Is your Ti 99/4A too fast?

[mnbvcxz]

If you have the 16 bit memory and speed upgrades fitted, are there any programs which will not run?

If you write software, do you make it tolerant of these upgrades?

I am considering installing these upgrades, both have switches to disable them, but I do not want to drill holes in the casing to fit these switches if they are unnecessary.

Thanks.

[+Lee Stewart]

Among a few other things, there are timing loops that rely on memory access speed. Those loops will definitely be negatively affected.

 

...lee

[marc.hull]

If you have the 16 bit memory and speed upgrades fitted, are there any programs which will not run?

If you write software, do you make it tolerant of these upgrades?

I am considering installing these upgrades, both have switches to disable them, but I do not want to drill holes in the casing to fit these switches if they are unnecessary.

Thanks.

 

I have not seen any that would not run including disk managers and Telco. Rs232 and printers (mine anyway) work fine. They obviously run faster which may be undesirable for certain programs.

 

Personally any software I write is geared towards the stock machine but I develop it using fast memory and a fast crystal as it makes the assemble cycle far faster. Only problem I have encountered is with the 9901. Every couple of years it seems to bonk out. I suspect that is due to the fast crystal though and not the 32K16.

 

I would definitely install the switches so you can speed up the development process but test under normal circumstances. Otherwise you may write something you think is perfect and when it gets run on a console without the mod it appears sluggish.

 

By all means a good and useful mod. Well worth the time.

[+Lee Stewart]

I doubt the mod plays well with the nanoPEB/CF7+, which has its own 32KB RAM.

 

...lee

Edited April 30, 2014 by Lee Stewart

[Gary from OPA]

I doubt the mod plays well with the nanoPEB/CF7+, which has its own 32KB RAM.

 

...lee

 

I disabled the 32kb onboard my CF7+ and used the internal 16bit memory in my console with no problems.

 

Among a few other things, there are timing loops that rely on memory access speed. Those loops will definitely be negatively affected.

 

...lee

 

The most common is poorly written programs that access the Speech Synthesizer directly, when running from 16bit there can be problems if right after speaking a word, you try to access something that is not 16bit, as speech unit is still locked onto bus, but you don't know it.

[senior_falcon]

The only one I've seen is the Tennis program. The sprites that make up the players will get out of synch with each other so you have the head and shoulders swinging the tennis racket while displaced to the side are the legs and torso. It's actually rather comical to see.

[Gary from OPA]

The only one I've seen is the Tennis program. The sprites that make up the players will get out of synch with each other so you have the head and shoulders swinging the tennis racket while displaced to the side are the legs and torso. It's actually rather comical to see.

 

Yeah some programs that have timed loops for moving the sprites and detection get messed up, but it is rare as alot of them base their timing on the VDP interrupt signal which stays the same.

 

If you want to see more messed up programs, and even corrupted writes to your floppies, and fucked up serial data in terminal programs, then you need to up the overall speed of the system, replacing the 12mhz crystal on motherboard with faster one,

you can safely bump it up a bit, without melting the silicon, or if you wish to de-solder the big tms9900 and replace it a tms9900-40 then you can easy bump up your overall speed to 4mhz with a new bigger 16mhz crystal and really have a fast ti99 with 16bit memory!

[marc.hull]

I have wondered in the past if those games that have problems with a 14 MHz crystal were using the 9901 as the frame marker instead of the vdp int. Would make sense as programs that use the 9901 would execute identically on pal and NTSC consoles but become goofy when the 9901 clock is out of spec. Thoughts??