464 Resurrection - with only mainboard!

[TotO]

struggling to build up the ps2 adapter... dunno why ...but its stressing me out hard

Why directly hacking the PCB circuits pins instead of using the keyboard connector to build an adapter?

[WacKEDmaN]

struggling to build up the ps2 adapter... dunno why ...but its stressing me out hard

Why directly hacking the PCB circuits pins instead of using the keyboard connector to build an adapter?

good question!.. i was originally using the keyboard connector with arduino mega..but my code sucks and it was too slow..i was getting multiple keys or keys in different rows at times
so im doing Geralds PS2 adapter (just without a premade board)... the code is completely setup to use pins from the chips directly and not the keyboard connector pins. i guess i could use the keyboard connector pins that connect to the AY-3.. but the code bypasses IC101(LS145 decoder) and also uses IOWR/CS and A0/A1 from the PPI to know when the keyboard is being read

on third thought...
im going to build it up on a breadboard first... might save me some stress to get the board right!..and will allow me to test the pin outs in the schematic are correct (there seems to be some disagreement about that)

this is the schematic im working from...
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[TotO]

Yes, it mainly use PC0-PC3 (A, B, C, D) form the PPI and X0-X7 from the AY.
And it require a "chip select" signal when the PPI PortC is written.

/CS = (/IOWR OR A11) with A8=1 and A9=0

[WacKEDmaN]

so i think ive got the PS2 adapter hooked up properly.. the Num lock led is lit...

but.. most the keys do nothing!.. some of the function keys pump out a bunch of characters... up and right arrow aswell.. and a few of the keys on the num keys..
eg if i hit right arrow key.. ill get 2\/MNBC  hit it again and ill get 2\/mnbc (switches between shifted and not shifted)

...my keyboard is US... i guess its throwing out different key codes..which are not programmed into the adapter code

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.....i just spotted something i missed.... the pull up resistors for the ps2 clk and data!..and smoothing caps...SMH
EDIT: so ive attached them ...and now its worse!.. num led doesnt turn off.. and its ALWAYS sending keys to the CPC!.. just constant stream of characters!

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[eto]

As far as I know, PS/2 keyboards also just have a matrix and send a key code based on that matrix, not caring about what version it is. International versions just have different keycaps and send the same key code, if the position of the key on the keyboard is the same.

If you want to map a US layout to the CPC layout, you have to translate this in your code.

[WacKEDmaN]

yeah.. i thought as much...

this "solution" is really stressing me out.. i dont like it!
im considering hooking the arduino mega back to the keyboard connector and learning how to code the interrupts and port bit flipping (i was using digitalRead() and digitalWrite() but they seem too slow)

[WacKEDmaN]

..resoldered everything.. and now its working perfect...
Stoked!.. now to wait on some cash to get a USIFAC II so i can load some stuff...

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[WacKEDmaN]

so now ive got keyboard working.. its on to the next project...(while i wait for cash and USIFAC II)
i need a way of loading tapes/CDTs without the tape deck...

looking at the schematic, i see that the signal from the tape head is going through 2 op amps and a tranny..im thinking about using an ESP32s audio out capabilities..i guess i will need to make up an amplifier circuit to boost the signal enough for the cpc to see...

....i have some questions tho... 
cant this be done purely digitally?.. i mean just feed a digital signal straight into the connector on the 464 board (near the power switch)
does anyone have a scope handy, to show me what the signal going out of the tape deck into the main board looks like please...(scope at the data out/in pins on the mainboard)

[Bryce]

That's exactly what those two "op-amps" are doing. Taking the analogue signals from the tape/CDT and converting them into a digital signal. Of course loading can be done fully digitally, it's called loading from a disk, but if you want to read CDT's then you are starting with an analogue signal so the conversion has to happen somewhere.

Bryce.

[eto]

Check out this video: 
https://www.youtube.com/watch?v=-cacZqQf4Go

It shows, how to add an audio-in to the 464, that works with different sources like TZXduino or an Ipad. 

One thing I was also wondering while watching this and its follow-up video is, if it's possible to feed the TZXduino data directly into the PPI. Noel is doing that with the BUSY pin of the printer port to create a speed loader. I guess that should also work with the normal data-in port, if you disconnect the audio circuit:
https://www.youtube.com/watch?v=MAIsOIwgJWA&t=1348s

[WacKEDmaN]

thanks Bryce...

and eto.. the problem is i dont have a tapedeck/tape circuitry.. the usual method sends the signal through the op-amps before sending it to the mainboard...
but yes! i forgot all about that Printer port method... 
i should be able to do the same sort of thing with an ESP32 instead of the TZXduino (i can probably use code from it tho!)

i could even connect the "play on input" pin to trigger the esp32 to start sending the cdt...(and then a web interface (over wifi) to select/upload cdts to the esp32s flash)

this project isnt really a priority, just something to work on while i wait for USIFAC II...

also just got a hold of a BASIC 1.1 ROM (Patched to show 64K instead of 128K)
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[WacKEDmaN]

built up a tzxduino on mega2560 board..
hooked the output pin from the mega to the data in port on the cpc board..
set the tzxduino running and was greeted with it detecting the first block..runs great..i need to speed it up, im using default baud and its quite slow!



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and heres a vid of it loading first time.. and the current setup!

[WacKEDmaN]

seems im still having an issue with IC115 (74LS244)  
ive resoldered the socket (multiple times!)..but still having random crashes or reboots seemingly related to that IC.. eg if its pushed in too far it boots with gray screen and video corruption, ..or if i tap the IC or board it will sometimes reboot..(remember a brand new LS244 also fails in this socket!) 

ive even had it reboot just from looking at it!!..i mean it will sit there fine for like an hour or so, i turn my head to look at the screen and boom reboot!! (happened a few times now!)..i know just coincidence ...but damn!

looks like i have to replace the socket, and if that doesnt work, solder the chip in directly... i dont see why the socket would be causing issues like this tho..

[Audronic]

If you have to replace the socket perhaps try Turned sockets as it looks like you are using Double Wipe

Good luck

Ray

[WacKEDmaN]

unfortunately i dont have any machined sockets handy..i do have a new dual wipe to go in tho..

..this board is so much easier to desolder and clean up than the old original board...

[WacKEDmaN]

so soldered in the new socket... and the new LS244 works fine...but STILL getting reboots if i tap/move the board...
tryed reflowing the other sockets around the ls244...including memory.. it doesnt seem as bad..but its still an issue...

seems it cured most of the random reboots... like its been running Ikari Warriors for the last 12hrs... only seems to reboot if i bump or tap the board now...

[WacKEDmaN]

oh nice.. i fired up javacpc to search for some games...
i found that you can convert disks to tape!...
so looks like im all set!..
ill still get a USIFAC II coz tape loading is slow..and ive gotta get up to change cdt on the txzduino

also...anyone know why Hunckback II doesnt like 664/6128 ? it just reboots half way through loading (does weird stuff on emulator too!) ..wont work the the 6128 rom installed...works fine with the 464 rom (that also includes the disk version converted to cdt which is very strange!)...its the only game ive found that has these sorts of issues..

[eto]

It probably uses some firmware addresses that have changed for the 664/6128.

There is at least one cracked version that has been patched to work on all machines. You can find it on cpc-power.com.

[WacKEDmaN]

now it runs crysis! 
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made up a crappy screen in javacpc.. saved to disk..transfered to cdt.. then loaded up on the real machine! 

[WacKEDmaN]

now with loading sound!
i think i found why the loading sound is played through the speaker... its coming back from the AY-3... the sound out (of the mainboard) provides the loading sound... i tested this by only connecting the sound out to the amplifier...

[WacKEDmaN]

usifac ii seems to be working now..(needs ~6.5v with this board)
no tech support needed.. but thought id share my latest DIY addition..

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[CaptainRon]

@WacKEDmaN, Awesome write up. I'm glad you were finally able to bring it to life! 

I'm interested in the ps/2 keyboard mod you did. Can you link the the build you are using?

I just ordered one of the "Bob's bits" 6128 boards but don't have a case, keyboard, or drive for it so will be in a similar situation as you were. I am trying to come up with a solution before the new board arrives from UK.

These old CPC's are ultra rare in USA so there is no chance of getting any spares here. I plan on 3d printing a case with enlarged floppy bay to fit a 3.5 inch drive and retrofitting a PS/2 keyboard somehow.   

[WacKEDmaN]

@WacKEDmaN, Awesome write up. I'm glad you were finally able to bring it to life!

I'm interested in the ps/2 keyboard mod you did. Can you link the the build you are using?

I just ordered one of the "Bob's bits" 6128 boards but don't have a case, keyboard, or drive for it so will be in a similar situation as you were. I am trying to come up with a solution before the new board arrives from UK.

These old CPC's are ultra rare in USA so there is no chance of getting any spares here. I plan on 3d printing a case with enlarged floppy bay to fit a 3.5 inch drive and retrofitting a PS/2 keyboard somehow. 

Thanks!

the ps2 adapter is here...
https://www.cpcwiki.eu/forum/amstrad-cpc-hardware/is-there-any-recent-project-to-connect-a-pc-(ps2)-keyboard-to-the-cpc/175/

for the 6128 board, you'll need a 40010 Gate Array...which is hard to get, you might want to use the CPLD replacement..
https://github.com/codedchip/AMSGateArray

for disk drive, use get DDI-5 or USIFAC, or M4board, etc

[WacKEDmaN]

today i hooked up the esp8266 to the gbs-8200
..the gbs worked ok out of the box, but had some vertical lines, and the characters looked a little blury...
so after hooking up gbs-c (and some playing with the settings) ive now got a perfect picture...and even got scanlines! (at various intensities)
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[WacKEDmaN]

thought i posted this yesterday...but must of forgot to hit the post button! 

so i need a case for my CPC board and bits... was thinking about getting a clear case made up for it (but that will be costly)
...i found an old box my grandfather made for his lawn bowls made from beautiful Cedar wood... 
im thinking about making some sort of "laptop" with it (it'll be tooo big for ya lap tho!)

what do yas reckon?! worthy?! (this is just a mock up to see that everything fit!..even fits the joystick and still allows it to be closed)

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