width font):
>
> Speech-Sound Pak 1.78 MHz. Modifications
> This text attempts to explain how to modify the Radio Shack/Tandy
> Speech-Sound Pak (catalog numbers 26-3144 and 26-3144A) to work with the
> COCO3
> at 1.78 MHz.
> Please note that the level 1 version 02.00.00 COCO OS-9 SSCPAK driver
> doesn't work properly with a modified Speech-Sound Pak. Included with
> this
> file should be a new driver (SSPak) and a new descriptor (SSP) which work
> on
> either level 1 or level 2 COCO OS9. We hope that they are an improvement
> over
> the original drivers! SSPak and SSP are Public Domain, and source is
> included, so feel free to distribute them, or to customize them if you
> wish.
> The hardware modifications are fairly straightforward, but vary
> slightly
> between the two models (26-3144 & 26-3144A). Make sure that your
> Speech-Sound
> Pak is one of the Paks described, and that you make the correct
> modifications.
> Externally, the 26-3144's that we have seen have a Radio Shack label,
> while the 26-3144A's have a Tandy label. Internally, the 26-3144 uses a
> 2907
> transistor and the inductor (marked L1) is in a resistor-style (axial)
> package. The 26-3144A uses a different transistor, and the inductor (also
> marked L1) is in a small plastic box. In both Paks the transistor &
> inductor
> (coil) are close to the post hole in the circuit board.
> It is necessary to change the transistor in order for the Speech-Sound
> Pak to work properly in most cases. We have seen only one unmodified Pak
> which worked when the COCO3 was running at 1.78 MHz. The voltage inverter
> circuit used must supply at least -5VDC in order for the output OP-AMPs to
> function. Unfortunately, the transistor used is sensitive to the frequency
> input to the circuit. The input signal used is derived from the bus E
> clock.
> When the COCO3 runs at 1.78 MHz, the circuit typically produces only
> -2.5VDC,
> which is not sufficient for the OP-AMPs.
> The 2N3906 is a PNP transistor. Looking at the flat face, with the
> pins
> pointing down, the pin out should be Emitter, Base, Collector from left to
> right. The 2N2907 transistor should have the same pin out as the 2N3906.
> The
> transistor in the 26-3144A Pak should have a pin out of Emitter, Collector,
> Base when viewed in the same manner as the 2N3906. When installing the
> 2N3906
> transistor into a 26-3144A circuit board you must swap the Base and
> Collector
> pins so that they match the original transistor's pin out.
> 26-3144 Voltage Inverter Transistor Change:
> 1) Make note of the 2N2907's pin out & orientation. Most
> manufacturers
> should use the same pin out, but its worth checking.
> 2) De-solder the 2N2907 transistor & remove it from the Speech-Sound
> Pak circuit board.
> 3) Solder a new 2N3906 transistor into the Pak's circuit board. The
> 2N3906 should be oriented the same as the 2N2907 that was removed,
> but again its worth checking the pin out!
> 26-3144A Voltage Inverter Transistor Change:
> 1) Make note of the transistor's pin out & orientation. Most
> manufacturers should use the same pin out, but its worth checking.
> 2) De-solder the transistor & remove it from the Speech-Sound Pak
> circuit
> board.
> 3) Carefully bend a new 2N3906 transistor's base and collector pins
> so as
> to swap the holes they fit into. Make sure that they do not touch
> each other or anything else that could cause a short circuit.
> 4) Solder the new 2N3906 transistor into the Pak's circuit board. The
> 2N3906 should be oriented the same as the transistor that was
> removed
> (except 2 pins swapped), but again its worth checking the pin out!
> The other hardware change required alters the clock frequency of the
> Pak's micro-controller and sound effects chips. The Speech-Sound Pak uses
> a
> frequency doubling circuit to provide the clock signal for these ICs.
> These
> chips use a typical clock of 2 MHz, and the old COCO's clock of .89 MHz was
> doubled to provide the Pak's ICs with a 1.78 MHz clock. This is close
> enough
> to 2 MHz that the Pak runs properly. However, when the COCO3 runs at 1.78
> MHz, this frequency is doubled to 3.56 MHz, which is well above the ideal 2
> MHz clock. We've found that most Paks will work at this speed as long as
> the
> voltage inverter has been modified. If the clock doubler isn't modified,
> the
> speech synthesizer will sound normal, but the sound effects will be one
> octave
> higher than they should be. That is, sound effects will not sound as they
> should, with the result that software which uses the Pak for sound effects
> will probably disappoint you.
> Here's a diagram of the 74LS86 (viewed from above), where the 'D'
> represents the notch at the "pin one" end of the chip. Some chips do not
> have
> a notch to indicate pin 1. In that case, look for a small indentation
> (represented here by the lower case 'o') close to pin 1 to find the
> orientation of the chip's pin numbers. The upper case 'O's represent pins.
> pin 14 pin 9
> ! !
> +O---O---O---O---O---O---O+
> ! !
> D 74LS86 !
> !o !
> +O---O---O---O---O---O---O+
> ! !
> pin 1 pin 7
> Here are two alternatives to fixing the Speech-Sound Pak's clock rate.
> The first will limit your Pak to use at 1.78 MHz, unless you restore the
> Pak
> to its original state before using it at .89 MHz. The second will allow
> you
> to switch the Pak to operate at either .89 MHz or 1.78 MHz. Both fixes
> will
> work on either the 26-3144 or 26-3144A Speech-Sound Pak.
> 1.78 Mhz COCO3 Clock Frequency:
> 1) Cut the trace leading from the Pak's bus Q signal (card-edge pin
> 7) to
> pin 9 on the 74LS86.
> 2) Connect pin 9 of the 74LS86 to the Pak's ground.
> .89/1.78 MHz COCO Switchable Clock Frequency:
> 1) Cut the trace leading from the Pak's bus Q signal (card-edge pin
> 7) to
> pin 9 on the 74LS86.
> 2) Connect pin 9 of the 74LS86 to the centre (common) pole of a small
> SPDT (Single Pole Double Throw) switch.
> 3) Connect one outside pole of the SPDT switch to the Pak's ground.
> 4) Connect the remaining pole of the SPDT switch to the Pak's bus Q
> signal.
> 5) Mount the SPDT switch on or in the Pak, wherever its convenient,
> and
> will not accidentally short to anything.
> We hope that your Speech-Sound Pak modification goes as smoothly and
> successfully as ours did (once we figured out the voltage inverter problem
> it
> was all downhill!). Thanks to Kevin Darling and others who believed that
> there was no good reason why it wouldn't work!
> Speech-Sound Pak modification by Bill Boogaart (CIS 72075,615), Mario
> Dilallo, and Bruce Isted (CIS 76625,2273).
> Radio Shack TM Tandy Corporation, OS-9 TM Microware & Motorola, Inc.
>
> --
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> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco
>
--
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