Soundboard behind ZXPAND problem SOLVED

[Andy Rea]

Well i am truly confused, my soundboard is a home made affair using a AY-3-8912 took from a non-working spectrum with a single-16v8 gal for clock division and io decoding, the data bus is connected at the edge-connector (there are plated holes ideal for wires next to the edge-connector) the address lines A0, A1, A2, A3, A5, A6, A7 are connected next to the CPU there is an un-used place for a resistor pack, again ideal for small wires, the other control signals , are taken from various plated throught holes on route from the CPU to the edge connector.

Electrically i can't think of anything that could be different if i connected it all to the back of my ZXpand. is it possible to link to the schematic of the sound card you are using ?

Andy.

p.s. i have looked on the German forum but I am not sure which schematic you are using.

[Paul]

Well i am truly confused, my soundboard is a home made affair using a AY-3-8912 took from a non-working spectrum with a single-16v8 gal for clock division and io decoding, the data bus is connected at the edge-connector (there are plated holes ideal for wires next to the edge-connector) the address lines A0, A1, A2, A3, A5, A6, A7 are connected next to the CPU there is an un-used place for a resistor pack, again ideal for small wires, the other control signals , are taken from various plated throught holes on route from the CPU to the edge connector.

Electrically i can't think of anything that could be different if i connected it all to the back of my ZXpand. is it possible to link to the schematic of the sound card you are using ?

Andy.

p.s. i have looked on the German forum but I am not sure which schematic you are using.

Well the schematics are not very beautiful, and the analog part seems still to be missing, but here you can see that, from your description, it is nearly exactly what you made. A Yamaha soundchip (ay38910) and one GAL.
http://www.eightbits.de/schaltplan-sonX-beta-v001.png
the audio part can be guessed from
http://www.eightbits.de/bestueckung.png

and GAL EQUATIONS:
http://forum.tlienhard.com/phpBB3/viewt ... =464#p3525

I hope this helps.

[Andy Rea]

Well from the schematic it seems like he is fully decoding but the absence of A0 in this gal code is interesting (ah i see now from the schematic that A0 is connected to A8 on the ay chip, so the result is the same as my gal code, on my ay chip a8 = +5v and /a9 =0v) , but i'm guessing that it it of little inportance A0, is used to read keyboard, and start NMI, it should always be '1' high when we are trying to use zon-x

Gal16V8
#
Clk A1 A2 A3 IRQ WR A6 A7 A5 GND
/OE NC NC NC NC NC BC1 BDIR Q0 VCC
#
Q0 := /Q0
IF(VCC)
BDIR = /WR * /IRQ * A1 * A2 * A3 * /A5 * A6 * A7 + /WR * /IRQ * A1 * A2 * A3 * /A5 * /A6 * /A7
IF(VCC)
BC1 = /IRQ * A1 * A2 * A3 * /A5 * A6 * A7

it is alomost the same as my own gal code, except i added the read option as well so i can used the 8 bit port at a future date.

Name zonx ;
PartNo 00 ;
Date 12/08/2011 ;
Revision 01 ;
Designer andy rea ;
Company none ;
Assembly None ;
Location ;
Device g20v8a ;

/* *************** INPUT PINS *********************/
PIN 1 = clkin ; /* 3.25 Mhz clokc from ZX81 */
PIN 2 = !rd ; /* active low read from Zx81 */
PIN 3 = !wr ; /* active low write from Zx81 */
PIN 4 = !iorq ; /* active low io-request from zx81*/
PIN 5 = a0 ; /* z80 address lines */
PIN 6 = a1 ; /* */
PIN 7 = a2 ; /* */
PIN 8 = a3 ; /* */
PIN 9 = a5 ; /* */
PIN 10 = a6 ; /* */
PIN 11 = a7 ; /* */
PIN 13 = !oe ; connected to ground
/* *************** OUTPUT PINS *********************/
PIN 22 = ayclk ; /* clock to ay (3.25 div 2) */
PIN 21 = aybdir ; /* bdir for ay chip */
PIN 20 = aybc1 ; /* bc1 for ay chip */
pin 19 = cf ; /* not connected to anything */
pin 18 = of ; /* not connected to anything */
pin 17 = read ; /* not connected to anything */
pin 16 = write ; /* not connected to anything */
pin 15 = select ; /* not connected to anything */

/* ***** LOGIC ******/
ayclk.d = !ayclk ;

cf = a0 & a1 & a2 & a3 & !a5 & a6 & a7 ; /* the absence of A4 makes this decode $df also */
of = a0 & a1 & a2 & a3 & !a5 & !a6 & !a7 ; /* the absence of A4 makes this decode $1f also */

read = iorq & rd & of ; /* conditions to read ay register */
write = iorq & wr & of ; /* conditions to wriet ay register */
select = iorq & wr & cf ; /* conditions to select ay register */

aybc1 = select # read ; /* bc1 true for select or read */
aybdir = write # select ; /* bdir true for select or write */

Andy

Ohhh i just noticed i am using 20V8, a few more inputs than the 16v8...

[Paul]

Well, reading the ports would be essential if the ports should be of any use to me
Else no centronics printing could be done, no SDCard reading, no Vdrive USB...
I hope this can be corrected..

[Paul]

Yesterday I added wires to the power tracks to get more power over them. I also added Tantal capacitors to the ICs. But no difference in the sounds.
Next I will try to add a bus to the Soundcard to put zxpand behind it. It will be an awful lot of wires, but its for testing only.

I forgot, Sascha tested the reading of the ports. No problem as reading is the default in this board whenever we are not writing to it.

[Paul]

My sound card works in conjunction with the ZXPAND. Super Fast loading and great sound.

I had no rest. So I've gone home early and went into the basement.
I tried again, but no change.
Then I watched the bus from ZXPAND again (for the umpteenth time). Everything looked great.
Then I measured again (for the umpteenth time) and A3 had no contact

A3 was certainly the cause. After I resoldered A3 everything works.

Thank you for all your help and patience! And my excuses that I've kept you so busy

[sirmorris]

C O N G R A T U L A T I O N S

[Andy Rea]

Whooey

See told ya it would be something simple

Andy

[Prime]

Whooey

See told ya it would be something simple

Indeed I've lost count of the number of prototypes that I've had not work because I forgot to solder something (usually on the top of the board).

Cheers.

Phill.