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Powertran Cortex

[rant mode]

Did you guys get the notification from ebay that they're no longer supporting wildcard searches? I've got a search for "tms99*" to find all the TMS99xx series chips that come up. But ebay in their wisdom reckon that isn't giving me the search results I want. Apparently now I have to provide a search term for each individual chip as searching for just "tms99" only returns 3 results versus the 118 results that the wildcard search gave ...

[/rant mode]
 
I didn't even realise you could use wildcards like that.
But, i do know they've "improved" the search a few times in the last year or so.
Searchs i've had setup for years that used to return only exactly what i was looking for, nowadays return auctions with similarly spelt and parts of the actual search terms i've requested.
E.g my search for Microtan (as in Microtan 65) now returns hits for Micron memory all the time.

Jim
 
Floppy drives working.

Floppy drives working.

Finally got the floppy drives working.
I found Daves great utilitys on www.powertrancortex.com which lets you download programs from a PC to the Cortex through the RS232 interface and then lets you create disk images on the Cortex itself.
There are so many combinations of sides, tracks, density etc that initially i couldn't get it working.
But eventually i got the combination right and was able to create the SS SD 80 track boot disc.
And then finally BOOT worked.
I then created a DS DD 80 track disk but while it appeared to download and write ok using Daves utility i get disk controller errors trying to access it.

But then Dave does say DD is tricky to get setup.

Some good news though, it means that the TMS9911 from Littlediode are OK even if the TMS9909 from UTSource aren't.

I also fixed the random beeps, that was down to IC64, a 74LS259. Now replaced for the moment with a modern 74HCT259 as i only seemed to have had the one.

So, thanks again Dave for your utilitys, i'd not realised you'd updated the web site so much since i first saw it.

Jim
 
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Great news Jim!!!!!!!!!!!!!!!!!!!

I'm glad all that stuff I did came to good use. It's nice to share. I only recently revisited my website and found a lot of the links to files broken. Not sure how that happened, it's like the Host deleted everything over a certain size. I have put everything back as it was but if anyone notices a problem let me know and I'll restore it again.

I think you'd be wise to look into getting a couple of 3.5" floppy drives in place of the 5.25" ones. It's been my experience that 3.5" drives are more stable when compared to the 5.25's and this helps with the somewhat unstable Double Density Data Separator circuitry. I recall at one stage I had a pot on the back of one of my computers that I sort of twiddled to find a sweet-spot for DD operation with some really old 80T, DSDD drives. If push comes to shove I can take a look to see what resistor values are in there now. I think I recommend a specific 3.5" model somewhere on the website? They just have to be capable of running at 300 rpm and have drive-select signals (and you need to cover up the HD hole on the diskettes).

Anyway, awesome news!

Dave.
 
tms9995 said:
I only recently revisited my website and found a lot of the links to files broken. Not sure how that happened, it's like the Host deleted everything over a certain size. I have put everything back as it was but if anyone notices a problem let me know and I'll restore it again.
Click to expand...

Looked into this. Turns out the 'free' web host I have been using has a policy whereby, at their discretion, they might delete files over 5MB. I wish I'd known about this as I would never have used them. I just wanted to get everything up on a website for everyone to share. Once it was up there and working, I didn't revisit it as I had no need to change anything.

Anyway, I have now moved to a paid host... I apologize for the broken links in the past year or so and hope that it is once again complete.

Dave.
 
tms9995 said:
I think you'd be wise to look into getting a couple of 3.5" floppy drives in place of the 5.25" ones. It's been my experience that 3.5" drives are more stable when compared to the 5.25's and this helps with the somewhat unstable Double Density Data Separator circuitry. I recall at one stage I had a pot on the back of one of my computers that I sort of twiddled to find a sweet-spot for DD operation with some really old 80T, DSDD drives. If push comes to shove I can take a look to see what resistor values are in there now. I think I recommend a specific 3.5" model somewhere on the website? They just have to be capable of running at 300 rpm and have drive-select signals (and you need to cover up the HD hole on the diskettes).
Dave.
Click to expand...

Ah, but 3.5" drives aren't correct for the Cortex are they.
I know, neither is the PC power supply it's currently running on but i'll replace it with a switcher at some point.
Spent a bit more time recently trying to get better quality video out of it, the TV out into a PC TV card is very poor, with certain colour combinations it doesn't manage to stay synced art all.
I've checked over the video signal into the modulator and it seems correct, i've checked the sync levels as mentioned in the newsletters but that all seems correct as well.
I changed the modulator in the end but no difference.
I think the next thing will be a RGB or component out interface.

Jim
 
Jim Hearne said:
Ah, but 3.5" drives aren't correct for the Cortex are they.
Spent a bit more time recently trying to get better quality video out of it, the TV out into a PC TV card is very poor, with certain colour combinations it doesn't manage to stay synced art all.
I've checked over the video signal into the modulator and it seems correct, i've checked the sync levels as mentioned in the newsletters but that all seems correct as well.
I changed the modulator in the end but no difference.
I think the next thing will be a RGB or component out interface.

Jim
Click to expand...

Your PC TV card no doubt supports composite NTSC. So you could replace the video chip with a 9918 which gives a direct composite output - it just needs a pull-down resistor on the video output. Pin compatible apart from (from memory) 3 pins, which you would have to bend out of the socket. Would probably need a different crystal as well, thinking about it.

There's also the new F18A video chip replacement board (http://codehackcreate.com/) which gives you a VGA output you can connect to another monitor.

Neither of these suggestions are correct for the Cortex though. ;-)

Stuart.
 
Stuart said:
There's also the new F18A video chip replacement board (http://codehackcreate.com/) which gives you a VGA output you can connect to another monitor.

Stuart.
Click to expand...

Nice find Stuart! I might be very tempted to get one of these (especially since I don't own a 'real Cortex' anyway :( ). Being able to use a regular monitor would be a bonus, and it adds the V9938 80 column mode which I use all the time.

Dave.
 
I've got a 9904 also made in Malaysia with identical markings apart from some of the numbers being different, so I'd cautiously suggest that these are good. Maybe e-mail the seller first and just say that you're aware there are some fake TI chips round at the moment and will he give a full refund if there is a problem.

Stuart.

mnbvcxz said:
I have seen on ebay tim9904 described as 8 to 3 line encoder, having read that components from utsource are sometimes fake, do you think this is worth a try?

http://www.ebay.co.uk/itm/120920839918?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

Thanks.
Click to expand...
 
Christmas greeting to everyone. I'm lucky enough to have nearly 2 weeks off work so there's a real risk I might get round to buying sockets for my bare Cortex board ...
 
Go for it, Stuart! I may have to start on mine as well. . .assuming my five and seven year old boys let me have some "me" time. . .not to mention the wife! ;)
 
The deed is done and most of the PCB hardware is now ordered. I'll try to order the ICs on E-bay over the next couple of days. Need to hide the credit card bill from the wife next month ... ;-)

I'm planning on the following changes:

(1) ZIF sockets for the three EPROMs. EDIT - scrub that idea. It looks as if the holes in the PCB for the IC pins are too small for the pins of a normal ZIF socket.

(2) I'm not going to build the keyboard. I could probably get suitable key switches, but the hardware for the space bar may be a problem, and getting the exact set of labelled key tops is probably not reasonably possible. Instead I plan to control the Cortex from the PC through the RS-232 interface. May need to modify the EPROM code to change some Cortex keyboard scan codes to suitable PC Ctrl key codes.

(3) I'm not going to fit the analogue PAL video hardware, instead I'm going to fit a TMS9918 which gives a direct composite output (just needs a pull down resistor) which works with my PC TV tuner card. I'll need to bend 3(?) IC pins out of the socket so I don't have to modify the PCB.

(4) I'm going to power the board from a PC power supply unit, and have ordered an ATX extension lead that I can modify for the purpose.

Jim: I haven't been able to order the following capacitors. Would you happen to have one of each kicking around? They're for the tape interface, which I don't plan to use other than confirming that it's working. C22 (330n), C24 (5n6), C23 (2n2).
 
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A good idea ... but I haven't got the room in my little computer corner for another monitor, and I don't really want to have to shuffle monitor cables around whenever I want to use it.
 
Stuart said:
(2) I'm not going to build the keyboard. I could probably get suitable key switches, but the hardware for the space bar may be a problem, and getting the exact set of labelled key tops is probably not reasonably possible. Instead I plan to control the Cortex from the PC through the RS-232 interface. May need to modify the EPROM code to change some Cortex keyboard scan codes to suitable PC Ctrl key codes.


Jim: I haven't been able to order the following capacitors. Would you happen to have one of each kicking around? They're for the tape interface, which I don't plan to use other than confirming that it's working. C22 (330n), C24 (5n6), C23 (2n2).
Click to expand...

Hi Stuart,

Have you considered using a microcontroller to interface to a PS/2 PC keyboard? The output from the micro can be made to match the Cortex keyboard controller and you get the 'key-down' functionality for games etc. which is not easy to do using the RS232 port. I did it once just to prove the concept using an Atmel chip (they provide an Application Note that gives the circuitry and software as a foundation, so very easy to do: http://www.atmel.com/Images/doc1235.pdf).

This would keep the RS232 port free to use to save/load programs to/from a PC using the PC Comms Util ;)

Dave.
 
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tms9995 said:
Hi Stuart,

Have you considered using a microcontroller to interface to a PS/2 PC keyboard? The output from the micro can be made to match the Cortex keyboard controller and you get the 'key-down' functionality for games etc. which is not easy to do using the RS232 port. I did it once just to prove the concept using an Atmel chip (they provide an Application Note that gives the circuitry and software as a foundation, so very easy to do: http://www.atmel.com/Images/doc1235.pdf).

This would keep the RS232 port free to use to save/load programs to/from a PC using the PC Comms Util ;)

Dave.
Click to expand...

You're taking me out of my comfort zone there Dave, suggesting using something as modern as a microcontroller. ;-) One reason I do have for using the PC is that I have a little program to send text a character at a time from a text file down the RS-232, so I can 'save' by simply listing a program over the RS-232 then copying it into a text file, and 'load' by using the program to send it back again. You're right about the 'key down' functionality for games though.

Will hopefully try getting the Cortex running tomorrow if the last of the IC sockets arrive.

Stuart.
 
Stuart said:
You're taking me out of my comfort zone there Dave, suggesting using something as modern as a microcontroller. ;-) One reason I do have for using the PC is that I have a little program to send text a character at a time from a text file down the RS-232, so I can 'save' by simply listing a program over the RS-232 then copying it into a text file, and 'load' by using the program to send it back again. You're right about the 'key down' functionality for games though.

Will hopefully try getting the Cortex running tomorrow if the last of the IC sockets arrive.

Stuart.
Click to expand...

You're probably right. They can be a bit intimidating. So, to make it simpler, why don't you use the TMS99110 system you designed to act as a PS/2 keyboard interface? That would be cool!

I hear what you're saying about listing the file to and from the PC, but it's slow and can be clunky if the line expands to be too long. I think you should at least give the Comms Util a crack. It will take care of your machine code as well, since you can use the MONitor commands to save/load. It's not far off a Cortex with disks as far as performance is concerned.

Anyway, good luck with the Cortex build!

Dave.
 
Stuart said:
I've got a 9904 also made in Malaysia with identical markings apart from some of the numbers being different, so I'd cautiously suggest that these are good. Maybe e-mail the seller first and just say that you're aware there are some fake TI chips round at the moment and will he give a full refund if there is a problem.

Stuart.
Click to expand...

Probably too late now (I didn't realise there had been any more messages here, I must have missed an emailed notification) but that is the company that sold the fake TMS9909 chips.

Jim
 
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