Odd 32k Initialization

[RobertLM78]

Howdy gang! After moving a couple months ago, I started to notice some issues with the serial bridge (via TIImageTool), as well as regular PC to TI connections via MFM. Sometimes the connections worked, but most times they don't (interestingly, the first test I did this morning was successful using serial bridge - I didn't try MFM). Somehow I had the idea to check the high memory of the 32k Expansion using the following loop in XB:

 

FOR I = -24575 TO -1 :: CALL PEEK(I,K) :: PRINT I+24575;K :: NEXT I

Now, running that command in MESS gives the expected results, with all the K's being equal to zero. On the real iron though, I get weird results, though typically, K=255 for the first ~64 bytes in memory, then zero for the next ~64 bytes and so on.

 

I should also mention that I can load values into the high memory, and peeking the memory again shows that the values have retained themselves. So I guess the question is, although the memory seems to be working in every other respect, could these odd values in memory be causing confusion if the computer expects the address to be empty (i.e., zero)? Or is there something wrong with my RS232 (a CorComp)?

 

Thanks for reading!!

Edited March 30, 2014 by RobertLM78

[+mizapf]

Hi Robert,

 

what I know about the standard TI 32K is that the even bytes appear as 0xFF while the odd bytes are 0x00. That is, after power-up, memory words show up as FF00 FF00 FF00 etc. This is also emulated in MESS when you turn off the 32K console mod and instead plug in the 32kmem as a peripheral card.

 

There was one case where this behavior made a big difference: The TurboPasc99 compiler and runtime refused to run when memory is initialized as 0000. And I remember that it was the time when I upgraded my console when I gave up on TurboPasc.

 

What 32K mem are you using in real life?

[RobertLM78]

Hi Robert,

 

what I know about the standard TI 32K is that the even bytes appear as 0xFF while the odd bytes are 0x00. That is, after power-up, memory words show up as FF00 FF00 FF00 etc. This is also emulated in MESS when you turn off the 32K console mod and instead plug in the 32kmem as a peripheral card.

Heya Michael! How do I turn off the console mod? I thought I was using the 32k card in MESS . I think I turned off the console mod in MESS, but now I'm getting alternating 73h and 0h.

 

There was one case where this behavior made a big difference: The TurboPasc99 compiler and runtime refused to run when memory is initialized as 0000. And I remember that it was the time when I upgraded my console when I gave up on TurboPasc.

 

What 32K mem are you using in real life?

In RL, I use the TI-made 32k expansion.

 

EDIT: O.K., I think I got proper emulation in MESS of the 32k memory expansion. I now get K=0,255,0,255,0,255,... So that leaves the question, why is my card giving such odd results?

Edited March 30, 2014 by RobertLM78

[RobertLM78]

As an update to this: I have been lead to believe that the real culprit here is the cartridge port, however, I'm not sure if a dirty cartridge port could in fact cause an odd initialization of the 32k expansion, and of course, there's no way of checking the memory without an E/A cart or an XB cart plugged in (at least to my knowledge - Senior_Falcon - any tricks you know?). I suspect the cartridge port because sometimes the computer doesn't start properly when a cartridge is in the port, and if the computer does start, the 'on-beep' sounds weird - kind of a stretched and struggling sound. When I take the cart out of the port, the 'on-beep' is normal sounding.

[+Ksarul]

You might want to make sure that the felt in the cartridge port (assuming you have not removed it yet) is not filled with lots of grease and metal bits. That will cause problems like yours. You might also have a cracked lower cartridge port connector or some fatigued solder joints.

[RobertLM78]

Thanks for the advice Ksarul. It looks like I might have to take the machine apart and inspect that port. Hopefully it's just dirty.

[Gazoo]

Thanks for the advice Ksarul. It looks like I might have to take the machine apart and inspect that port. Hopefully it's just dirty.

 

I've found that it's best to take the plastic cover off the cartridge connector, remove the felt, and discard both.

Pour some alcohol in the cartridge connector and scrub it with a toothbrush - get in there!

 

Gazoo

[RobertLM78]

Thanks for the advice Gazoo and Ksarul. I finally went ahead and did the cleaning today. I removed the plastic and felt and discarded them both. The "on beep" definitely sounds more normal now, but I'm still getting a weird 32k initialization. I'll do more testing today to see how the computer in general performs, including RS232 transfers.