Timex 2048 only 16k

[landex]

Hi
I'm new here.
I bought a Timex 2048 from Portugal, and I realized that something was wrong. I type:
PRINT PEEK 23733

Output was: 127.
I load jetpac and work fine. Then I try to load a 48k games and it doesn't work.
Can it be a memory chip?

[1024MAK]

Hello,

What does PRINT PEEK 23732 + PEEK 23733 * 256 return?

Here’s a 48K ZX Spectrum quick ‘n simple RAM test. I’ve not tried it on a Timex 2048.

Code: Select all

1 CLEAR 24999
2 FOR a=25000 TO 65535 STEP 250
3 PRINT AT 0,0;a: POKE a,0: LET d=PEEK a: IF d<>0 THEN GO SUB 8
4 POKE a,255: LET d=PEEK a: IF d<>255 THEN GO SUB 8
5 NEXT a
6 PRINT “done”: STOP
8 PRINT “error at “;a;” “;d
9 RETURN

RAM test, test one address only looking for a bit error. Again written for a ZX Spectrum. Not tested on a Timex 2048.
Use an address reported as faulty from the above program.

Code: Select all

1 CLEAR 25999
2 PRINT “Enter address to test”
3 INPUT a
4 PRINT “Address ”;a
5 FOR c=1 TO 4
6 READ t
7 POKE a,t: LET d=PEEK a
8 PRINT “Value written ”;t;“ value read ”;d
9 NEXT c
10 DATA 0,85,170,255

Mark

[landex]

PRINT PEEK 23732 + PEEK 23733 * 256

Output:
32767

[landex]

Hello,

What does PRINT PEEK 23732 + PEEK 23733 * 256 return?

Here’s a 48K ZX Spectrum quick ‘n simple RAM test. I’ve not tried it on a Timex 2048.

Code: Select all

1 CLEAR 24999
2 FOR a=25000 TO 65535 STEP 250
3 PRINT AT 0,0;a: POKE a,0: LET d=PEEK a: IF d<>0 THEN GO SUB 8
4 POKE a,255: LET d=PEEK a: IF d<>255 THEN GO SUB 8
5 NEXT a
6 PRINT “done”: STOP
8 PRINT “error at “;a;” “;d
9 RETURN

It gets errors after address 33000 .

[sP1d3r]

Can it be a memory chip?

A Timex TC2048 has two different types of memory chip, two 4416 and two 4164 chips, IIRC.
The thing to do would be to desolder and test the chips with a DRAM tester, this would eliminate the memory chips as the source of the problem.

[landex]

Can it be a memory chip?

A Timex TC2048 has two different types of memory chip, two 4416 and two 4164 chips, IIRC.
The thing to do would be to desolder and test the chips with a DRAM tester, this would eliminate the memory chips as the source of the problem.

Sp1d3r, it's very interesting what you said. My has four 4164 chips. Some one made a mistake. Só don't you think?

[landex]

can I use an mk4116n-2 to substitute the 4416 chips?

[sP1d3r]

can I use an mk4116n-2 to substitute the 4416 chips?

4116 DRAM chips are 1-bit but 4416 chips are 4-bit, so no because they're not compatible.

Can you post a picture of the whole motherboard?

[sP1d3r]

Here's a pic of my TC2048, it has 2 4416 and 2 41464 chips but this is possibly a different version because it looks like yours has a different mix of DRAM chips.

[landex]

My has more 2x4164 chips, Here