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mizapf

Member Since 31 Jan 2013
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#4263647 TI-99 Photos Thread! Post your systems here!

Posted by mizapf on Tue Apr 23, 2019 5:38 PM

I just sifted through my old floppy disks, and this caught my attention. My first floppy drive was single-sided, hence the cutouts. No, this is not what I mean. This is a SSDD disk - look at the label on the upper left corner. I doubted that they actually existed.

 

The problem is that when you have a sector dump disk image of 180 KiB, this should be considered a DSSD disk. For the sector dumps, MAME actually peeks into sector 0 to make sure, but if that disk is not formatted, this may be a problem, because a SSDD disk with 18 sectors/track, 40 tracks, and 1 side has exactly 720 sectors like a DSSD disk with 9 sectors/track, 40 tracks, and 2 sides.

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#4263641 TIPI - Geneve 9640 to Raspberry PI interface development

Posted by mizapf on Tue Apr 23, 2019 5:28 PM

I just tried it on my DDCC-1 on the Geneve. A CALL DIR(1) succeeds with single density and rompage speed 5, but not with double density. However, the DIR subprogram even locks up with rompage at speed 1 with DD.

 

I should have a TI disk controller somewhere in my cardboard boxes to check this. It may be easier this way because we have schematics for the TI FDC, and its operation is well understood. (Does not help with DD, of course.)

 

Real hardware sucks.  :)  I'd like to simply glue in some log commands, as I do when debugging in MAME.




#4263532 TIPI - Geneve 9640 to Raspberry PI interface development

Posted by mizapf on Tue Apr 23, 2019 2:32 PM

I believe many people here are not aware of that. In fact, I planned the Ninerpedia to be a storage for all our TI knowledge, just like Wikipedia does for everything else.




#4263449 TIPI - Geneve 9640 to Raspberry PI interface development

Posted by mizapf on Tue Apr 23, 2019 12:02 PM

 

Michael, not sure who manages this website, but I saw a mistake under the GPL Interpreter section.

 

It is running on my webserver, but it is nonetheless a Wiki - typically meant to be a collaborative project. I can correct the information, but in general, if you have good reasons to change something, you need not wait for anyone; just boldly log in and go where no one has gone before. :)

 

(In fact, the digits were swapped, should have read >35)




#4263374 Ninerpedia upgraded

Posted by mizapf on Tue Apr 23, 2019 9:43 AM

Hi all,

 

just a short announcement: Ninerpedia has been updated to the latest MediaWiki version, and user registration is possible again. Registration was turned off for some years now ... nobody really noticed. I have to confirm all account creation requests; I still remember when we forgot to do that and the whole site was turned into a pharma stuff marketplace in a single night (hundreds of pages and hundreds of pseudo accounts).

 

I am in the process of moving MAME- and TIImageTool-specific information from Ninerpedia to my own website (www.mizapf.de) so it will be focused more on real TI family stuff and less on my works. Of course, I'll keep summaries and links on Ninerpedia.

 

I noticed I did not yet set up a favicon. This is my suggestion (until someone else comes up with a better one).

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#4263327 FDC on TI-99/4a

Posted by mizapf on Tue Apr 23, 2019 8:16 AM

The middle pin of the resistor leads to the WPW pin (33) of the WD2793.

 

WRITE PRECOMP WIDTH: An external potentiometer tied to this input controls the amount of delay in Write precompensation mode.

 

(from WD279X-02 Floppy Disk Formatter/Controller Family)

 

WRITE PRECOMPENSATION

When operating in Double Density mode (/DDEN=0), the WD279X has the capability of providing a user-defined precompensation value for Write Data. An external potentiometer (10K) tied to the WPW signal (pin 33) allows a setting of 100 to 300 ns from nominal.

Setting the Write precomp value is accomplished by forcing the /TEST line (pin 22) to a logic 0. A stream of pulses can then be seen on the Write Data (pin 31) line. Adjust the WPW potentiometer for the desired pulse width. This adjustment may be performed in-circuit since Write Gate (pin 30) is inactive while /TEST=0.

 

Precompensation is particularly needed for hard disks, but can be used for floppy disks, too. The closer you get to the spindle, the tighter packed the sectors are. This is because we have the same number of sectors in inner and outer tracks. For a safe recording, this difference may need to be compensated.

 

Edit: If you have GIMP, open the attached file (unpacked) and change the visibility/transparency of the layers to check.

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#4262945 TIPI - Geneve 9640 to Raspberry PI interface development

Posted by mizapf on Mon Apr 22, 2019 1:21 PM

Concerning Geneve information, I hope everyone is aware about our texts on Ninerpedia: https://www.ninerped...Category:Geneve

 

(I mean, it's the reason why we're writing them.)




#4262819 Retailers list (1983)

Posted by mizapf on Mon Apr 22, 2019 9:56 AM

This is what I found in my cardboard box; a list of retailers for TI-99/4A and its equipment, originally from TI Germany. I seem to remember I actually asked for that list back in those days.

 

(The addresses are certainly outdated, the ZIP codes are still the old 4-digit ones, and dealers may have long closed their shop and left the market.)

 

I was living in the Frankfurt area, so I had some choices indeed. Maybe some of the other German users here remember their favorite TI retailer.

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#4262707 FDC on TI-99/4a

Posted by mizapf on Mon Apr 22, 2019 6:22 AM

This might help.

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#4262458 FDC on TI-99/4a

Posted by mizapf on Sun Apr 21, 2019 5:11 PM

You mean this card? I don't see the 74LS11; but it is on the MG boards (with the 1773).

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#4262271 Caveman by Sam Moore Jr. - program I found

Posted by mizapf on Sun Apr 21, 2019 10:47 AM

As I just read, you don't have a good way to bring stuff to your PC. Maybe via serial connection and TELCO?

 

Or you can disassemble the file on the TI using the DISkASSEMBLER.




#4262249 Caveman by Sam Moore Jr. - program I found

Posted by mizapf on Sun Apr 21, 2019 10:08 AM

No obfuscation. The CONTROL CHARACTER REMOVED message is shown whenever you tried to load a DIS/FIX 80 object code that was assembled with the C option (compression). In that case, the bytes were included between the tags (B) in binary, instead of being shown in ASCII. For example, when you have the word CAVE, probably with a leading length byte (04), in compressed mode you get "B . C B A V B E   B" (the B are tags; remove them to read CAVE), and the 04 byte before C would be dropped by the loader of the Editor with the above message. In normal mode, it would be "B 04 43 B 41 56 B 45 32".




#4262245 TMS9918A color splash

Posted by mizapf on Sun Apr 21, 2019 10:02 AM

The effect you're seeing is definitely caused by the NTSC signal and the general quality level of the composite signal from the TI's video port. I first noticed it in Parsec, where the little landscapes seemed to be rainbow colored, but in fact, weren't!

 

So that's why I actually never really had this impression, because I had a PAL system? My memories on that topic are fading, since I was using a monitor with my Geneve from the early 90es, so I cannot tell for sure anymore.




#4261907 "Programme fuer den TI-99/4A und TI-99/4"

Posted by mizapf on Sat Apr 20, 2019 5:33 PM

Line 180 seems to be clipped.

 

Here is SPACEKRIEG and RAINGAME. I found them on my disks.

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#4261349 TIPI / RPI / File Project Repository

Posted by mizapf on Fri Apr 19, 2019 4:33 PM

Presenting a password in the URL is considered deprecated: https://tools.ietf.org/html/rfc3986(section 3.2.1).